Ebike Battery Charge Safety: Use A Cutoff Timer

Lets easily add a layer of extra protection to help safeguard your home and loved ones from a battery fire.

We’ve all seen the news reports. When compared to the number of ebikes out in the world, battery fires are extremely (EXTREMELY) rare. But when they do occur they can be catastrophic to life and property.

As a daily commuter who also uses an ebike for an auto replacement, I have been charging daily for years. In fact, since I charge at home and at work, I am generally charging twice daily. So I do a lot of charging, which increases the possibility of a failure, even if it is a small one.

Lets skip to the good part first:
Here is the light-duty timer I use. It costs a whole US$9.99 on Amazon. I have several scattered around at my home, my office and in a couple of garages.

With that out of the way, I’ll spend the rest of my time telling you how to go about using it.

What Kind Of Failure?

I have had chargers fail to stop at the target voltage on three separate occasions: They kept on charging. In one case I was using a premium charger with an 80%-charge setting, that was supposed to stop at 55.4v on my 14S/52v pack. A 52v pack is really fully charged at 58.8v. I walked into my garage and saw the charger with its fan merrily humming along; its little red light telling me it was feeding current into my battery… and it was now at 59.5v. Luckily for me it wasn’t enough to cause the battery to combust, which it could have if I hadn’t walked in and reacted appropriately

The second time it happened was almost exactly the same story. Diagnosis worked through with the charger manufacturer determined an internal component failure. They were prompt with warranty replacements, but who is going to warranty my garage?

What About The BMS?

All drama aside, the BMS likely stopped the battery from accepting the current from the charger at 59.5v. This second layer of safety prevented disaster.

Whats a BMS? There is a layer of protection inside the battery. Ebike batteries typically have a Battery Management System inside that is supposed to stop accepting current if an overcharge is in progress. But if you read the headlines, you already know those can fail too.

As part of my solution to this problem, I started using chargers made for outdoor commercial and municipal use. These units have Mean Time Between Failure ratings in the hundreds of thousands of hours. They are built to work trouble-free for decades.

That is a whole different story explored here: An Ultra-Reliable Ebike Battery Charger.

Add Another Layer To The Onion

We’re going to address the failure-to-stop risk specifically: Plug a countdown timer into the wall, plug the battery charger into it, and set the timer to physically cut the AC power clean off before the battery even has the chance to reach a 100% state of charge, let alone an overcharge. If everything works correctly, this adds significant safety to routine charging.

Whats a Countdown Timer?

Think of a kitchen timer. You want something to cook for 10 minutes, so you set your timer to ’10’ and when 10 minutes expires, you hear the timer going off with a bell. If you have an oven with a cooking timer, it will also shut the oven off.

So What?

Thats what we’ve got here: An oven timer that plugs into the wall, and instead of going ‘Ding’, cuts the power from the wall socket to the charger when time runs out.

What that will do is stop a charger from even enjoying the possibility of failing and overcharging your battery. So we will be gaining two things: First, we’ll be making it more difficult for the charge process to induce a battery to combust. Second, we will be creating a way to charge the battery to a less-than-100% level, which will lengthen its lifespan.

Extending Battery Life

This second benefit is optional, but makes sense to take advantage of if you can. If this is a new topic for you, here is a good explanation of the plusses and minuses of the practice. I have cue’d it up a couple minutes in to skip the technical portion of the explanation.

How Do We Set The Timer?

You may have to go on a short fact-finding mission. You need to know how much voltage your charger puts into your battery in a given time period. You need to either have a charger that displays the current voltage level, or an ebike display on your handlebars that shows current battery voltage (i.e. the display shows something like “46.2” volts instead of showing five bars in a pictograph, which is functionally almost useless, but not uncommon). If you don’t have a voltage display, you will want to fudge one.

Two DIY ways to do this

  1. Use a Multimeter/Voltmeter and take a reading off of your battery leads
  2. Use A Watt/Voltage Meter and plug it inline to your charge plug or cord

I describe the Watt/Voltage Meter in a fair bit of detail in the ultra-reliable ebike battery charger article, so I will, for now, just link you to it and let you take it from there. You can use that information, along with the separate instructions on how to make dependable crimp connections, to put together an inline meter fairly simply. Additionally, you may be able to come across a meter that just plugs straight into your battery.

When we get into the description of doing a robust DIY timer, one of the optional ways to do it will let you directly attach an inline meter.

We’ll discuss an inline meter as seen above, when we describe a custom timer build in a separate article.

You could also use a multimeter, or voltmeter. Those are pretty simple devices you can get for cheap online, or in your local hardware store. You don’t have to spend a lot of money to get one much more accurate than the typically marginal accuracy of ebike displays and watt meters.

Here is a cheap multimeter (US$9.99 at time of publication) that will do the job. I am linking it here chiefly because it has an instruction manual written in understandable English.

For about US$35, you can get hold of a much higher quality product. This unit has a neat feature where the leads you need to plug into for a given job are lit up with little LED guide lights so you can’t screw that part up.

Since I do a fair bit of hobby work around electrical things, I use this slightly fancier model, that runs about US$60. Its a little more accurate, and has a couple of added bells and whistles. Using it I found my voltage display on my Bullitt hill climber was consistently 0.5v lower than the actual battery voltage.

Find Volts-Added-Per-Hour

Now that we have a method of determining battery voltage, lets figure out how much our charger adds in an hour.

I plugged my multimeter’s leads into my battery charge plug. I get a reading of 55.8v. Thats my starting point. I plug in the charger and set an alarm to come back in one hour. My alarm goes off and I hustle back to the bike to take another voltage reading.

57.2-55.8 = 1.4. My charger puts in an additional 1.4 volts into the battery per hour. It is not such a bad idea to run the battery back down and test it again. Go for a third time on general principles. See if you come up with the same number or maybe you want to average three slightly different numbers.

A Worthwhile Detail To Note:
Ebike battery chargers use a method commonly referred to as “smart charging”. Technically speaking, this is what is known as “CC+CV Modes”, where the Constant Current mode pumps power into the battery at the charger’s full current level (usually something like 2 amps). But when the charge starts approaching the voltage limit the charger is set to reach, it switches to Constant Voltage, which slowly ramps down the current being fed into a battery until it gently stops at the final target voltage.

So, bearing in mind the above, we don’t want to be measuring the rate of volts-added-per-hour when we are up near the top of the battery’s capacity, because we will be measuring when the charger is in a ‘slowing-down’ mode.

Now What?

Well, in the above example, if my battery is at 55.8v, and I want to charge it to 100%, I now have an idea how long it should take to fill it up. My 52v battery is fully charged at 58.8v. So 58.8-55.8 = 3. I need three volts. My charger charges at 1.4v per hour … and I know CV mode will slow the charge rate down near the top.

I could be conservative and just set it for two hours, knowing 2.8v is close enough to 3v, and its safer to come up to a bit less than 100%. Or if I need that 100%, I can set it to 3 hours. That is too much time, but not by much thanks to the CV mode slowdown at the end.

In practice, this is a lot more thought than you will need to put into the process on a routine basis. What you’ll be doing is ballparking what you set the timer to, and even if you go over or under by a bit, if you do your part on the math it will not be enough variance to matter if Something Bad happens.

And if you use the timing method to cut power off at a lesser charge state of, say, 80%… you can routinely be off a bit and instead of risking a problem, you’ll end up with maybe an 83% charge. Or 78%. Not enough to matter on most rides.

Myself personally this is exactly how I ballpark my charges with my timer: I don’t worry about getting anything exact and I shoot for 80%-ish.

We Are Ready To Use A Timer

So we’ve done all of our homework. Its time to plug in a timer. What timer should we use? I personally prefer mechanical timers. The old-school spring-wound kind that are immune to weirdness like power interruptions. The kind that are not programmable and are thus not subject to programming mistakes. The kind that need a positive action to set, and are not so susceptible to a little oops like pushing the 4 hour button instead of the 2-hour button. Also a mechanical timer is more granular in how you set it. If you want an extra 10 minutes on today’s charge you just turn the dial another click or two.

Here’s the timer I have been using. Amazon tells me I have bought five of them over several years.

Picture taken at my professional photo studio (i.e. on my garage floor)

Its a whopping US$9.99 at the time I am writing this. I have been using them for years and they work easily and effectively. Is this a robust solution? No it isn’t. Its just a super cheap little timer. Folks on the internet have taken theirs apart and reported the mechanism inside is not very sturdy. In recent weeks I have found my main one at my home is feeling a little worn out when I turn the dial.

BUT its one hell of a lot better than nothing. And if its this or nothing, spend the ten bucks, get this and hopefully you will be a little safer for having it.

If instead you want to try and do this job with something a little better made, then read Part 2 (coming later in September 2023), where I

Build a Heavy Duty Countdown Timer

BBSHD Programming For The Pedaling Cyclist (2023 Update)

After a few years of incremental refinements, lets re-visit BBSHD programming for pedal assist settings that give you a workout, and are also gentle to the drivetrain.

After A Lot Of Tinkering…

I have written in years past about efforts to develop BBSHD settings idealized for cyclists who want to pedal, and even get a workout. I’ve followed up with revisions here and there as I continued to poke at things.

Things have progressed to the point it is worthwhile to revisit this subject, supplement the original article and share what I think is some progress.

What is here was originally part of my Bullitt hill climber build series, mixed in with stuff about that bike. After a while it became clear I needed a dedicated post, where these settings aren’t buried inside something else so nobody knows they exist.

So. Here we are.


The screenshots below are taken from the widely-used, open source Bafang Configuration Tool originated by Stefan Penov. His software (still perfectly usable) can be downloaded here. My screenshots use Version 2.2b, which was taken up by Laurent V. His later version can be found here. I only use it for screen shots.

To do the actual work, I have long owned a Black Box from Lunacycle which has served me very well. In more recent times I have purchased a cheap ‘programming’ cable, a USB-C adapter and use the Speeed app on my Android phone. This lets me stash the cable on the bike somewhere so I can adjust the BBSHD whenever needed.


There are no perfect BBSHD settings for everyone. I am just showing you mine. Hopefully you will see something useful for your own journey. These are my goals:

GOAL 1: (COMPLETELY) Eliminate Excess Drivetrain Wear

On the internet you hear stories about how a powerful mid drive tears up your drivetrain. It doesn’t have to be this way. When I see reports like this I know someone did something wrong.

In separate articles I make the case that on the one hand, a builder needs to use the right components for the bike to work right:

How to Build A Mid Drive Ebike That Doesn’t Break

On the other hand, making it work right long-term is also a function of the cyclist following a few simple rules.

How To Ride A Mid Drive Ebike Without Breaking It

But on the gripping hand, the third essential ingredient for a 100% reliable BBSHD-powered ebike is to adjust motor settings so it doesn’t behave anything like it did when it came from the factory.

Many of the settings described below are exclusive to Goal 1.

GOAL 2: Set Pedal Assist So The Bike Won’t Run Away From You

A cyclist wants to get a workout while riding. This is difficult with a stock BBSHD, because factory-set pedal assist is so powerful. We want PAS to not overpower us … but preserve the option to do that if we want to take a break.

Goal 3: Easily Shift The Power Curve Up or Down Without Screwing Everything Else Up

This entire settings package – taken together – makes for a refined system. We’ll see how you can easily increase or decrease PAS power output levels across its entire scale, so all of that fine tuning stays in place.

Got all that? Here we go, then.

Fraternal Twins

In line with Goal 3, we will look at two configurations that provide very different levels of pedal-assist power.

One is a low-power setup – developed for use mostly on flat land – for high-cadence, high speed cruising. This setup gives a max sustained output of 400-450 watts on Pedal Assist Setting #9. That is not a lot considering I am using a 30a BBSHD on a 52v battery. With that much power behind it, a BBSHD can easily hold 1750 watts. This is a significant reduction with big implications to range and running the motor well below its redline.

We’re limiting PAS power, not throttle power. If you want to put down 1500w to the ground, use your thumb. Current Limit on the Basic Screen is usually the tool for limiting power output, but that cuts everything across the board. We won’t do that.

I said this config was developed for flat land, but it works on hills if you have the right gears. My Apostate uses this setup and it is a light, short-wheelbase mountain bike with a 40T front ring and an 11-46T cluster.

Small and nimble with a pie plate rear cluster, The 26″ Apostate (a rescued 1999 Intense Tracer) doesn’t need big PAS power.

The other configuration is a high-output setup made for high-cadence, slow-speed riding up the steepest of hills. Its maximum sustained PAS output is in the 950-1000 watt range. This config also works great when you are on flat land: just stay down at PAS 1 or PAS 2. Save the big settings for a rainy day (not literally :D). I use this on my hill-climber Bullitt.

You don’t have to use the high output config on an alpine cargo bike, but it certainly works well with one.

Here’s The Rub

These two configurations are arrived at by changing only one setting. Otherwise they are the same. We’ll talk about the one change at the end.

The Throttle Screen

Start And End Voltage

I am using a commonly-known enhanced range of 11 and 42 (standard factory setting is 11 and 35). This wider range makes it easy to smoothly modulate power in small increments (as low as 50 watts based on what my displays tell me). It eliminates the jerky on/off switch that is usually a BBSHD throttle.

Designated Assist Level

By setting this to 9, we tell the controller to treat throttle peak output as if we are on PAS9. Skipping ahead a little, that setting is unlimited at 100% for speed and current limits, so the throttle has access to full motor power. If you are setting a bike up for your 4-year-old, or Grandma, maybe don’t do that.

(Throttle) Start Current

Start Current for the throttle is reduced to 2%, which is really low. The throttle starts laying on power very gently. You hear a lot about how Bafang motors bang and jerk on the chain. 2% on throttle Start Current ends that. If you find 2% is too gentle, try 5%.

The Basic Screen

What I did with the Speed Limit percentages was simply start at 100% on Level 9, and work my way back in 5% increments down to Level 1. Doesn’t look very scientific, does it?

Some people are looking for Speed and Current Limit settings to give them exactly X output at Y setting based on Z input. My take on this: attempts at precision are wasted effort. These settings are ranges with somewhat fluid boundaries, and will not yield hard limits.

For example: the Speed Limit percentage value is not the percentage of your ground speed. Its of motor speed. As in the percentage of max motor rpms. And those max motor rpms are affected by battery voltage, which is on a curve as the battery runs down.

Thus you see basic increments in my various Limit settings: Over time I have decided these increments give me enough change in performance from one to the next to make them worthwhile, while at the same time not emasculating the low PAS settings with limits too small to be useful.

Lots of room here for changes based on personal preference.

The Assist 0 limits of 1 and 1 are there to preserve the normal function of throttle when you set the screen to Level 0, which disables Pedal Assist. This lets you pedal with no motor support without turning the motor off. Throttle remains available in case of an unexpected need.

The Pedal Assist Screen

This is where the magic happens (click an image to enlarge).

ABOVE LEFT: the high power config. RIGHT: The low-power config. Only Current Decay and Keep Current are changed, and changing Keep Current is not necessary.

NOTE: The screen shots above have a graph that does a decent job of trying to explain how the settings interact and affect performance. Want to know what all these settings do? Look at the graph.

Start Current

Set very low at 2% for the same reason it is at 2% on the throttle screen: kinder/gentler initial engagement (5% is a good Plan B).

Slow Start Mode

Set as gentle as is known safe for the BBSHD controller. Lower numbers here = slower starting and 3 gives me the gentlest motor-safe slope to that curve.

Start Degree Signal

Set to a fairly prompt 4. The problem to solve: starting from a stop at an intersection, while on a steep hill. Specifying a lower number of signals before the motor kicks in makes it start up sooner. Start Current and Slow-Start Mode also figure into this equation so this relatively fast engagement doesn’t cause any drivetrain strain.

Stop Delay

Remains as small as is safely possible to preserve the motor controller. Setting it low like this means when you stop pedaling, the motor stops promptly.

HILL MODE: Current Decay Set To 8

This is the one setting that causes the big changes.

In conjunction with the other settings/screens as shown, changing ONLY Current Decay changes the maximum sustained output of the motor while on pedal assist. A setting of 8 gives maximum output to the drivetrain. Current Decay acts, effectively, as a volume control that goes from 1 to 8.

If it is set to the maximum of 8, Current Decay is minimized almost to the point of eliminating it entirely. This makes sense when riding in steep hills.

Setting Current Decay to a low number to increase its effect makes sense on flat ground. You need less power to maintain cruising speed. But in a granny gear, pedaling like mad and crawling up a steep hill? The last thing you need is for the motor to cut back power. So for hills we set it to 8.

As such, when grinding up a hill at 60+ rpm cadence, and 4-9 mph (7-15 km/h) the motor stays consistently strong.


I said earlier setting Current Decay to 8 almost eliminates its effect. Here’s what that means: As you slowly honk your way up a slope, you get strong, consistent power assist. As you crest the hill and transition to flatter ground, or the hill decreases in slope for a segment, typically you stay in the same gear and spin the crankarms faster (before you think to upshift to a smaller rear cog). That is when Current Decay eases back in again. As you start spinning and speed increases the motor will back off the power.

This will also happen if you just upshift on flat ground and start pedaling furiously. Part of this effect may be due to the low gear you are in and the upper rpm limit of the motor. Since Bafang documents nothing and we are left to guess at everything, its hard to say. But I like it this way as it gives a more natural pedal assist behavior.

FLAT MODE: Current Decay Set To 2

We have taken the same configuration and done nothing more than just turn the volume down.

With the “volume turned down”, pedal assist is still pretty strong at slower speeds with low cadence… exactly what you’d expect coming off a dead stop. But its not so fast you are giggling and leaving people in the dust. You’re starting off only a bit faster than a normal bicycle.

Want more power off the line? Let the throttle help. Don’t do it from a dead stop because thats what kills drivetrains. Give yourself a pedal revolution or two before hitting the juice for, say, 2 seconds.

You’ll know for sure Current Decay is limiting power when you look down on PAS 9 at full speed and see only 400w and maybe 6 or 7 amps on your display.

Stop Decay

This setting is at zero. Once the motor’s assist shutdown is initiated, this setting dictates the slope of the shutdown curve.

I ran some experiments recently as part of an internet discussion. A suggested setting of a whopping 1100 ms (i.e. set it to 110) produced nothing negative. The cutoff happened so fast I couldn’t argue it hurt anything, and I tried to create a problem. It was still a shutdown that happened so fast I couldn’t find a way to screw up.

Keep Current

This is the second of two changed settings, but it is just personal preference, and not necessary to make the big change that Current Decay provides.

I like a strong current reduction when Current Decay kicks in. I have found at high cadence I like the motor to let me work harder than it does with 40% assist. So I kick Keep Current down, get a little more exercise and claw back some efficiency in the process.

(Not) The End

As noted above, there is no ideal suite of settings for any BBSHD. There are also different ways to try and get the same end result (witness how many leave all Speed Limit % settings at 100). I think doing it this way is simpler, and preserves desirable nuances in motor behavior, rather than just zero’ing them out.

DIY Bicycle Front (And Rear) Dash Cam, Part 3

Here is a quick wrapup on DIY, ultra high-resolution bicycle dash cameras. We look at sharing between bikes and issues that go with routine daily use.

This is the conclusion of the topic introduced in Part 1, where started out by looking at the rationale and parts needed for a high-quality DIY front and rear dash camera solution.

Odds and Ends

I originally wrote most of what you see here within the Part 2 Installation and Config post, but for clarity and brevity’s sake its better suited to a short, separate treatment.

There are only a few things you will want to stay on top of when living with your dash cam setup. Lets go over them now.

Long Term Maintenance?

Camera Settings

Every once in a while, the camera will have a brainfart. One morning you will fire it up and it won’t work right. Investigation may lead you to discover it has reset itself to factory defaults. Thankfully, it only takes a couple of minutes to redo them – especially now that you have a guide to use to knock them out quickly.

What I usually see is a message telling me “Memory card is full”. Which should never happen, because the camera is doing loop recording. It is supposed to automatically records over the oldest recording on the Micro SD card. So the card can’t fill up. But it did.

That is a sign that loop recording has shut off. Enable it again and you solve that problem, but if that setting reverted, very likely you will find they all changed. That includes both the video settings changes and the overall system settings. Literally this morning I just had to re-enable all of the video settings, and then also had to go into the system settings and a) redo the date/time formats and b) enable the date/time timestamp… but the camera still remembered the correct system time, so it wasn’t a total loss of memory (still, check the system time just in case) or a full reset.

Riding daily and thus needing two runs per day with the cameras – to the office and back home again – I find this happens about once a month with my older camera models (the one that balked this morning was an older Akaso V50 Elite, which I would not buy again now that the V50x is available). It has not yet happened with one of my V50x’s.


Over time the battery loses capacity. Not a big surprise as that is normal for a li-ion pack. Hooking up the camera to an external power source is a big help for this. The power source just keeps the li-ion pack inside the camera topped up… almost. It doesn’t replace it.

When the camera starts getting old, you start seeing a situation where even if the camera is connected to an external power supply, it still dies mid-ride. That is because running the camera at this high resolution and frame rate means it eats a tiny little bit more power than the power feed can pump back in. As the battery ages, this slight disparity catches up with the camera.

The solution: every week or two on an old camera I need to turn the camera power on and let the camera sit, turned off, and charge its battery. Then its good again for a couple weeks. This can be done while I am charging the bike so its no big deal. Also, since these cameras come with two batteries, switching them one for the other on occasion puts wear on both of them and staves off this issue for quite some time.

I have never had a battery get so worn I considered replacing the camera. So this is an issue but its not the end of the world.

Sharing Cameras Across Multiple Bikes

I shared a parts list in Part 1 already, but lets do another, slightly different one and look at project cost for one bike, then two.

front + rear cameras for single Bike:

Action Camera    US$90.00 x 2
SD Card             20.00 x 2
Front Camera Mount  18.00
Rear Camera Mount   12.00
27000mah Power Bank 30.00
USB Cables (2 pak)  11.00
Total Cost         291.00
Cost Per Bike      291.00

Front + Rear Cameras For Two Bikes:

Action Camera     US$90.00 x 2
SD Card              20.00 x 2
Front Camera Mount   18.00 x 2
Rear Camera Mount    12.00 x 2
27000mah Power Bank  30.00
USB Cables (2 pak)   11.00 x 2
Extra Scuba Box      13.00 x 2
Total Cost          358.00
Cost Per Bike       179.00

What we’re doing above is buying two of everything to mount the cameras, but just one power bank and one set of cameras.

To move from one bike to another we just pop the cameras and power bank off of the one bike (remember the scuba boxes make for quick-detach) and right back onto the second bike in literally just a few seconds.

US$291 sounds like a lot until you look at your alternatives. Tally up the features you won’t have when buying a commercial bespoke solution, versus this one. We went over the alternatives in detail in Part 1. If you add to it the fact that it is easily made portable, works for two bikes and gets your costs down to US$179 per bike… you are way ahead of the game.

Extrapolate this out to as many bikes as you please. For three bikes, you come up with a total of US$425, which yields a per-bike cost of to US$142.

Video Editing Software

Recording your travels, you might want to look them over (or maybe you had an accident and need to show it to the cops or your lawyer). How do you dig the files out?

First, the easy (and almost useless) way: View them on your camera. You can scroll thru the vids and tap on one to run it onscreen. But the screen is like a 2-inch diagonal TV set, which can’t show any level of detail. You need to export the file to your PC to view and zoom in on a big screen monitor.

When you bought the camera, you also bought a MicroSD card to hold your files. Remove that card from your camera and plug it into a MicroSD card reader. This is one of the ones I have, so I know it works.

Plug that card reader into your PC. It will come up as a USB drive. Like a thumb drive. You will find files in three types.

THM files

These are Thumbnail files. These are merely the thumbnail images you see when scrolling thru the video list on your camera.

LRV files

These are Low Resolution Video files. I mentioned earlier a recorded file in 4K30FPS is enormous. An LRV file is a playable low res version. If viewing a video on the tiny camera screen, this little file is used. Otherwise, these aren’t going to be of any use.

MP4 Files

This is your high resolution recording. That will be obvious when you see the enormous file size. MP4 is a format this is a bit nebulous in terms of its use of standards, but you should be able to load it into common video software/freeware.

Copy the files to review to your PC’s hard drive. Load them into your video software. My Windows 10 PC came with Microsoft Video Editor pre-loaded. I use that to expand the video to full screen and play it back. I can pause it and click thru frame by frame until I can read a license plate of a car going by. If I am viewing the upside-down rear camera view, a couple of mouse clicks rotates the view to right-side-up.

Finally, once I find a still image that displays what I need, I can store a screen shot to hand over to a lawfully interested party.

Wrapping It Up

With any luck, all you will do with these cameras is install them, turn them on at the beginning of every ride and off at the end.

But if you ever need a witness after an accident, a super high-resolution, 170-degree forward and rear-facing, image-stabilized record of the event is there for you – and if you ever need them, they will be more than worth the time and effort it took you to set them up.

DIY Bicycle Front (And Rear) Dash Cam, Part 2

This installment will focus on the installation and configuration of an ultra high resolution (4K and 30fps) DIY front and rear bicycle dash camera system.

This is a continuation of the topic introduced in Part 1, where we went over the rationale and parts list needed for a high-quality DIY front and rear dash camera solution.

Lets Get Started

We’ve purchased and received our parts. Lets install them and get everything set up. This article is going to be rather straightforward and by-the-numbers, as we already went over the reasons for rolling our own dash cam solution in Part 1.

Before we start bolting everything on, we will modify the scuba box.

The What?

Yes I said ‘scuba box’. Pretty much every budget action camera comes with a waterproof box as an included accessory. It lets you take the camera to the bottom of your swimming pool or lake or whatever. Putting the camera into the box makes it waterproof (and somewhat crashproof, too). Thats great, but what we really want is to make it easy to remove from the bike.

Most cameras have a threaded hole meant to interface with a standard 1/4″ camera tripod fitting. You can use that to screw the camera down onto a mount directly.

We don’t want to do this. When you are routinely using a camera on a daily driver bike, you need a quick and convenient way to take if off.

Why Take The Cameras Off?

It was literally just yesterday when, at my local Costco, I was beginning my process of locking the bike. A curious onlooker leaning against his parked car asked me “You aren’t going to leave those GoPro’s on there, are you?”

“Hell no” I Replied

“They go inside with me, and back on when I come back out.” I showed him how I just opened the scuba box door, disconnected the USB power cord and into a little go-bag they go (I re-use the bag that holds my bike lock), along with my removable taillights, tool bags and power banks. I also noted they are not expensive GoPro cameras. But still, two of them would be a pretty nice haul for sticky fingers.

And THAT is the real reason for the scuba box.

But its not quite ready yet. When I first started using cameras like this, I relied on their internal batteries for power. I quickly learned it was a pain to recharge the battery so frequently. Besides, battery life could be insufficient to get through a single ride.

The solution is to plug the camera into an outside power source. The camera still runs on its internal battery, but that battery is constantly topped up by the power source you connected. It (almost) never runs out and you can forget about it. More on this below.

So plugging the camera in is great, but we encased it in a watertight box, so you can’t plug anything in. Unless you…

Take A Drill To The Scuba box

The V50x camera – and every other action camera I have used – has a USB Micro-format combination data and charge plug. To get to that plug, we need to drill a slightly oblong hole in the box (speaking of which, when buying USB cords do not pick one with a big blocky plastic guard around it, or you’ll need to drill a huge hole).

In the left picture above, the hole is bigger than it needs to be. Oops my bad. But even so, an oversized hole like this should not cause a problem in even a heavy downpour. Still, you should be more careful than I was.

I said ‘oblong’ hole. To get that, I a) drill a round hole and then b) press against the side of the hole with the running drill. That grinds away just some of the top and bottom of my once-round hole. Then I incrementally test-fit and expand the hole some more until the cable fits snugly. There’s usually more hole than I need, but it never is so much it compromises the box’s structural integrity.

My Milwaukee step drill bits (I have this set) go thru the boxes cleanly in hot-knife-thru-butter fashion. So its easy to over do it. I have never ruined a box, but still be careful.

This set is part number 48-89-9222 and is the cheapest step drill set Milwaukee sells from what I see.

You can also use a simple old school drill bit and work it from side to side. Conventional bits are more difficult and leave more mess in terms of shavings. Once you get the hole drilled the rest is pretty simple.

Mount The Front Camera

First, this mount is more-complex than necessary. But it is what I consider to be a more ‘evolved’ method. I use a handlebar extension to raise the camera up high. This makes it more obvious to cars around me. I am using the following components, from the top down:

This thing is really up high but is not in my way
  • The Akaso V50x camera, inside of its scuba box. You can see the USB Micro wire coming out of the side connected to the USB port of the display, providing continuous power.
  • The adjustable forward camera mount. I added a red adjuster knob to it.
  • The camera mount is attached to a short handlebar extension, angled up to about a 2 o’clock angle. This helps because I need to mount a special light there, thanks to the particular setup of that bike. For your needs we only care about the extension because it raises up the camera. Zoom in. You can see it has two mounting arms (the product sells with just one). I had an extra. If you don’t, buy a second one and use the arm that comes with it. You could also buy a longer extension as those come with two arms, but I wanted to keep it small.
Step back from the bike a bit. That camera – raised up by the handlebar extension – really sticks out. Which is totally the idea here.

If you don’t have to mess with the added complications of a display and a light sharing real estate with the camera, you may still want to use that extension to raise the camera up. It is solid, doesn’t jiggle and helps make it obvious to others a dash camera is in use.

Keep It Simple, Stupid!

I have done a lot of these with a simpler mount – no extensions. The bottom-most picture below is an almost identical bike with the same displays and even the same funky light. That time I mounted the camera to the side.

For all of these bikes above, I just bolted the camera mount directly to the handlebars

If you are going this simpler route, it may be smart to put the camera on the left side as you face forward, where it will be more visible to neighboring vehicles. I hadn’t figured this out when I did these bikes.

Mount The Rear Camera

There is much less going on in back than on the front mount. I’ve only found one ‘best’ way to do this:

  1. Attach the saddle rail camera mount.
  2. Attach the scuba box to the mount, with the camera inside.
  3. Attach the right-angle USB cable that feeds power to the camera.

Pretty easy. You will spend more time routing the USB cable to your power supply so it stays tidy.

Above: That short cable running thru the frame and seat rails is a seat leash, which, coupled to the dual-bolt seatpost clamp, makes it more time-consuming to steal the saddle and seatpost.

What Power Supply?

There are a few different ways you can go here.

Use the Internal Camera Battery

This is the way I did it for the first couple of years I used these cameras. At the end of a commute into my office, I pulled the camera from the scuba box and plugged it into a USB charger. At the end of my workday at home I did it again.

This was before I started drilling holes into the boxes, but we’ll get to that. When going this route, it is the least convenient because of the charging, but it is also the easiest to install with no extra effort.

Use An External Power Bank

Charging the camera twice a day was a pain on a daily driver bike. So I moved to an external power source. Since I still needed that scuba box for ease of removal, I drilled a hole in it so I could plug into the camera.

This is where my power banks go on both of my Bullitts

One power bank can easily power two cameras. A big power bank can do it for a long time. I like to recharge them once weekly, every Friday. I use a big power bank, but that big bank also powers other lights, so for just a camera you can use something smaller. Your mileage may vary.

My project parts list includes two options, both of which I use personally. One is a high-quality name brand. The other is a low-cost, no-name product with good reviews that is working just fine for me.

Use The USB Port On Your Display

This one is kind of a no-brainer. It makes for the cleanest setup. You can select options on the camera so when you turn the display on and off the camera goes on and off with it. Also you can skip the weekly power bank charges since you are using the main ebike battery.

However, not every display has a USB port. None of them have two ports to accommodate a front and rear camera. I have 2wd bikes with two displays so I can cheat, but thats true for almost nobody else.

You may want to just hook up one camera to your display and one to a small power bank. Or if you are handy with electronics, wire in a USB buck converter to your main battery for multiple USB ports.

Camera Settings For Dashcam Use

There are a variety of ways to fiddle with settings. In particular the power-on options to make the camera turn on and off automagically when you plug it in, power up your ebike display or turn on your power bank. I have found the most reliable method is where I manually start things up and shut them down. Letting the camera manage it, I’ve had one too many experiences where it has decided to take the afternoon off and shut down mid-ride for no apparent reason.

Driving Mode vs. Video Mode

Driving Mode is one of the 9 main modes that the V50x camera has for startup. Driving mode is a dedicated dashcam mode that – in theory at least – helps makes the camera completely automatic. When it senses power, it powers up the camera and immediately begins recording. When external power is no longer fed to it, it shuts down. That means if your ebike display comes on or shuts off, so does the camera.

That sounds great but in practice on these cameras, it literally does not work for some reason. What happens is the camera powers on exactly as expected, but then within seconds (before I have a chance to climb on the bicycle and start moving) it shuts off. Its not motion-activated because riding the bike does not trigger it to start back up again. If there is a way to make it work as advertised, the instruction manual is completely silent on it.

I prefer to use simple Video Mode, where I use the on/off and recording start/stop switches myself. Done that way it always works with no surprises.

For the settings below, if I do not list something that is on the menu, the setting is left in its factory default state.

Video Settings

This is the best setting for getting clear readings on a moving car’s license plate.
Image StabilizationOn
You need this for jiggle-free video
According to the manual, this is the same thing as Image Stabilization. I turn them both on for the smoothest possible recording.
Loop Recording Time3 minutes
This sets how long each video snippet is. You want short loop recording time. A 3-minute video in 4k running at 30 fps will be well over 1 gigabyte in size. A longer loop sounds like a great idea until you try and work with a two gigabyte file in your video software.
Audio recordOn
It can’t hurt to have sound to go with your recording. Audio will be muffled thanks to the scuba box encasing the camera.

System Settings

Soundsall enabled
This just turns on all audio feedback to your touchscreen presses.
Distortion CalibrationOn
According to the manual, this is a helper for Image Stabilization. It narrows the field of view slightly.
Angle170 degrees
The widest angle possible. Since we’re trying to gather evidence in case of some sort of traffic accident, more is better.
Diving ModeOff
Do not mistake this for “driving mode”. It compensates for the lack of red light while diving under water.
WDR (Wide Dark Range)On
Allows greater detail in shadows when an image contains both bright and shadowed areas.
Auto Power OffOff
The camera can be set to power off during inactivity. Turning this off prevents the camera from deciding it needs a vacation.
Screen Saver1 minute
This just shuts the screen off to conserve the battery
Date Formatyyyy/mm/dd
Personal preference. The format used for the onscreen date stamp
Date StampDate and Time
This sets the recorded onscreen stamp to show both date and time.

Wrapping It Up

With any luck, all you will do with these cameras is install them, turn them on at the beginning of every ride and off at the end.

But if you ever need a witness after an accident, a super high-resolution, 170-degree forward and rear-facing, image-stabilized record of the event is there for you – and it will be more than worth the time and effort it took you to set it up.

We’ll cover odds and ends, which includes video software to extract your little home movies, in Part 3.

DIY Bicycle Front (And Rear) Dash Cam, Part 1

You know dashcams create a record of evidence. Surprisingly, they are also visible to nearby drivers, and become a deterrent just by being in plain sight.


I have been using inexpensive action cameras (i.e. GoPro clones) for years as dashcams on my urban commute and cargo ebikes. Going DIY, I get much higher video quality and spend a lot less money. Once you figure out how to set them up, its an easy process.

I started doing this after I was run down (a T-bone SMIDSY) by a negligent driver in 2017. The police report worked hard to blame the victim (me) for traveling at low speed (about 15 mph in a 40 zone), with three headlights on, in the designated on-road bike lane. I even made eye contact with the driver while she stopped before pulling out and into me. I found out the hard way the driver was looking through me, not at me.

What the hell is a SMIDSY?

At least the police report conceded the driver was the cause of the accident – and tried to take it back a bit by stating that the safe speed for a bicycle “may have been 3 mph”. Yes, thats right… three.

Unfortunately, experienced urban cyclists will recognize the problem. Motorists often get every benefit of the doubt when they run down a cyclist, regardless of the consequences of the motorist’s inattention. I was carted off in an ambulance.

Cyclists Need an Irrefutable Witness

Over the years, I have learned a few things about what kind of camera is well suited to this job, how to best install it, and how to configure it so it is as easy as possible to use on a routine basis. During a recent online discussion on the subject, it occurred to me this would be a good topic to lay out for people all in one piece.

Lets make a centralized parts list right off the bat, so its easy to come back to. We’ll get into what each item is and why it is on the list further on:

What About External Perception?

As alluded to in the lede above, having visible cameras does more than just preserve an evidence record (I tell people who ask about them – only half jokingly – they are there to tell the police who killed me).

My v1.0 mounting of my front camera on my white Bullitt. This is the best, most functional layout of the light, (placing it up high) and the camera.

Something I have experienced has been echoed to me informally by other cyclists: People treat a cyclist differently when the camera is there, blinking its little red “I’m on” light. Drivers behave with a bit more civility. Is this a scientific observation? Nope. Is it a universal benefit? Nope. But it does look as if, when people know that Little Brother is watching, they are less inclined to brush you back or run you off the road.

Camera mounting v2.0 happened not to get better performance out of the camera, or the front headlight, but to make the camera stick out more obviously visible to nearby drivers.

Once I realized my own perception of that phenomenon was not unique, I decided to supplement front cameras with a second, rear-facing one. Yes I want to get video of an oncoming vehicle that may do a bad thing. But even more so, I want that driver to maybe see the camera and … sober up a little?

Worth mentioning: Cameras like this have been used for years by motorcyclists, and I think motorists have grown somewhat used to them as a result. I have yet to see a volatile reaction by anyone getting mad I am recording them as they go by.

However, I do respect others’ privacy, and I will not be showing any stills taken from my cameras that show clear license plate views (which is the high standard we are going for here).

What About Turnkey Products?

Turnkey solutions exist for cyclists right now. Perhaps the original is the Cycliq Fly. One look at the price for front and rear cameras may give you pause. But if protection is afforded, price is secondary.

Instead, when evaluating them dig a little deeper at the camera resolution. The front camera provides a best resolution of 4K @ 24 fps, with 6-axis electronic image stabilization. That is pretty good but – in 2023 – unremarkable. The rear Fly6 on the other hand gives you a 135-degree view at a resolution of either FHD (1080p at 30fps) or HD (720p at 60fps). Their rear camera provides no mechanical or electronic image stabilization.

The Cycliq product also incorporates an app, and each version also incorporates a light.

Garmin makes a bike camera system as well. Its rear-facing Varia is a combination of rear light, camera and actual radar. The radar senses an approaching auto and warns you of its approach. Rider discussions I have seen report the radar really works. Insofar as the camera is concerned, its best resolution is 1080P @ 30 fps. There is no front camera option.

Bottom line: A turnkey solution for both front and rear is going to cost rather a lot of money. It may or may not provide a video solution that allows resolution and stability that will capture a legible license plate. I consider that license plate essential as it may belong to a vehicle that left the scene long before you are carted off in an ambulance.

In my own personal experience, I have tested the video resolutions and frame rates described above on cameras and consider them failures in the license plate reading game. They will be fine for capturing what happened, but if the car leaves the scene, law enforcement officials won’t be able to identify the vehicle from the plate number.

What About DIY?

It turns out ‘generic’ action cameras have all the features you need to make a dashcam. You just have to know how to set it up, which is not difficult. They will give you a highly detailed, electronically-stabilized screen resolution (you cannot take stabilization in all resolutions for granted and have to carefully review camera specs to confirm this).

High up is where a front camera usually goes on my bikes. Thanks to the 170 degree lens angle on my preferred camera, putting it a bit over to one side or the other on the bars is a non issue.

I have bought a number of cameras over the years. Some have been expensive (GoPro), some have been really cheap (low end Chinese GoPro clones) and some not so cheap. I will skip any further mention of that learning experience and just jump right to the one that works best for me now – in 2023.

The Akaso V50X Action Camera

  • In 2023 as I write this, this model has been around for awhile. I bought my first one in early 2021. So it has a feature set that is not state-of-the-art.
The camera, shown inside its waterproof scuba box, mounted with the front mount in our parts list. The red knob kajigger is some extra added bling. The wire sticking out? We’ll cover that in Part 2.
  • In 2023 as I write this, this model has been around for awhile. That means it is not a premium priced product. I bought my most recent two on sale for US$79.99 each. MSRP is US$99.99.
  • The camera uses a native 4k resolution with a native 30fps frame rate. There are other rates available going up to 60 fps, but in side-by-side testing, the 4k/30fps with image stabilization enabled gives the best license plate readings. Note I said ‘native’ above. That means there is no on-board interpolation to up- or down-rate the image. Since ‘interpolation’ means ‘adjustment’ and ‘approximation’, native processing modes should give the camera’s cleanest end result.
  • No proprietary software is needed to play or process the video. I use the movie software included with Microsoft Windows 10 to view and edit the files.
  • Electronic Image Stabilization (EIS) differs in effectiveness from brand to brand. EIS on the V50X is very effective. I almost can’t see how it could work better. I have tested it on potholes and curbs and the video remains steady.
  • Settings are available to loop record, which is a critical feature for a dashcam application. The camera records in short time-loop intervals (shorter is better… we’ll discuss why later), then starts another file. When the SD Card storage fills up, it records over the oldest files, so you never have to flush it clean when it fills up.
  • Settings are available to turn the camera on as soon as it receives power. A driving mode makes camera startup and recording automatic, although I prefer not to use it.
  • Out of the box, the V50x comes with a zillion accessories. Way more than you will ever use. The one accessory that is critical is included: the waterproof scuba box (not needed for waterproofing… we’ll get into that later). You can buy a second box cheap on Amazon to share a camera across multiple bikes.
  • Its got a slightly bigger battery than other models in the Akaso line (which I also own). We’ll discuss a setup that bypasses the battery later.
  • Having had a V50x in service since 2021, and other Akaso cameras since before then, I have found the brand produces a reliable product.

A shorter version of the above is:
the V50x is cheap, durable and does everything you need for a bicycle dashcam.

SanDisk Extreme Pro Micro SD Card

You need this for the camera to store its video files. No camera comes with them and they have to be purchased separately. With a 200 mbps write speed, this is the fastest card you can get your hands on right now. You need big write speed to support the 4k/30fps mode on the camera. And since Micro SD cards are cheap, a relatively gigantic 128GB card is only US$20.

According to the instruction manual, the V50x camera only officially supports 64GB cards, but the manual also says some 128GB cards will work. This one works. I use them due to the fast write speed, not the storage size.

The Front Mount

I’ve tried a few mounts and, once I settled on this one, have stuck with it for years across several bikes. It is all alloy, no plastic, and mounts rock solid on the bars. Over time it does not loosen up, and keeps the camera in place regardless of bumps and bonks as I go down the road.

It does rotate on its horizontal axis by design, but there is a strong detent in place so it can’t happen accidentally. This rotation lets you put the same mount at different positions on a swept-back bar and it still points straight forward.

The Rear Mount

I have only recently started doing rear cameras and this mount was exactly what I needed to make it happen. It is all aluminum with stainless bolts, and mounts solidly to the saddle rails. It doesn’t move over time. Its easy to mount the camera to its GoPro-compatible mount.

With this seat rail mount, the camera in its waterproof case tucks right in under the saddle where you’ll never know its there.

This mount does make it necessary to mount the camera upside-down, but all of the video-editing software I have ever used – and I always use something simple and free with minimal features – allows you to easily flip the video right side up. The time stamp onscreen will be upside down but we aren’t trying to be Cecil B. DeMille here … its just a dashcam video.

The saddle mount positions the camera so it sits with plenty of room to clear the Kinekt and Thudbuster seatposts I have used it with.

The (Optional) Power Pack

There are a few ways to power your DIY dashcam solution. One way is to just use the in-camera battery. Another is to run a little USB cable from the camera to your ebike display’s USB port. That will give you a constant power supply that never runs out. If your display does not have a USB port available, the next best step is to fudge it and use a USB power bank. I have found it is much more convenient to use a big power bank and charge it, say, once weekly, than it is to use the in-camera battery that is going to need recharging after every single ride. I’m including links to two different – and big – power banks.

I do not use power banks this big to run just my camera. These banks have three USB outlets. I use all three – two to power my LED COB light banks and one to power one of my two cameras. I have a USB display powering the other. So for a more normal bike, one such power bank could power two cameras no problem for a week of long, daily commutes. A much smaller power bank would probably be fine, too; especially if handlebar bag space is at a premium.

I am linking to one Anker power pack that is a top quality item and priced accordingly. I’m also linking to one much cheaper and – on paper at least – is just as capable and 1/3 the price. I can’t be sure if it is as reliable as the Anker but for twenty bucks versus almost seventy… I figured it was worth a shot. I have only been using it for a few weeks so far.

Misc USB Cables

There are a half-dozen different ways to wire these things up. If you are doing a direct wire to a power bank or display on a rear camera, a long-ish USB cable with a right-angle plug at the camera side is a good choice. If doing a front camera mounted to the bars and tied to the USB plug on your handlebar display, you can get away with using the short freebie cable that comes with the camera. If things are lined up just wrong on your display, you may want to use a short 45-degree USB extension. We’ll go over a few variations …

when we tackle camera installation and configuration in the next installment. 🙂

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