Quite some time ago, I produced a series of charge status charts for a variety of common lithium-ion battery voltages. They’ve become a fairly common link to help folks out on various Facebook groups who use these battery voltages in their ebikes.
I built them using Google Sheets, so they are not web pages, which I suppose has kept them from being widely linked in search engine results when people are looking at such things.
Here for the first time are direct links to the charts on a normal web page.
Remember, these charts show ballpark values that are as numerically correct as they can be. Individual cell characteristics will cause variation in the numbers here. Read the notes on the chart for a little more detail. Bottom line: cells degrade differently, but imperfect charts like this are still good baseline references. Use these and teach yourself how to read the voltage gauge on your display screen.
36 Volt (10S) Battery Charge Chart
The first link is to the lowest voltage: 36v. Generally this is the lowest voltage you will find on an ebike. Note that its called ’36 volt’ but really that is the ‘nominal’ value. A 36v battery is actually fully charged when it is at 42.0 volts.
48 Volt (13S) Battery Charge Chart
The next common size is 48v. These batteries are fully charged at 54.6 volts.
52 Volt (14S) Battery Charge Chart
The next battery voltage is 52v and very common. 52v batteries will work on systems designed for 48v, and why is easier to understand when you become aware that a ’48v’ battery really tops out at over 54 volts. A ’52v’ battery tops out at 58.8v, so it essentially lets you use a 48v system for a longer time at higher voltage levels that it is already designed to utilize.
60 Volt (16S) Battery Charge Chart
With a 100% charge voltage of 67.2 volts, when you have one of these you are more or less now using high voltage electricity
Please take note: What I am describing here is not for everyone. You need to do this right. If you have any qualms about doing this kind of basic electrical work, don’t try it. Mean Well LED power supplies have been used by the DIY ebike community for years. The concept is not new. The weak link here is you and if you screw this up consequences could be profound If you know your way around a crimper, or a soldering iron… great this will be easy. Kid stuff. If not, don’t pick this project as your first learning experience.
Why reinvent the wheel here? What benefit could be gained?
Ebike battery chargers tend to be dodgy. The interwebs are filled with stories of frequent flyers whose chargers keep dying. Its either a dead fan that in turn lets the charger heat up and fry, letting the smoke out of the internals (never a good sign) or perhaps the most common: the charger stops cutting off at its cutoff voltage and keeps on charging … with potentially catastrophic results.
So… what is better? You can see that in a popular commercial battery charger: The Grin Satiator. Its so efficient it needs no fan to cool it (or to fail). It is also largely weatherproof and highly reliable. The only demerits it gets from users – which have largely gone away over time – are programming/firmware issues.
Oh and its cost is US$300+ once you figure in a programming cable, along with a couple of adapters. I bought one. It works perfectly. But with an AWD bike with 2 batteries that I ride every single day and charge both at home and at work, I found convenient charging means walking up and plugging in. Not carrying chargers with me, unloading them, setting them up etc. So 2 batteries x 2 locations = four chargers. $300×4= not happening. And I carry a charger with me in case I get stranded. $300×5=crazy talk.
What to do? Use the same core hardware that gives us the $300 charger but without the fancy user interface. That costs around $40. We won’t have a fancy display screen or onboard memory, but it will still be adjustable with a screwdriver.
I have worked with three different models that can serve my purposes. Remember that volts x amps = watts and this will be important when figuring out what to set your charger for:
Available regularly on Amazon for about US$55
Rated to 150 watts
Rated as adjustable from 40 to 56v but actually adjusts from 39v to 58.1v
Usable as an 83% to 100% charger for a 36v battery
80% to 100% for 48v battery
80% to 96% for a 52v battery
Minimum amperage selectable is about 1a
Lower wattage rating means it must be set to lower amperage on 52v batteries (2.5a max for a 52v battery)
Designed for LED lighting and ‘moving sign’ lighting applications
IP65 rated for indoor and outdoor use.
Usable at EU or USA voltages.
Mean Time Between Failure (MTBF): 303,700 hours. Yes, really.
This is the Big Daddy. As in bigger and heavier and more power output.
Street Price around $90. Often available on EBay for around $50, even down to as little as $25 each if someone is selling off a pair of them wired together as Zero e-motorcycle chargers.
Essentially same specs as the HLG-185H-54A but is instead rated for 320 watts
Current can only dial down to about 2.0 amps. But the high wattage rating means it can be dialed UP to make it a 5 amp charger (only aftermarket battery plugs like XT60 or Andersons are able to safely handle this current level).
MTBF: 157,100 hours (just under 18 years of continuous use)
The 320H units I have bought on the aftermarket were originally wired together in pairs in series and used as onboard 115v Zero Motorcycle chargers
SIDEBAR IP65 Enclosure – IP rated as “dust tight” and protected against water projected from a nozzle. So these chargers are safe with:
Garden hose spray (or heavy rain) – Yes
Ocean waves – Maybe
Bottom of fish tank – Hell no
Myself, my bikes have 52v batteries. I do use a couple of CLGs at work for my charging station there but only because I hadn’t found the HLG-185’s yet. The HLG-185’s are ideal chargers as they can charge at levels safe for the Sondors battery plugs (3a max) and can handle any voltage asked of them for a 48v or 52v system. If you have an aftermarket battery that does not use the pin plug as do the Sondors batteries, then you almost certainly have an Anderson Powerpole, an XT60 or an XLR connector. Those plugs can handle the higher amperage the 320 is capable of delivering. I use a 320 as a travel-with charger under the theory that if I am stuck somewhere I want to grab as much charge as I can, as fast as I can. But a 185 is perfectly capable of being a 3a charger and weighs probably half what the 320 does.
So… enough details already. Lets make a charger! Here’s what we need:
A Mean Well power supply. The process is identical for all models.
A pigtail’d grounded electrical plug. They are sold on Amazon typically as replacements for corded drills and similar power tools. NOTE: I am using a USA standard plug, but these units are made to accept worldwide voltage/current so just go to your local hardware store and choose your local version of a pigtail’d, grounded power cord if you live outside the USA. Oh, and read the spec sheet to confirm what I just said applies in your country.
A digital watt meter to tell us what we are outputting to the bike. For almost all of my chargers I use $15 inline watt meters. This is optional but very desirable.
An interface from the charger to the battery. I will use an XT60 as the direct connection, which is what a lot of aftermarket batteries use. You can then plug just about any adapter into that for your Sondors or whatever else you have. Note in the picture above, bottom center just to the left of the little adjustment screwdriver we will keep with the charger, that there is a pin plug adapter for use with Sondors batteries. That one came from Luna Cycles.
A note on battery/watt meters. Here’s the short version: They suck. Or more accurately they are oftentimes off by a bit, and there is no way to calibrate them. Its not uncommon to see a battery meter accurate to within 2%. That sounds ok unless you are charging to 58.8v, which could be 59.98v with a 2% error and that is very, very bad. So you want to take a multimeter or similar *known safe benchmark* (in a pinch the reading on your LCD screen will work once you have disconnected any charger from it) and use it to learn where your chosen meter is in terms of its accuracy. I do this and then I take a labelmaker and make a label telling me how much a meter is + or – actual voltage.
So for example, if my target voltage for a 52v battery is an 80% charge of 55.4v, and my watt meter is reading 0.50v higher than it should be, then I create a label that says
UPDATE: This link is to one of many cheap Chinese watt meters. The last two I have used, purchased across a span of 4 months, exhibited a new and consistent behavior: Plug them in and they are WAY high, by like 1.2v. But sit and watch the meter over a span of about 5-10 minutes and you will see it slowly auto-correct itself down to a steady reading. This steady reading will still be off by a bit but not so bad… these last two meters were both off by only about 0.20v… so I recommend these as your best option – and recognize they have a calibration stage at startup that you need to wait out.
So now, we have our parts in hand and its time to assemble them. In order the steps are
Step 1 Attach the pigtail’d cord to the input side of the Mean Well unit. For the USA plug and the Hanvex drill cord I have been using, the wire sequence is green (cord wire) to green (charger wire) for ground, black (cord) to brown (charger) for AC+ and white (cord) to blue (charger) for AC-. Note that the wire colors are noted on the charger left side, but as ACL and ACN. DO NOT SCREW THIS UP. These are international standard designations and colors which as usual the U.S. does not follow. If you want to check my work, start googling. Myself, I use marine heat shrink butt end connectors to connect the wires. I also use rather expensive electrician’s-grade crimping pliers. There is a big difference between proper crimping pliers and … well, pliers. Use the right tools for the job. After I crimp, I heat shrink the connectors, add heat shrink around each individual wire and then do a heat shrink around that entire assembly. How you do it is up to you (i.e. soldering or whatever). Remember that this is mains power you are fooling with here so get this right.
Step 2 Attach a battery side plug. In this case I am using a male XT60 which both works for my aftermarket batteries that have female XT60 charge plugs, and my bottle batteries where I use my XT60-to-pin-plug adapter. Same procedure as in Step 1 although a little simpler as there are only two wires. Note that some of these charger units do not use red and black wires. If you are not familiar with what the colors mean, the casing on the unit specifically tells you which wire is which (V+ and V-).
When you are done, you will have something looking like this:
Step 3 OPTIONAL – attach an inline watt meter to the output side of the Mean Well unit. This is your power display. I call this step optional because you could just calibrate your charger output once and not use a meter to monitor progress (easy enough to turn on the bike display during charging, which will hurt nothing). Myself personally, even though meters are pesky insofar as getting them calibrated, I prefer to have a real time progress monitor I need only glance at. NOTE: Source side of the meter gets connected to the charger. Load side goes to the battery.
Step 4 OPTIONAL – make an extended output cord. Essentially one big extension cord on the battery side. You’ll know real fast if you’d like to have one of those as whatever you made doesn’t reach. You could just hardwire this to your output lead on the charger. But then you are stuck with that length alone. I prefer to make a cable as I have no problem using a couple of 12 AWG XT60 pigtail ends to make a dedicated extension.
Step 5 Connect an interface to your battery. For a Sondors, this is a pin plug connector. For many batteries the generic standard is a male XT60 connector. You can either buy a direct-connect bottle battery adapter (see link) or connect a male XT60 pigtail and then buy an XT60 Female-to-bottle adapter. Doing it the latter way makes your charger able to connect to any battery (if you have another battery with say XLR connectors you can make an XT60-to-XLR adapter via a couple of pigtails). You just swap in the adapter you need. In this case I am picturing a Luna-sourced XT60 female to pin plug adapter. A different source for the same thing is in the parts list below
Step 6 Go out and buy a little Phillips head screwdriver. This tool will live with your charger forever so you should buy a new one unless you have an extra already. Its a must-have for the next step. Also required if you plan on changing your settings (lets say you want to charge 80% one day and 100% the next).
If you have performed all of the above steps, you now have a parts pile that looks like this (well sort of, the meter and the charger have already been labelled with calibrations but just pretend we haven’t done that yet):
Step 7 Dial in your output voltage. Once you have connected an AC plug, and a battery side connector AND connected the inline watt meter, you simply have to plug the new charger into the wall. Amps will read zero and volts will read whatever the unit is currently set for. See the little rubber whatsits that are capping the voltage (Vo ADJ) and amperage (Lo ADJ) adjustors? Pull those off and stick the screwdriver into the Vo ADJ hole. Twiddle it around gently until you feel it seat into the adjustor. Now turn it first one way, then the other. Watch the voltage readout on your meter. One way goes up, the other down … and the directions are different on my 185’s and 150’s vs. my 320 so you figure out what direction does what yourself with your own unit.
Step 8 Calibrate your meter to reality. Remember what I said above about meters. You need to figure out how far off your meter is from your display. As you can see if you look closely above, this meter is off by +0.50v. Thats a fair bit. The good news is when these types of meters are off, they are consistently off so you just need to know by how much (and if you can find a meter that is consistently accurate tell me. I can’t find one at any price). this is a pain but you only have to do it once.
Step 9 Dial in your output amperage. OK… moment of truth time. You are plugged into the wall. Time to plug into your battery. Maybe you should do this out in a field with a long extension cord. Don’t do it in the baby’s nursery or in Grandma’s bedroom while she’s asleep. Plug the battery in and now watch the meter. The voltage switches to now show the battery state of charge. The amperage comes to life and shows the current level (amps) being fed into the battery.
Once again, like you did with the voltage adjustment, use your screwdriver this time in the Lo ADJ socket and twiddle it until you see the safe amperage rate you safely want to safely run your charger safely at. Did I forget to mention safety? And volts x amps = watts ? Pay attention and get this right. If your meter is off – especially if it is reading lower than actual voltage – you will want to find out by what percentage it is off and adjust your indicated meter amperage less that percentage amount.
IMPORTANT SAFETY TIP:
Your charger does not switch its power feed on and then off like a light switch. Instead, it will slowly ramp down its current delivery level (amperage) as the battery approaches your target voltage. So that means if you plug in a battery that is fully charged or nearly fully charge, you will get a really tiny reading of current going into the battery – and this will give you a false idea of the amperage your charger is set for. Because of this, when performing calibrations you must have a battery that is at least a couple of volts low. At least. If you are charging to 54v (100% charge on a 48v battery) then plug in a battery at no higher than, say, 50v state of charge.
If you are using a pin plug, NO MATTER WHAT make sure this value does not exceed 3 amps. The plug can’t safely take more. Again, remember that volts x amps = watts. So if your 185w HLG-185 is feeding the max of 3.45 amps, that means at 58.8v it will be sending 203 watts which exceeds its 185w rating and thats VERY bad. Here again. Use your brain and don’t screw up. Best to leave a safety margin. For example I have one of these set to a ‘full’ charge of 58.3v and 3.0 amps. 175 watts.
Step 10 Add a carrying case? Your basic MOLLE water bottle bag will fit this all beautifully. the slightly larger Condor bags available on Amazon will do so with a little more fudge room. I got two green ones on sale for $5 and $8 respectively. Sometimes they are more. Happy hunting. In the end what do you have? A charger that you can expect to be reliable literally for years. Not necessarily cheaper, but dependable. If you buy this once you won’t have to buy it again in 6 months or a year… and thats the usual story out there in ebikeland for the more demanding users in the DIY world.
Parts (remember oftentimes you can get these chargers for a lot less on clearance on Fleabay). Especially the HLG-185 which is commonly used in street lights):
I had the opportunity to make another charger over the weekend for my daughter and son-in-law. They also live in the EU and as such I needed the appropriate plug – the charger will auto-sense the voltage coming in and adjust accordingly. So for those of you folks outside the U.S., here’s what one looks like.
My daughter’s locale uses a 2-prong grounded ‘Schuko’ type plug. One nice thing about using international parts is they conform to the same international specs. So there is none of the translation necessary to pick which wire goes to where. Just match the colors and you are done.
This time I took the time to take pics before and after during assembly. The heat shrink and adhesive on the marine-grade splice connectors make for a very solid connection. There is a trick to doing the best crimping:
do it on the very ends
don’t crimp so hard you tear deeply into the plastic covering the splice
ensure the pointy prong on your crimper faces AWAY from the other wires so if you do overcrimp and tear into the plastic, you won’t expose metal facing the other wires.
Use a halfway decent crimper. I think I made this point in the original post but it bears repeating. Use the wrong tool for the job and your results will suck.
There is also a trick to heating the adhesive connectors – First, use a nozzle on your heat gun that narrows the heat exhaust so you can better direct it to a small area. Next, heat the ends that you actually need to shrink up and grip the wire. Stay away from directly heating the metal center. If you do that, any tearing of the plastic over the crimp tends to actually seal itself. If you heat the center, those tears will break open further as the adhesive plastic shrinks from the heat. Its actually pretty easy to do… you just have know to do it… and now you do.
Heat shrink over top of those adhesive connectors and you have a stable, solid connection you need to look for to notice.
Do it again for the XT60 ‘universal’ output connector. Make sure that external heatshrink is plenty long. In this case I made sure I had plenty of exposed wire on the end because I like the flexibility. If I wanted to reinforce it and maintain that flexibility, self-adhesive silicone tape (sticks only to itself; spiral wrap it around the wire) is the perfect solution. The Sondors-compatible bottle connector I chose for this charger had a male plug end on it, so I needed to make another connection using a short female-to-female XT60 extension. It is important to get your genders right on a charger. You do NOT want a male XT60 or male anything else exposed on the battery side as an arc between the terminals is much more likely on a male plug, and that can destroy your battery.
Here’s the whole thing put together with a meter added to the end and the Sondors-compatible 5.5mmx2.1mm barrel connector attached. The meter is showing it is configured for an 80% charge on a 52v battery. After I took this pic I realized I needed to set it up for a 48v battery and changed the voltage on the charger and the label on the meter.
These chargers are sturdy enough and water-resistant enough to mount on your bike as an onboard charger. Here is one bolted onto a front rack. The cords are gathered up in a MOLLE dump pouch attached to the handlebar bag. Just open the flap and pull out the cords.