How to maintain Lithium batteries for electric bikes

If you have questions about how to maintain your battery for your electric bike, I have answers. If you're wondering how many cycles you can get out of a lithium battery for an electric  bike. If you want to know what you should do with your e-bike battery and cold temperatures, if you want to know what percentage you should charge your e-bike battery up to. And if you have questions about how to keep your battery properly balanced, and finally, what should you do if you need to store your battery for a prolonged period of time?

How do you maintain your e-bike battery?

Maintaining e-bike batteries is not hard. In fact, in my opinion, they are the easiest. Often when people think about battery maintenance, they're thinking of lead acid batteries, you have liquid that you're having to replace. But lithium batteries are so much easier. Now that  being said, I still want to make sure you get the absolute most you can out of your e-bike battery.

Tip number one is, don't discharge, a lithium battery completely with lead acid that is  okay with nickel metal hydride or nicad, or different other older formats. Some of them actually recommended a full discharge for certain reasons. But with lithium batteries, that is wrong, you do not want to fully discharge the cells to zero. Don't discharge down to zero voltage. That's basically unrecoverable and not good.

Can I ride my e-bike until the battery dies and shuts off?

Now,  does that mean that you can't go for a ride on your e-bike until the battery dies and shuts off?Well, no, it doesn't actually, because every battery has something inside that is called a, BMS.  I feel like this is some sort of mystery device that no one gets to see. You probably know an e-bike battery looks like, but this is just an outer shell or plastic case. And what it looks like on the inside. The BMS also called battery management system. It's basically a smart little circuit  board and you have outputs that are going to the terminals, which would connect to your cradle. There's a little wires going all over the place. BMS is monitoring the voltage of  individual cells. So to put this simply, this battery knows not just when this cell gets down or up to a certain voltage. It also knows when goes to a certain voltage or it's looking at a collection or a group of. The battery management system will  actually cut off the battery when the voltage gets down to a certain point  to prevent your battery from getting damaged. So when you take your e-bike for a ride and you drain the battery until the bars on your display go down to nothing, and at some point the whole bike just shuts off. The voltage on your bike is actually not at zero or anywhere close to it. The cells actually have a fair amount of voltage left, but that's where they need to be cut off for longevity. If you drain them down to zero, like I said, they'd be unrecoverable. Now, do I recommend doing that Kind of running it all the way to the minimum? No, I probably wouldn't do that on a regular basis. But that's what the BMS is for.

How many cycles will an e-bike battery get?

Often a question is how many cycles will they get? And a little  bit of confusion is caused sometimes when I talk about a cycle and what does that actually mean? And basically that is a full discharge and charge cycle. So if you're starting with the  battery at 100% capacity and you drain it down to where that BMS effectively cuts the voltage off. That is a full discharge cycle. But usually somewhere between 800 and 1000 cycles is what these individual cells are rated for. I've seen some people say as low as 500, if you say go ride your bike for 20 miles on a full  discharge cycle, and you could do that. A thousand times that would be 20,000 miles. That's a lot of mileage on an e-bike. If you only get half of that, you know, 500 cycles, then obviously  that's going to be half that still be about 10,000 miles before you wear your e-bike battery out. And I want to be clear that if you go from say a hundred percent down to half of your  battery capacity, instead of draining it all the way to zero, that is effectively only half of a discharge cycle.

What charge percentage should you charge it to?

Now, when we get into charging, this is where there's a lot of interesting information about charge percentages. Most e-bike chargers that come with your electric bike are going to charge to 100% every single time. And that's okay. I don't want anyone to think like they're killing their battery  by charging to 100%. Those cycle ranges I just gave you are normal expectations. If you are charging to a hundred percent, you want the most range you can get out of your battery. If you want to extend the overall life span of your battery, you can charge to slightly less than full capacity and there's good and bad things about that. Let me explain the good first, have you charged to 90%? That's effectively going to be easier on the internal components of those cells. They will actually last longer as instead of 800 cycles, maybe if you go to 90%, you'll get a thousand cycles. Some studies suggest that maybe at 80% charge, you might get double the number of cycles before that battery dies. Personally, I always charge my e-bike to 100%. Do I know that in theory, it might last longer at 90%. Yes, it might, but I know that I'm going to lose 10% range every time if I don't charge it fully. And you know, it's a trade off now. 

How to balance your battery properly?

What is the downside? I think this is something that's often overlooked and that has to do with balancing it's. We're jumping back to that BMS. When the  lowest of the lowest cells goes down to a certain cutoff point, it's going to shut your battery off.And also in the highest gets to a highest point. It's going to turn off the charging function. So it protects the cells from being charged to too high of a voltage and potentially blowing up. We definitely don't that. Most of the BMS is used on the market, require the battery to be at 100% to balance the cells. And what they're doing is basically allowing each cell to be charged up to a certain point and then stop. If you don't charge to a hundred percent, some of those are not capable of balancing the cells. Some will get lower, some will get higher, and your battery is not going to perform as well and may die prematurely. You may not get as much range out of it. So even if you do  charge to 80 or 90% increase the overall life expectancy, it's a good idea to still  charge to a hundred percent on occasion to make sure that the cells are balanced.

What is the best percent of charge to store your battery when not in use?

Now, what about storage? And I'm not talking about putting your batteries on a shelf. And  where do you physically put them? What is the best percent of charge or voltage to store your battery. Different voltages will actually cause different things to happen within the battery. Typically most batteries will slowly drain or lose voltage over time. So you really do not want to leave your battery dead for weeks or month, you may go plug your battery in and nothing happens. It doesn't want to charge  because the cells have gradually dipped below the lowest safe voltage to charge. The BMS is not going to allow those cells to charge, your battery is toast. Now, if it's going to be a few days, maybe even a few weeks charging to a hundred percent and leaving the battery that way is just fine. Let's say you live in an area where it's snows heavily in the winter, and you don't feel like riding out in the cold. And you know, you're not going to ride for two or three months, the best storage number that I've  seen based on lithium ion cell studies shows to be around 70%. You could charge the battery up to around that 70%. You could look at the voltage on your display or some other number to kind of gauge, if you might be in that ballpark. Or you could charge your battery up to a hundred percent, go for a five mile ride around the neighborhood to bring it down a little bit.

Do batteries like being out in the elements?

Do batteries like being left out in the cold? The answer to that would be no. If you leave your e-bike outside or in the garage, and the temperature is freezing or below, do not charge your battery. They really don't like it. And unfortunately you can cause permanent damage. It's better to take your battery inside, let it warm up to room temperature, and it will be much happier. For just charging, that's a little bit different, it's okay to start with your battery at room temperature, take your bike from inside and go on a cold ride outside. What you may notice if it's really cold is a loss in performance. Meaning your battery won't produce quite as much power. The bike might feel a little sluggish. It may not have the same amount of range. If you know you're going to be out for a while, I would recommend it insulating the battery in some way. I've seen people design custom sleeves that go around them, I've seen people put their batteries in a triangle bag in the frame. Anything you  can do to keep it a little bit warmer in freezing temperatures is only going  to help not only the performance, but also the overall longevity of the battery.

These are some frequently asked questions about battery maintenance for electric bikes, I don't know if they are helpful to you. If you have any other questions about e-bike batteries, feel free to leave them in the comments below!