June 07, 2021

It's been nearly a decade since I wrote my first charger related blog post, which is titled, 'Battery Tender for a Lithium Battery'. In that post, I explained some very basic concepts about the difference between lithium and lead acid batteries, and explained why the chargers for these need to be different.
In the decade since, we have seen every conceivable piece of misinformation about the proper charging of lithium batteries.
I have to say- people have found and repeated some very...interesting information over the years, and this is a good time to update that post and hopefully clear up some of the bad information that is out there.
Technology and materials have improved since 2012, while the cost of batteries has come way down. Properly charging your lithium battery is easier than ever.

Let's start with this premise: any and all lithium batteries used in the powersports and motorsports markets use 'Lithium Iron Phosphate' cells- also called 'LFP'. These are 3.2v per cell, and are used in these applications because they are safe, powerful, and readily available.
There are no 'LiPo' or 'Lithium Polymer' based batteries used in these markets, because these cells are much more 'volatile' (dangerous). These 'LiPo' cells are 3.7v per cell. This is important to understand, because we often see these terms interchanged as though they are similar. While they are both 'lithium cells' that is where the similarities end. Please- stop calling them 'LiPo'.

With that in mind, let's dispel the first piece of bad information about charging:

Hobby and RC Chargers:
1. You should not use a charger for your RC car on our batteries. RC hobby chargers are 'balance chargers'- meaning that they use a special plug to connect directly to a cell pack, in order to 'balance' the charge between cells.
1a. Our batteries have a circuit board inside that handles the balance function, so a balance charger is not needed, required, or wanted.
1b. Our batteries do not have a balance port that would allow you to connect an RC hobby charger.

Occasionally we are asked if our batteries are '4S' or '5S'. We offer both, since we have 13.2v and 16.4v batteries, but again, the only reason why that would matter is if you are trying to use a balance charger on our batteries. Since there is no way to do that, it doesnt really matter. Years ago, I wrote a post called, 'Balance Charger or BMS for Lightweight Lithium Battery' which explains this in more detail.

Powersports 'Lithium Compatible' Chargers:
2. You should always use a charger specifically designed to safely charge 'LFP' batteries. We sell Optimate chargers exclusively, because we have found that they do a better job of safely and quickly charging our batteries than any other charger on the market.
2a. Just because a charger says, 'Lithium Compatible' on the sticker does not mean it does a good job of charging. In our testing, we have basically found that only the Optimate and CTEK did a good job of charging 'LFP' batteries.
2b. In case that last point isnt clear, I would strongly suggest that you *NOT* use chargers from other companies. Even if you dont buy your charger from us- this is still true.

Hi Amp or 'Rapid Chargers':
3. A high amp charger is not always better. In fact, it is often worse to use a high amp charger on a lithium battery. We see this a lot with car chargers that are '25a' or similar. Here is the reason-
Generally, you use a charger when you have drained the battery. Often, the charger gets used in a 'oh shit' moment, when you hear the call over the PA system to get to the lanes, and you realize you didnt charge the battery.
So, you naturally think that 'more is better', so you blast the drained battery with 20-25 amps.
The problem with this is the voltage- these '25a' chargers are dummy chargers that are going to supply 25 amps at the max charge voltage.
That is really bad.
That will kill a battery very quickly.
Bad things will happen to your battery if you do this.
Really. I promise.

A good charger- like the Optimate- will measure the voltage and 'state of charge', and will feed the battery the appropriate current and voltage to safely and quickly bring the battery back. In our testing, the 9.5 amp Optimate will charge a battery faster than a 25 amp dummy charger, because Optimate created a solid charge profile.

If you avoid this advice you will damage your new expensive battery, and it will not be fixed or replaced under warranty.

Here is what I hope you all take from this post: it is crucially important to use a quality charger on your lithium battery. We have spent years studying and testing every possible charger we could find, and we have come to the data driven conclusion that the Optimate chargers that we recommend simply work better than anything else available.
If you have an old charger from your RC days, or purchased another brand of charger from your dealer- understand that your charger is simply inferior to these. As you can tell from reading my blog posts over the last decade, technology has improved, and this is now the best available.
Choose wisely.