You just sold your first-born child into slavery, refinanced your house, and bought a lithium-ion LiFePo4 Battery for yourself. Now you want to know that how to take care of your new purchase: how to charge lithium-ion batteries, how to drain them, and how to get the most life out of your lithium-ion batteries. This will tell you what to do and what not to do.

Prices for lithium-ion batteries are slowly going from being obscenely expensive to only being moderately unaffordable, and sales of this type of battery are steadily going up at SolarCity. Most people use them in RVs, fifth-wheels, campers, and other similar vehicles, but some are putting them in stationary off-grid systems.

Since some people don't seem to understand this: All Lithium-Iron-Phosphate batteries are also lithium-ion batteries, but not all lithium-ion batteries are also Lithium-Iron-Phosphate batteries. The term "lithium-ion battery" refers to any type of battery that moves and stores electrical charge using lithium ions. Lithium ions are used in a lot of different chemistries to do this, and LiFePO4 is one of these.

BMS or Battery Management System

We'll assume the battery has a BMS or Battery Management System since almost all LFP batteries sold as the 12/24/48 Volt pack do. The BMS is in charge of keeping the battery safe. When the battery is low on power or about to be overcharged, the BMS turns it off. The BMS also limits the charge and discharge currents, checks the cell temperature (and stops charging or discharging if necessary), and in most cases. DO NOT BUY a battery without a BMS unless you like living on the edge.

What's written below is what I've learned from reading a lot of Web articles, blog posts, scientific papers, and talking to LFP manufacturers. There is a lot of false information out there, so be careful what you believe. Even though what we write here is not meant to be the final word on LFP batteries, we hope that this article will cut through the cow dung and give you solid advice.

Why use lithium-ion?

In our article about lead-acid batteries, we talked about how leaving them at a partially charged state for too long is their Achilles' heel. It's too easy to ruin an expensive bank of lead-acid batteries in just a few months by leaving them partially charged. That's a big change for LFP! You can leave lithium-ion batteries half charged for as long as you want without hurting them. In fact, LFP likes to sit at a partial charge rather than being completely full or empty. To make the battery last longer, you should cycle it or let it sit at a partial charge.

The lithium-ion battery is almost the holy grail of batteries: With the right charging parameters, you can almost forget there is a battery. It doesn't need any care.