High-level battery overview

Batteries used in your "house" setup have markedly different needs than the battery that's already under the hood of your car. Not that there aren't similarities, but understanding the differences can help you right-size the batteries for your need and avoid battery murder.

At the very high level, there are lead batteries, and lithium batteries.

• Pros
• Less Expensive
• Often simpler to use
• Easily obtainable
• Wide range of existing accessories

• Cons
• Heavy. Like REALLY REALLY heavy
• Easier to murder if they're not treated properly
• Need to be FULLY RECHARGED every day (realistically, this means you need solar)
• Lower useable capacity

While it is possible to use standard automotive batteries that you get at Wal-Mart or the auto parts store as your house batteries, Deep Cycle batteries are better suited to the task. They are designed for more regular/deeper charge and discharge cycles.

• Pros
• Very high energy density
• Light(er than lead)
• Greater usable capacity
• No need to be fully recharged (in fact, they almost prefer not to be)
• Faster charge/discharge ability
• Longer lifespan

• Cons
• Expensive, like REALLY expensive
  • As of 2023, drop-in Lithium batteries have gone from “catastrophically expensive” to simply “very expensive”
• Requires specialized charge controllers
• Cannot be charged when below freezing (Some drop-in lithium batteries come with integrated heaters to allow charging when ambient is below freezing)
• Charge/Discharge voltage different from lead - many “gauges” will not work

With the prices of Lithium coming down to approachable levels, they are becoming more and more popular for all levels of build. There's two methods of obtaining a good lithium battery setup:

• Pre-built or “Drop-in Lithium (LiFePO4)” batteries. These are factory made batteries that you can (mostly) treat like any other battery; they're a sealed black box that already contain a Battery Monitoring System (BMS), safety cut-offs, and sometimes bluetooth monitoring.
• The more industrious (or frugal) can go the DIY Lithium path. This is where you buy the raw cells (usually at a deep discount directly from China), a BMS, cables, and bus bars, and build the battery packs yourself. Done properly, massive capacities can be had for prices so low it's not much more than a good lead battery setup.

For those still pursuing lead chemistries, Deep cycle batteries (Primarily lead) are strongly preferable.