Table of Contents

12V batteries and battery boxes

see also:

  • I don't sell any of these nor do I receive any remuneration if you buy them, and I have not personally reviewed all of them, they are listed here to give you perspective
  • this page gives details and examples of deep cycle batteries which allow greater capacity to be used BUT they cannot be used to jump start your vehicle - see lithium jump start batteries and other jump starters for this use
  • new battery technologies are likely to come by 2027-2030 which will be much better than lithium so don't invest too much money
  • you cannot charge these up at electric vehicle charging stations!
    • you might be able to charge these from your EV with a 240V adapter and your usual 240V AC charger
  • most of these are NOT designed to be used in the engine bay - it is too hot there!
  • if mounting them under your vehicle make sure they are protected from puncture and they are fully waterproof - see https://www.youtube.com/watch?v=KkK0hEDKNzs

Introduction

Summary recommendations

Physical size considerations

12V battery sizes

  • interiors of vehicles get HOT on sunny days - this may severely impact the life span of the battery if exposed to long periods over 40degC
    • LiFePO4 batteries last much longer if kept below 30degC
    • even an August winter day in Melbourne will give around 30degC in the boot of a Subaru under the hide

Types of lithium batteries

  • many lithium batteries risk explosion if they are short-circuited (ie. the positive and negative terminals touch each other via a conducting object)
    • ensure the terminals are protected from accidental metal contact
    • always use a fuse on the positive cable connected to the battery
    • don't carry smaller batteries such as power tool batteries in your pocket with your car keys!
    • this is much less likely in 12V LiFePO4 batteries as they have the added protection of a built in BMS  which protects and shuts the battery down in the event of Short Circuit, Over charging, Low discharge, Over and under Temperature

Li-ion polymer batteries

lithium NCM batteries (Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) )

standard LiFePO4

high density LiFePO4 batteries

new LiFePO4 solid state batteries

Battery specifications

  • if you want to use an AC inverter with a battery to run a 1200-2000W AC appliance you will need a higher capacity battery with higher continuous discharge rate
    • 1280W = 100A current from your battery and this can drop your battery voltage below its cutoff voltage and this will then result in sudden loss of power
    • if running such high wattage devices, you probably should consider a caravan style 200 or 300Ah LiFePO4 battery but it won't fit in a standard battery box

Joining batteries together

240V AC-DC chargers for 12V LiFePO4 batteries

  • recommended charging current for LiFePO4 batteries is typically 0.2C to 0.5C (20A to 50A for a 100Ah battery), but charging at lower currents is not harmful—just slower and may be more gentle on the cells - in general, aim for a 25A charger unless you have a 200Ah or bigger battery

12V 40-50A chargers

12V 20-30A chargers

12V 15A chargers

Battery boxes and Power Stations

no battery box, use a power box instead

Battery boxes

general characterististics

examples of battery boxes with AC inverters

examples of battery boxes without inverters:

Power stations

wall mounted Control Hubs

12V LiFePO4 deep cycle batteries

pros and cons of LiFePO4 batteries

  • there are many “cheap” LiFePO4 batteries on the market including some listed below - these may or may not have quality undamaged cells, quality build, or properly balanced cells and may have lower capacity than specified, shorter life spans and have specific requirements regarding charging, etc - do your research!
  • some cheap budget end batteries claim 2000 cycles but this is at only 30% DOD in which case you may find there are under 1000 cycles for 80% DOD whereas better batteries may claim 4000 cycles at 80% DOD! You are probably getting better value in the long term from the 4000 cycle battery even if it is twice the price!
  • reputable manufacturers include:

models able to fit on floor of rear seats of cars

compact, light 2.5-5kg 15-40Ah models

relatively small 6-8kg 50-55Ah models

100-130Ah slimline models

10-14kg 100-140Ah similar size to standard lead acid batteries

140-200Ah 12V LiFePO4 batteries

300Ah 12V LiFePO4 batteries

with car jump starting capability as well

Lead acid batteries

characteristics