How to ruin your batteries, amputate your fingers, and burn down your home

aka “Safety Warnings”.

If after reading this you disagree with anything we said, please cancel your order.

First, the good news. LiFePo4 batteries are one of the safest types available. They contain no hazardous or noxious substances, and have superior thermal and chemical stability compared to other lithium battery chemistries. That said…

The battery cells we sell will store A LOT of energy (that is the whole point) – more than enough to maim and/or kill you, your friends and family, and burn down your house, RV, boat or whatever, if you do not know what you are doing.

Here is a short list of ways to screw up. This list is not complete.

  1. Take off all metal jewelry (rings, watches, chains).
    • When they bridge the battery terminals, your jewelry will instantly weld to the battery, get red hot and burn off your fingers, wrists, et cetera.
    • Search for “burn-induced compartment syndrome”. Not fun.
  2. Do not connect equipment in a way that bypasses the BMS.
    • This is one of the most common mistakes. ONLY the BMS connects to the negative cell terminal.
    • C- on the BMS is your negative battery terminal, regardless of what the instructions for other equipment may imply.
  3. Use a voltmeter to check the polarity of your cells!
    • We have seen cells with the labels on backwards. Check it yourself. Reverse polarity will destroy the BMS and start a fire.
  4. AC inverters can electrocute you just like regular house wiring.
  5. De-energize your AC systems when working on them or you could get electrocuted and die
    • (If you don’t know this already you have no business using anything we sell).
  6. If you wire the batteries in any one of many wrong ways, they could be destroyed and/or burn down your home.
  7. Even the cells by themselves, depending on how you wire them, can produce enough voltage to kill you.
    • A 16 cell 48v battery can electrocute you in the right circumstances.
    • Overkill Solar LLC does not advise or support any DC systems in excess of 48v nominal design voltage.
  8. Using cheap inverters or other low-quality equipment can damage the BMS in a way that will not be apparent until the batteries explode.
    • This actually happened in our lab- high voltage spikes feeding back from a very large, very cheap inverter ruined the BMS.
  9. Programming your BMS incorrectly can lead to a variety of disasters.
  10. Pinching a balance wire will cause a short circuit that melts the wires, and might damage your cells or BMS. Pay attention when tightening the terminals.
  11. Dropping tools between two terminals will short circuit the batteries and lead to a variety of disasters. 
  12. Using our BMS with unsupported battery types could lead to fires.
    • We guarantee our BMSs work with new grade-A LiFePO4 cells unless otherwise specified.
    • If you use mysterious cheap cells you found in the dark alleys of the internet, the results are not our fault.
  13. If you run your batteries in the sun, or in a sauna, or over a wood-burning stove, they may overheat and be ruined.
    • Operate them within their specified temperature range.
  14. Do not undersize your wiring for the loads in your system, or omit properly-sized circuit-breakers. If you do, the wires can melt and burn down your house-boat-shed-camper.
  15. If you are using lithium ion cells (example: Recycled Tesla Modules), EXTREME care must be taken when making connections.
    • This type of cell will burn and explode vigorously if damaged.
    • We recommend installing Lithium-ion batteries in a detached structure like a garage or shed, not inside a dwelling.
    • If a fire starts while working, retreat to a safe distance and call emergency services.
  16. Do not let the batteries or BMS get wet.
  17. Pay attention to your metal tools when working near the battery terminals.
  18. Do not work on electrical systems while drunk, high, stoned, or otherwise intoxicated.

The bottom line is, the only thing we guarantee is that the products we sell will be high quality and free of material defects. If they turn out not to be, we will replace them. We will not replace connected equipment, your house-boat-shed-camper, or anything else that we did not directly provide to you.

Unless specified, these products have not been evaluated by a Nationally Recognized Testing Laboratory, ie. UL. It is up to you to determine whether they are fit for your particular project, and what regulations apply to that use.

Whatever stupid thing you do with our products after you buy them is 100% on you. There is no way to make them completely safe. 

We support you learning new things through research and experimentation, but a certain baseline level of technical competence and sound judgement is absolutely required.

This page was last updated on July 14 2023