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LiPo Battery Safety

Good morning,

I am currently building a AUV that uses 4 x T100 thrusters, each one powered by their own 14.8V, 4000mAh, 40C, 4S LiPo battery. I am concerned about battery safety during testing, ie, over discharging. I bought a few cheap BMS to connect to each battery; however, I am not sure they are practical for my space-constrained design/waterproof enclosures I have made for the batteries already.

Does anyone have any ideas on how I can prevent over discharge/other unsafe conditions caused by my batteries during operation?

Do the ESCs have any built in safety functions that cut the power link if there is overcurrent, etc that goes through them?

Thank you!


Unfortunately it seems that BLHeli_s doesn’t support low voltage cut off.

Hi @Katie.

If you use something like a BlHeli_32 ESC, you can program in a voltage cutoff, so the ESCs will shut down at the point the battery is discharged to a per-cell voltage you select. You can also set a current limit with many BlHeli_32 ESCs. Many other ESCs other have programmable voltage cutoffs, but unfortunately our Basic ESC does not.

Another easy solution is to plug a low voltage alarm into the balance port of each of your batteries. You can set a lower voltage value, and they will sound a very loud alarm when that threshold is reached.

Just to clarify, over discharging a lithium battery is very unlikely to cause an unsafe condition, the worst that will usually happen is the battery performance will be damaged to the point of being unusable.


@adam Thank you! Those low voltage alarms look promising!


Just make sure you can hear them through the water! If you are not going too far/deep it should work well.