Generator overvoltage scenarios

Yes,

LFP nominal cell voltages are 2.5-3.6 V so "12V" is 10-14.4V nominal range

Lead acid nominal 1.8-2.1  so "12V" is 10.8-12.6 V nominal range

LFP max voltage per cell is 4.2 V per cell before damage X 4 = 16.4

Lead acid  max voltage per cell is 2.45 V per cell before damage X 6 = 14.7

16.4 >14.7

this is based on the cell chemistry only....you cook lead acid at 16 volts

There is no thermal runaway in LFP I have short circited them and they do not like it but only minor  smoke no flames just a bulge and a bad battery. I have also used 4 cell LFP on an automotive charge system for four years with NO BMS and no probems. However a BMS is stilll a good idea.

Here's some "minor smoke" for you:

https://www.youtube.com/watch?v=EMARDvMz62A

You really need to learn the difference between a "short circuit" and a "Puncture test".

here is a full comparison

https://www.youtube.com/watch?v=R9xZf4p8PkQ

The point is that LFP chemistry is one of the safest and abuse tolerant...and no acid burns

In what scenario in a light Aircraft will someone hammer a 3 inch nail through your battery ? and if you are worried about that being the thing that kills you when flying then perhaps it is time to take  up shuffle board instead...#stall#spin#midair#fuelstarvation#CFIT

Glenn Martin wrote:

Yes,

LFP nominal cell voltages are 2.5-3.6 V so "12V" is 10-14.4V nominal range

Lead acid nominal 1.8-2.1  so "12V" is 10.8-12.6 V nominal range

LFP max voltage per cell is 4.2 V per cell before damage X 4 = 16.4

Lead acid  max voltage per cell is 2.45 V per cell before damage X 6 = 14.7

16.4 >14.7

this is based on the cell chemistry only....you cook lead acid at 16 volts

There is no thermal runaway in LFP I have short circited them and they do not like it but only minor  smoke no flames just a bulge and a bad battery. I have also used 4 cell LFP on an automotive charge system for four years with NO BMS and no probems. However a BMS is stilll a good idea.

Max voltage per cell means the voltage potential measured between the anode and cathode, not the input voltage used to charge it. They both can be damaged if they are overcharged significantly (tho their failure modes differ), but PbA can withstand overvoltage during charge much better. PbA also can accept overcharge better. The same is true with brief cell reversal (kills LCO and probably LFP but only ages PbA).

It's true that LCO and LFP are the way of the future and that lead acid batteries no longer have a place in modern, light aircraft but I would need to disagree that lead acid is less abuse tolerant to overvoltage. Get an old car with a poorly regulated power source and replace the SLI lead acid battery with any sort of unprotected lithium ion battery and I guarantee you it will not survive without the properly controlled CC/CV charging it needs.

Nevertheless, it does show what is possible, and serves as justification for EarthX requirement to either mount the battery outside the cabin or in a vented container.