On 8/13/2018 11:31 AM, Bobby Keeland via EV wrote:
Mark Hanson asked "curious if LiFePO4 dies suddenly or gradually like
lead."
The cranking power (specific power, internal resistance) stays
relatively flat over the lifespan, at least in A123's. The capacity
(specific energy) declines slowly of the life span. They "die" when they
don't have the energy needed to crank for sufficient time, which tends
to happen suddenly when you reach that threshold. The battery doesn't
die suddenly, but its capacity is suddenly inadequate. It won't, for
example, crank the extra time needed to start a cold engine.
I built a 4S3P 12 volt battery for my ICE van out of A123 cordless
tool cells. It lasted for about 10 years. Probably would have lasted
longer had I not left it at zero volts for several days a couple of times.
You can check the health (capacity) of the battery by periodically
putting it an RC type cell cycler, like a CellPro:
http://www.usastore.revolectrix.com/Products_2/Cellpro-Multi4_3/Cellpro-Multi4_1089
"Death" will then happen predictably, when you see that capacity
begins to approach whatever it takes to crank and start up your motor.
Bill D.
Does your engine have a pull start, or is it way to large for that?
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