temperature influence on state of charge

[Lee72]

Hello members,

I am not clear about temperature influence on state of charge for SLA batteries. I have found several tables in the web that state the opposite. Here are 2 question:

1. I have a battery with 100% SOC at 80F, voltmeter = 12.7V. If i now put the battery in a warmer place (100F) will it read more, lets say 12.75V ?
2. Chargers compensate for temp, my Mornigstar does -28mv/C meaning lower voltage with higher temperature. why is lowering the voltage?

Thanks in advance
Markus

[Sunking]

Mark temperature compensation is inverse coeeficient meaning as temps go up, voltage comes down. SOC voltages on a working system are pretty much useless.

[PNjunction]

With my various sla's, I've never really noticed them raising in voltage when the ambient temperature was raised. They will however have a faster rate of self-discharge as the temps rise.

Normally the manufacturers charts center around 68-78F, and the compensation up or down begins from there when charging.

Good quality products do temperature-compensation, usually ambient at least, and the best incorporate a temperature probe to get as accurate as possible with actual battery temps - which also help guard against thermal runaway. Note that batteries take a bit of time to release or absorb heat - a quick change in ambient temperature may not be noticed by the battery right away, so the probes are the best bet - but ambient is better than nothing.