full battery voltage at low temperature -15c

[pickler]

I was wondering what voltage is considered a full charge state for a 12v car battery in cold temperatures? I know for room temperature 12.6v Is considered full charge. But in -16c temperature my voltage is reading 12v flat.

 

[The_Jeff]

http://www.batteryfaq.org/ < SOC table with temp comp there.

 

[GaleHawkins]

12.6+ should be expected based on my experience but the effective cranking amps may be 50% of that stated on the battery label.

It sounds like you need to put a battery charge on for over night perhaps.

 

[pickler]

I trickle charged the battery. Still over night left on the car in -13c temp voltage dropped to 12.2v. In summer time I had no problem hitting 12.6v without charging.

Ya batteryfaq claims 12.5v for -20c temp which is too high IMO. Never seen a car battery do that high after sitting over night in -20c.

 

[Petersubaru]

I have a battery load tester and 2 rather expensive digital multi-testers,..last night the temps dropped to -18C and both my batteries, one having sat 2 nights, each show more then the minimum of 12.5V…my experience with batteries have generally not been good and often I end up taking them back before the full warranty is up…this time I got lucky and decided to buy from Napa (USA)..also on both batteries the rated Amps are much higher then what the sticker reads..one of my vehicles is a diesel and 12.4V is not acceptable to me when the temps can drop even further..The person who sold me the batteries said that 12.5V (at rest) in any weather is considered a good battery as far as volts are concerned...my daughters recently new battery from Ford shows over 12.6V and temps overnight several days ago for that test were -38C (almost the same temp F )…an accurate multitester is crucial since 1/10V either way can skew the facts..

 

[Petersubaru]

Went outside this morning and temps were -14C or 7F…Voltage reading from the diesel is 12.67V and this was confirmed by the load tester that no charging was needed..1007amps available from a 770 rated on the sticker battery..this the 2nd winter of usage...

 

[JDW]

Just replaced the battery in my DD 95 T Bird cranked just fine until temps got down in the teens. Battery was showing 12.6 volts but CCA was down to 250. Replaced working fine now. I have a Optima yellow top in the 96 that's going on 5 years old,I keep it on a trickle charger .