Thread: battery voltage

What should the battery voltage be across battery terminals when the car is off? I just checked mine today and it came up 12.10v, which seems low, but it is only10 degrees out... was just reading that at 100% charge it should be around 12.66v..

Time to put a charger on it and charge it before the cold takes it all the way out? the battery is only 2yrs old, just a standard autocraft 700 CCA battery


Only checked this because I got a "charging system failure" message on the DIC the other day... but it hasn't came back and when running the battery voltage on the DIC says 13.9 to 14.5v when driving

Sounds fine to me. I'd check and make sure all the cables and terminals are clean of corrosion and tight since you got the charging system failure message.

my old battery corroded severely and leaked acid, cleaned that up and neutralized it back then but maybe I didn't get it as good as I should of? duno... been zero or below here a lot the past few weeks so haven't had much time to look at it. terminals right now seem clean. where's the chassis ground at on a 2008 GP? need to check that also

no it happened while driving, and disappeared in a few minutes on its own so I never got a chance, but the DIC said at the time the battery voltage was 14.25 volts when it went away

Originally Posted by bluebsh

my old battery corroded severely and leaked acid, cleaned that up and neutralized it back then but maybe I didn't get it as good as I should of? duno... been zero or below here a lot the past few weeks so haven't had much time to look at it. terminals right now seem clean. where's the chassis ground at on a 2008 GP? need to check that also

Check the grounds where they bolt to the transmission.

all the terminals and wire hooks that connect to them seem clean..

just started up my car and it went from 12.10v to 13.5v to 14.1v then to 15.1v within 1 minute of running, 15.1 volts seems a bit high with nothing on but the engine running

I'm not sure about nowadays, but in the "old days" (I can't believe I'm saying that) a voltage regulator would control to a higher voltage when cold. 15.1 would have been considered normal on some cars when cold, and dropped to 14.5-14.8 when hot.

This was inherent to the design of the components, and could have been designed differently, but it worked out well (to charge the battery faster after the engine was started) so they left it alone.

I've seen a Maxima which charged at 15.5V and this was considered normal.

I'm not sure if the newer alternators also have a higher voltage when cold.

-BC