Car battery: Surface charge

_Dragon_

When it comes to the winter i might be needing a new battery, Its done well so cant complain coming up to 11 years. Anyway i know if you check the voltage with a meter you are supposed to drain off the surface charge to get a proper reading, My question how many hours does it take for the excess charge to go after you have stopped the car if you don't use the headlights etc to drain of that charge?

un1eash

Voltage alone won't indicate a dead battery. You need to check charge rate and cranking power.

IronGiant

Best left overnight and test it before starting in the morning.

_Dragon_

I have only needed to check the battery a couple of times i was aware that volt reading can be good but its the CCA that really matters.

I do have a charger i might put that on at the weekend, i will leave it over night then and see what readings i get. Leaving it for 14 hours should be long enough to get a proper reading.

car-man

If after 11 years you are having issues with your battery then replace it!

You can drain the excess charge by switching the headlights on for at least 2 minutes, preferably the heater fan switch on full as well.
A fully charged battery should read at least 12.6 volts and at cranking should read 9.6 to 10 volts.

_Dragon_

I'm not sure if I'm having problems, it took a bit longer to start up the other day but when it was freezing weather it started up fine, if i do have problems i will get another one straight away, how come OEM batteries last alot longer any ideas?  11 years is amazing to new batteries.

Delvey

Diesel or petrol

_Dragon_

Its a Diesel.

Delvey

Strange one. My battery suffers really bad in the cold and takes a while to start my diesel (I'm aware diesels don't really need a battery to start). The starter motor sounds like it's struggling. But I don't use it every day. Do you have a smart car charger? Could be worth trying to charge it overnight if you have.

car-man

I guess the OEM batteries are very good quality.
Make sure you replace a battery with the same spec or higher.

If you didn't have problems in the freezing weather then you should be fine, but I'm sure you will notice if it starts to fail.