How long will a charged car battery last for?

Stoke

Depends how badly the battery was flattened and also about luck. My first car hadn't been driven in over a year, and the battery was so drained, the internal clock had stopped operating.

We jumped it off my dads FIAT and took it for a proper thrash to clear some of the crap of the engine after buying it. Never needed to change the battery and never had any starting issues.

forgotmyname

reeac wrote: »

I have a car with an 11 year old battery and another with an 8 year old battery. Neither has ever need charging from an external source.

Park it up for a month or two and come back and post the results.

I have a leisure battery outside. Not been charged for 3 months. Still charged. But stick a small load on that and it would have been dead. Even a flashing LED will eventually draw enough to kill a battery.

Richard53

How long was the car left before they tried to start it? If it was around a month, with all the small current drains that a modern car has even when locked and put away, that would be enough to kill the battery. Also, even if it dosconnected from the car and sitting on a bench, an average battery will lose about 0.5-1% of its charge per day in any case.

Unfortunately, once a starting battery (not a leisure battery) has been completely discharged, it is on Death Row as far as I am concerned. It might last another year; it might fail next week. Putting it on a battery charger overnight will give it the best chance, but you should be shopping for a new one as soon as you can. Winter is hard on batteries for several reasons, and a nice new one for less than £100 is an investment in peace of mind.

Also, if a battery is over five years old, it's pretty much reached the end of its design life, and anything over five years is a bonus.

If you (or anyone) is going to change the battery, make sure you have the radio code before you disconnect it, and check the handbook for any gotchas such as the need to deactivate any alarms beforehand. Some alarms will go off (and give you a hell of a shock) if they detect the battery is disconnected.

goonarmy

So did it run/start?

Lincoln_Imp

Halfords do a free check on battery/alernator/starter motor

My lad has just been and the print out told him the battery was on its last legs so went elsewhere a got a new one

spacey2012

Lincoln_Imp wrote: »

Halfords do a free check on battery/alernator/starter motor

My lad has just been and the print out told him the battery was on its last legs so went elsewhere a got a new one

Surprise Surprise ! ;)

Stoke

To be fair, batteries are pretty cheap nowadays. Like I said, all about pot luck in my opinion. Mine survived the rest of the car despite being fully drained when I bought it. I never used the car to just sit and listen to music, and once the car is running the alternator takes over anyway.

bigjl

A flat battery needs a solid overnight charge to get back to full capacity.

The alternator will not actually fully charge a flat battery which is why some people have flat battery issues time after time

Nothing wrong with charging it for a few hours usijg it then putting it back on charge overnight

I have left my lights on and the battery was completely discharged.

Gave it an overnight charge and the battery was still spot on 2 years later

Lincoln_Imp

spacey2012 wrote: »

Surprise Surprise ! ;)

Not sure what you mean by that ?

Strider590

It's exactly that time of year, where a battery on it's last legs will finally give out.

Every single year, we get the same posts on this forum, people messing about jump starting and recharging for weeks on end until finally they have to get a new battery anyway when the car leaves them stranded away from home.

Get a new battery, it really isn't worth (text removed by MSE Forum Team) about when a new one costs about £50.

On a final note, having personally experienced a car battery explosion (from starting my car after charging a truly dead battery), trust me when I say that after repairing paintwork and removing sulphuric acid from your clothes, you'll wish you'd just got a new one.