drained battery recharge

[dg]

folks, can I recharge drained battery with alternator?
I have a new battery  to jumpstart the car
(found out too late that headlamps were on, so old battery might not be dead yet)
I don't have standalone battery charger, just wondering if it would strain alternator too much

[dg]

ok, that was a bit premature question
apparently it is no good to use alternator for that, it possibly can charge battery but not fully and will have higher strain then it was designed for
thanks to culzean for usefull link on the other topic: http://jgdarden.com/batteryfaq

[culzean]

it says in that article that it may damage the vehicle charging system to try and charge a completely flat battery.  Also interesting to note that they say  'low mileage kills batteries' because the battery is continually kept in a low state of charge.   if you look at the expected battery life chart it shows that battery life is around 30 months in very hot or cold regions of USA and about 50 months in the temperate areas (similar to UK).  Higher daily mileage will look after the battery because it is kept in the top 20% charge - discharge range,  any battery chemistry type has limited number of charge cycles built in, and the more extreme the charge and discharge range the less cycles the battery will survive.

[chrisc]

The initial charge needs to be over 5 amps and this would be sustained for 15-20 mins.  A bench charger with a substantial transformer is needed, as this current will overwhelm most domestically rated chargers which usually provide less than 1 amp.

Your local workshop or battery dealer will have one of these and it is much cheaper trying to resurrect a flat battery than buying a new one.  If the battery is not too old it will recover readily

[dg]

yeah, "written off" old battery already
not worth a hassle to run around local workshops, plus cost of labour is so steep in uk
no point buying proper charger for one off job either

[culzean]

if your battery was more than 3 years old I would definitely get a new one anyway.

[madasafish]

I would be unhappy with battery life under 5 years. My Yaris D4D had its first new one this year for its tenth birthday. Son's Yaris 1.0  is over eleven and on original battery..

[dg]

if battery is used properly/frequently, then yes, should be no problem
plus I suspect original batteries are more expensive/quality items
I don't know how and for how long mine was used before
plus after laying around for few days completely flat it may not be resurrected to full capacity

[VicW]

My battery at seven years old and 50,000 miles was declared suspect today during a car service.

I had it replaced because we are coming to that time of the year when poor batteries fail suddenly and can leave you stranded.

Vic.

[guest4366]

Ours has never ben changed, car a 54 plate, and does very few miles these days. Once a month a put the battery on a bench charger for a few hours to wake it up. The cold has killed so many other units I have in other cars, but at nearly 10 years old the Jazz is still quite lively... Lesson learned for the others I guess.

Dan