9 replies to this topic

[MiniSi]

Any idea how long, on "Normal" speed, it takes to charge a car battery?

Thanks

[minidaves]

yep i have one it depends how flat it is

dave

[MiniSi]

I'm not totally sure Dave. When I connected it up the lights on the dash were quite faint.

I'm going to see how it is tomorrow morning

[Modmobile]

We've got one, dunno if it's Halfords though. It was usually okay if we left it on charge overnight (Rover with dicky alternator )

[minilady]

Does your charger have a meter to tell you how much current it is putting out?

If battery is rated at 35 ampere-hours, it should theoretically deliver power for at least 35 hours at 1 amp, 17.5 hours at 2 amps, 7 hours at 5 amps etc.

Charging is less efficient, so a cmpletely flat battery would take more than 35 hours at one amp to fully charge it. But if your battery is capable of lighting a lamp, it's not completely flat, and you can use (amp-hour rating divided by charging current) to estimate charge time.

With most chargers, the current drops as the battery charges.

If charger has no meter, I'd guess it delivers up to 5 amps into a flat battery, dropping to 1 or 2 amps after an hour or so, then down to 1 amp or less as the battery reaches full charge.

If you have a voltmeter, a fully charged battery should read around 14 volts with the charger switched off. Or you could look for the gassing and temperature rise that happens at the end of charge.

[gsms]

I just leave mine on over night and its fine by the morning.

Si, if yours isnt working I can pop mine round today/tomorrow?

Guy.

[MiniSi]

mines f**ked mate for want of a better explanation. lol.

[Bounce]

If your battery is comnpletely flat, check the electrolite levels, If its a sealed battery dont worry about them. If your electrolite levels are low you can refil them with lightly salted water, fill it you so it covers all the plates inside.

But i'd highly recomend buying a new battery, it will hold its charge longer than a battery that has been fully discharged.

[MiniSi]

Hi bounce. Thanks for your helpful advice in this and the other thread of mine. With regard to the battery its brand new and I flattened it in the old car. I've left it on charge and its going ok so will see how it goes

[Bounce]

No worries buddy