12v battery

BigGeeking · Scooby Slapper Joined: 07 Jun 2011 Karma :

hi all
just a quick one, hehe

i have a 12v 4amph battery what will be the resting volts?

and what will the

volts be under load if i test when pressing the starter button.?

also when i charge my battery what shoud the volts be immediatly after charging i read about 13.5v then after 1 hr rest it should drop down to 12.7v is this correct.

thanks my bike fixing chums. Mr. Green

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Howling TerrorOutOfOffice · Super Spammer Joined: 05 Dec 2008 Karma :

Have a look here.
https://www.totalmotorcycle.com/maintenance/battery.htm

dolly3900 · Traffic Copper Joined: 12 Jul 2011 Karma :

Hiya,

Your numbers sound about right, 12.5V-12.8V is about right for nominal voltage after standing for a bit.

Charging (from your bike running) should be reading about 13.5V-13.8V and about the same with a charger, although many cheapy chargers will read different as they use a very simply rectified mains voltage, which is OK for charging, but difficult to measure accurately on a standard multimeter.

If your battery is reading below these, then you may have a problem with the battery, possibly a dry or very low cell.
If that is the case and it is not a gel or sealed battery, then you should be able to top up the offending cell with some Sulphuric Acid (get from a motor factors) and as long as the plates are not damaged or twisted, you should be able to resurect the battery.

Failing that, a new battery is not going to cost you too much, just bought one for £20 including VAT and acid.

Hope this helps

Mike

dolly3900 · Traffic Copper Joined: 12 Jul 2011 Karma :

additional........
Just read the link posted in the first reply, pretty much what I was saying

Smile

rustgold · Derestricted Danger Joined: 05 Jul 2011 Karma :

I have to ask, have you had the battery sitting for a long time and have you tried to start the bike from the battery?

I don't get on too often, so in case the answers are yes, a battery that's been sitting will lie about the voltage. Something about particles within the battery forming balls (permanently) depleting the capacity of the battery.
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