How long does it take to charge a battery?

I’ve had a friends bike battery on charge since 3PM yesterday afternoon and its still not charged. Is that normal?

Its one of those chargers that will charge to full and then maintain.
The “Charging” light is on and the “Maintainence” light hasn’t come on.

How long does it take to charge a battery to full?

Depends on the current your charger uses and how it does it (the program.) Whats the charger?

With an Optimate 4 with a not compeltely flat battery I would expect it to have completed by now. But it can take over 12h on a severely discharged battery or if it has to do other stuff like de-sulfate.

If the battery does not come up to specified voltage it may be buggered, but I expect your charger to have a test cycle that should detect this however.

It’s one of these (halfords own brand charger)

Its set to bike mode which is 1.5A

It was very discharged but I dont know it it was fully discharged. 12hrs would make it 3AM but its noon now and its not done.

my battery (8.6Ah) would be fully charged from empty in under 6 hours on that charger.

My guess is that the charger is not detecting the voltage coming up above 12V (13.6V?) so it doesnt think the battery is charged in order to go into maintenance mode. Doesnt seem to have a test function.

Try disconnecting that battery and testing the voltage. My guess is battery is on its way out…

Optimate is pretty good at working this stuff out and telling you if you can get one to try. Alt take it to a garage to test it.

i’d say the battery is fooked.

get a volt meter on the battery see wot it says.

^^ lol thanks chopr - man of few words :smiley:

Took the bosch battery for the cbr two goes to charge up on the older version of that charger.

Is there not some check you can do with a multimeter to see if its fked or not?

yes! bung a volt meter across it if its not showing steady over 12V its fooked!


yup, it’s shagged. I had one do that exact thing and it failed on a ride

takes fukin ages in your case

He took it home, stuck it on the bike and it wouldnt start. Its fooked =P

well depends if the charger in working right as well normaly leave it on for 24 hrs in a vented place also if its not a sealed battery have you checked the cells to see if there topped up plus leave the top of the battery if an unsealed one as it could blow up if yr face. if the cells are dry or low it wont charge. to top it up just boil some water in a kettle let it cool and use that to top it up

an optimate does take longer than a charger

With the ignition switched off the battery voltage should be greater than 12.2v.

If the voltage is below 12.2v then recharge the battery.

You can calculate the number of hours to fully charge a flat battery by dividing the battery’s Amp hour rating by the chargers Amp rating and adding10%. For example to fully charge a completely flat 10Ah battery using a 1.2Abattery charger will take (10/1.2=8.3+10%) = approximately 9 hours.