# Charging time for 12 V battery

Discussion in 'Electronic Design' started by [email protected], Dec 24, 2012.

1. ### Guest

I have a 12 Volt battery, 9.5 Ah that uses a 12 volt charger 1.0 amp.

Assuming the battery is completely discharged, is there a way to determine how long to charge ?

Thanks,
Andy

2. ### Guest

Power Wheels Charger for Gray 12v Battery 00801-1778

3. ### Phil AllisonGuest

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DO NOT expect others to do the running around for you.

And BTW - this is the WRONG NG for such a question.

..... Phil

4. ### mikeGuest

That number shows up as several different devices.
Don't think you have any choice but to measure what your
charger does.

I think your bigger problem is gonna be sulfation.
The kids are gonna ride it until it stops dead.
The next time you hear about it is next spring
when the battery won't take a charge.

I lost a set of electric scooter batteries because
it got shuffled around in the garage and the power
switch was turned on all winter.

It might also be interesting to compare the calculated time
to charge against the attention span of kids.

Unless you want to pay close attention, you need something
automatic.

Autistic?

6. ### Guest

There's something wrong with the chart for state of charge someone posted. Lead-acid has a negative cell voltage tempco...

7. ### Guest

That's a standard 0.1C trickle charger. C is battery capacity 9.5AH, charging current in amps is 1/10 C, so ideally charge time is C/(0.1C)=10 hrs. Problem is battery does not store all the charge passed through it, so youneed to add about 25%, that gets you about 12 hours. It is one of the bestways to charge because nothing is real critical as far as damaging batterywith overcharge or reducing battery life.

8. ### ehsjrGuest

Yes, with a rule of thumb type approximation:
The amount of charge you put back into the battery needs
to be about 1.2 times as much as you took out of it.

So if you know how much charge your charger puts into
the battery per unit time, divide that into 1.2 times the
amount of charge taken out to get an idea of the total
time needed.

All of that goes out the window with a modern variable rate
charger and/or if you don't know how much charge was taken
out or the rate of charge supplied by the charger or if
the battery has been damaged etc etc.

Ed

9. ### ehsjrGuest

Didn't you post this?

"This might help:
<http://www.modifiedpowerwheels.com/forum/topic.asp?TOPIC_ID=15855>
About 14 hrs and no more, assuming a totally discharged battery."

The chart is there.

Ed

10. ### Uwe HercksenGuest

Hello,

it is not necessary to multiply with 12 V and then to divide with 12 V
again.

9.5 Ah/(1 A * 0,75) = 12,66 h will do.

Bye