Simple battery charging circuit

[Max_Andrews]

I have a 13.8v, 5 amp power supply, and want to use it to charge a 12V lead acid battery. If I just hook it straight up, will that work? Do I need to put some kind of protection circuit so that it stops when it's full?
Also, what If I want to have the battery charging and the power supply powering a car amplifier at the same time? Diodes?
TIA,
Max

[curt_c]

> I have a 13.8v, 5 amp power supply, and want
> to use it to charge a 12V lead acid battery.
> If I just hook it straight up, will that
> work?

Yes

Do I need to put some kind of
> protection circuit so that it stops when
> it's full?

For a car battery, it should be no problem. The battery will 'float up to 13.8 volts, and the charge current will go down appropriately when it is fully charged.

> Also, what If I want to have the battery
> charging and the power supply powering a car
> amplifier at the same time? Diodes?

Just parallel the amp across the battery. What the amp doesn't require will go to charge the battery. If the amp takes more than 5 amps, the battery will pick up the slack and be slowly discharged. When the amp takes less, the battery will be charged back up.

C

[Max_Andrews]

Sweet, thanks a bunch!

[dthomas]

> Sweet, thanks a bunch!

I agree with whas has been said... but a word of caution if you leave the power supply constantly connected to the battery after it is charged you can overheat the battery and even cause it boil away all the acid(liquid) and if done repeatedly damage the battery. Even a bigger problem if this is a sealed wet cell type battery.

You might consider a timer to stop the charger after a predetermined amount of time.

Dave