Car battery chargers

Reply to
Mike Walsh
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Hi

I have a power supply which says on it:

Regulated power supply - Input: 110V-220V - Output: 9V/12V DC @ 1A

Is this power supply can be used to charge 12V car batteries and How long does it take to full charge a 12v battery?

Thanks in advance

Jif

Reply to
Jif

It will probably make a good emergency charger. Charge for one day. A car battery is about 12.6 volts. I made a charger out of a spare computer power supply. It works very well.

Reply to
Paul

If it's well regulated to 12V, then no.. Your battery will never be fully charged. You will need something that puts out more than 12.6 volts to charge a car battery. You should check the output of the power supply and see how accurate it is. If it's 13V or more, that should be sufficient though at 1A, you'll be waiting a while if the battery is completely drained. If it's just low, it could take just 15 minutes to have enough juice to start the car but I'd give it about an hour at least so you don't risk burning up your alternator.

-Bruce

Reply to
Bruce Chang

Paul

I have some extra PC power supplies.

pls can you email me a diagram and part list to build one

my email is **** snipped-for-privacy@uk2.net pls remove stars **** tia

jif

Reply to
Jif

Your power supply is useless for charging a 12V car battery. You want a no-load voltage of about 15V if possible. If you had two of these you could hook them in series and carefully use it as a charger. You would want to monitor the charging voltage, which I bet would drop down under 16V under load. You might also take the power supply apart and remove the "regulator" so to speak. Check the basic transformer AC output voltage. You might be pleased to find that it puts out 15V or so. Then hook the rectifier back to it and use it without the old regulator. Make sure whatever you do is fused.

Reply to
MaxAluminum

A car battery consists of six 2.2V cells, for a total voltage of 13.2V, no load.

Most car chargers put out at least 14V. A regulated 1A power supply would not work because the car battery would be such a heavy load when fully discharged that the regulator would shut down.

Reply to
Steven M. Scharf

I bet that the "Regulated power supply - Input: 110V-220V - Output: 9V/12V DC @ 1A" will burn out in less than 5 minutes. A discharged car battery is huge compared to that power supply, looks like a short circuit to the PS.

Bye, Leon

Reply to
Leon

Not sure if you actually need to charge batteries or if this is more of an academic question, but if it's the former Harbor Freight has a 6 amp battery charger for 20 bucks. I have a small 4 amp charger I use on occasion, it takes 8-10 hours to charge a battery. The 6 amp would be somewhat faster. You can buy a 100 amp charger which will also start a car for about $75. I also like building stuff, but sometimes what you can get off the shelf is so cheap these days it just doesn't make sense.

Dan

Reply to
Dan

The battery will try to accept all the amps you can feed it. Unfortunately, that would destroy the battery. For that reason charging amps are regulated. Trickle chargers typically work at around one amp or so.

Reply to
Pyats

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Reply to
Pyats

Wouldn't that be in parallel? Series would give you a no-load voltage of 30 volts and double the current through each power supply.

Even if the power supply was only 13V and the battery loaded it down to 6 volts and supplied 1A, the battery is still charging. The voltage will slowly creep up and reach 13V. Once it reaches 13V, you're looking for a drop in current until the current is minimized. At 13 volts and 1 amp, it may never drop.

Painfully slow? Yes. Useless? No..

-Bruce

Reply to
Bruce Chang

What is the REAL (measured) output voltage out of the thing?

If its a true 12.0 volts, it won't charge a battery at all. You have to push above 13 volts to get a car battery to begin charging.

Reply to
Steve

The power supply in question can only supply 1 amp max, then burns out.

The regulated part on that power supply is voltage, not charging amps. It is not a battery charger.

The only reason the power supply will not burn out (other than some internal protection) is that the regulated output voltage of 12V is too low and will not charge the battery (already mentioned).

Bye, Leon

Reply to
Leon

Yes. I meant a real battery charger.

It has worked very well for me on a number of occasions. A computer power supply puts out around 10-20 amps at 12v. Obviously, don't leave it on and fry your battery. (I tend to leave the interior lights on all night sometimes.)

12v is enough to start my car and 1 1/2 hours on my battery is enough.
Reply to
« Paul »

I just checked the one I use and it puts out 13.01 vdc with a

194 light bulb as a load. No load and it turns off. I don't know if that is normal or not.
Reply to
« Paul »

I had to charge up my neighbor's battery quickly yesterday so I hooked four chargers to it at the same time, a 15A, 10A, 6A and a 3A. In two hours it was tapered off pretty good. You can make up for quality with quantity in this case.

Reply to
MaxAluminum

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