Solid state charger

Hi, I am working on a project using a solid state charger to charge a battery, but it breaks down with the battery load and won't put out. It works fine off the battery. This is a 12v system and the chargers are 1amp chargers. I have one type that works, but a couple of different ones that won't. Do I need a load resistor to fool the charging circuit? The batteries are only pulled down to 7.2 volts, but they won't work on a new battery either. What do I need to do? Thank you, TC

Reply to
Inovation
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What type of batteries? Are the chargers meant for charging these?

Tam

Reply to
Tam/WB2TT

Some battery chargers "fold back" when they source too high a current. Weird that the charger doesn't charge a new battery. Are you sure the new batteries aren't dead?

Send more info on batteries and chargers.

Reply to
EdV

Yes, these are new batteries. They are Rechargable sealed lead-Acid

18Ah batteries. One of the chargers is a DVE switching adapter Model DSA 30w Output 12v 2amp. Thanks
Reply to
Inovation

Can I externally use a resistor to keep the charger from " folding back?"

Reply to
Inovation

First problem. The charging voltage for a 12v lead acid cell, needs to be well above 12v. It'll depend on the actual cell structure of the battery, but typically 13.8v. A 12v supply, will _not_ charge a '12v' battery. Second problem. Your batteries are hellishly over discharged, if they are 'pulled down to 7.2v'. Normally discharge should not go below about 10v, or you risk destroying the cells. You need a voltage regulated supply, able to deliver 13.8v (check with the battery manufacturer for the right figure), which is then current limited to deliver the required charging current. Ideally, the system should have a two stage voltage level, turning up the voltage if the cell is bdly discharged, and then turing it down when the battery approaches full charge (to avoid overcharging the battery). Several manufacturers do control IC's designed to implement such a charger, but you are looking at something _much_ more complex than what it sounds like you have...

Best Wishes

Reply to
Roger Hamlett

Try a 10 Ohm 10 W resistor in series with the charger. That should prevent foldback. The charger should be putting out at least 14 V on its end. If the battery is down to 7.2V, its gone, like somebody said.

Tam

Reply to
Tam/WB2TT

True but the OP did say it was a 12V charger (not PS) and as long as it's meant for lead acid and not some other chemistry then a 12V charger will provide an appropriate output voltage. However sealed lead acids require slightly different charging than flooded.

Now there's a possible problem. A good charger will refuse to start if the battery voltage is too low. Amoung other things to keep from charging a 6V battery with a 12V charger and 7.2V sounds more like a 6V battery than a 12V battery.

Robert

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Reply to
Robert Adsett

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