diode protection in battery charger circuit?

I am building a charger for large (20-40 AH) lead acid batteries to power kid-size electric cars. I'm using an L200CV voltage regulator that's a step up from the 78XX, or LM317 types. It has 5 pins, and offers more control. Unfortunately, when I hooked it up to a battery in reverse polarity, I fried my L200CV. I decided to add a diode between the negative output and the battery, to avoid doing that dumbness twice. It happened again. How can that be? Shouldn' the diode on ONE output prevent the massive current flowing backwards that I caused? I've now put a 2nd diode on the positive output. NOW I'm safe--right?

Frying in Fresno, Bruce

Reply to
dazed & confused
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I am building a charger for large (20-40 AH) lead acid batteries to power kid-size electric cars. I'm using an L200CV voltage regulator that's a step up from the 78XX, or LM317 types. It has 5 pins, and offers more control. Unfortunately, when I hooked it up to a battery in reverse polarity, I fried my L200CV. I decided to add a diode between the negative output and the battery, to avoid doing that dumbness twice. It happened again. How can that be? Shouldn' the diode on ONE output prevent the massive current flowing backwards that I caused? I've now put a 2nd diode on the positive output. NOW I'm safe--right?

Frying in Fresno, Bruce

Reply to
dazed & confused

It's not clear to me where you put the diode.

If you added it to the L200CV circuit then it should have worked OK. If you added it to the battery then it would not have added any protection.

What diode? What battery voltage?

Mike

Reply to
Mike V

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