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Alternator Caught on Fire

My daughter’s 1998 Volvo V70 had a dead battery. She had a jump start and went to an auto parts store. The battery did not hold a charge and she needed a jump start again. The parts counter person looked under the hood and laughed when he saw a deep cycle RV battery installed. (Two years ago I had put in an spare RV battery and had put it in to replace a bad battery). He said, well that’s the problem. There’s an RV battery in here.This isn’t an RV! He did something, when jump staring again and the alternator caught on fire. The auto parts guy said that it was caused by using an RV battery. Now my daughter is mad at ME after two years from when the battery was put in!

Am I correct in saying that either the car has a short circuit somewhere, the voltage regulator is faulty, or the battery terminals are dirty (possible the ground is not making a good connection), and the reason is NOT because an RV battery was installed?
Should you trust an auto parts counter person to make diagnosis?

Does the parts store clerk have any idea how the RV batteries are charged when they are in an RV? Ask him if he sells an RV alternator. Come to think of it he might explain the difference in AC-DC and RV. That should be quite informative.

He jumped battery at store when he said it was bad? Why didn’t your daughter buy a new battery at store? Battery was dead. It needed a jump. Was she going home with dead battery to contemplate life? Or ask u for new battery?

RV (deep cycle) batteries are designed to be completely discharged and recharged numerous times, whereas an ordinary car battery is damaged by a complete discharge. On the other side, Deep cycle batteries do not have the large “cold cranking” amps that an ordinary car battery does.

But is the RV battery will start your motor, and you don’t encounter very cold temperatures, it should work OK, in my opinion. And in fact, it worked for you for 2 years.

The alternator probably overheated because it was trying to charge a dead battery, which they are not rated to do. This can happen if the battery is either type. Or, there is a short somewhere.

But bottom line, get the alternator and battery replaced, and the wiring checked.

edit: I agree, the parts guy is at fault. He’s a parts guy, not a mechanic.

edit: typo, above should be “But IF the RV battery will start…”

The auto parts guy caused the problem not the RV battery. Give an idiot a good battery and a set of jumper cables and he can burn down the city.

I guess I agree with Bill. The battery shouldn’t have been the problem but would have put a lot more load on the alternator than a regular battery, maybe. I’ve found that when I just pay for the whole thing, all the grumbling goes away though.

A dead battery caused the alternator to overheat and catch fire, deep cell may draw more amps than a regular battery when dead , I do not know, but alternator is fried, most of the counter people I deal with are fairly knowledgeable, but it is possible a regular battery MIGHT not have fried the alternator. Couple of hundred max for a new alternator, do it and call it a belated xmas present, throw in a new battery of course,

did u put meter on system after u jumped car to check system running voltage? They sell $8 meters at harbor freight.

It’s possible the auto parts guy shorted out the alternator by accident, or connected the jumpers up in reverse polarity. When that’s done its hard to predict what will happen, as the circuitry isn’t designed to handle that situation. Usually the main fuses blow is all that happens, but other possibilities include serious damage to the engine computer, the battery explodes, and it appears the alternator can catch on fire. Pretty much anything could catch fire if enough current was forced through a circuit. It’s like making a car into a toaster.

I don’t see any point in tring to figure out exactly what happened there. As posted above, buy a good quality battery and replacement alternator. Cross your fingers the engine computer didn’t get damaged. And secure the services of a good independent auto repair shop for when the car won’t start.

If the battery has completely failed it’s possible the alternator went up in flames because it had to go into full output mode. This can happen whether it’s an RV battery or not.

At this point I can’t fault the parts counter guy.

I tried to jump my kids car. Motor still would not crank. Neighbor came over with jump pack and put positive clamp on remote +aux post on shock tower. Motor cranked fine. Turns out pos post on battery terminal was corroded up. Typical GM battery side terminal issue. Looked fine till u took off post side bolt. Of course all rv battery’s are top post design. Easier to see corrosion issues.

I used to replace the side post bolts on pretty much an annual basis or at least disassemble and clean them up just to insure good contact.