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Battery smoking rotten egg smell

I have a 1989 Honda Prelude with some sort of electrical issue. I keep smoking may batteries. I just got a new one and after a week, it is starting to do what my old battery did: smoking sulfuric gas out when I drive.

Like many of these problems, I only have clues to work from. SO here they are:

  • the battery is dead every morning. Starts up fine all day long. But, totally dead or nearly so every morning.

  • I have blown the battery fuse (fusable link) several times. Oddly enough, the last time, it was when I tried an AM restart. I had parked the car normally the night before after driving 30 miles and in the AM, fusable link was blown.

  • One other possibility. I replaced the alternator about 4 months back. When I ordered the part online, it came with a 4 prong interface plug. My car has a 3 prong interface. The shop was not sure what to do with the 4th wire. They/I assumed it was some sort of signal wire. So it was left hanging and electrical taped off. My alternator light has been on ever since. Since everything worked OK, I asumed that this had to do with the hanging 4th wire. The alternator recharges the batter just fine.



(Yes, a REAL Rocket Scientist)

Have you checked the voltage that your alternator is charging?

This sounds like an overcharging condition, max charge when checked with a voltmeter at the battery should be around 14.5-15 volts.

And you probably have the wrong alternator on there as well. Unless there was a paper in the box explaining the extra wire then you probably got the wrong part.

It sounds to me like the battery is being overcharged. Normal charging voltage should be 13 something to 14 something all depending upon electrical load.

Some alternators use a reference voltage to determine how hard the alternator is going to have to work and if the dangling wire is for that purpose then odds are the alternator is overcharging.
(I’ve got a motorcycle alternator story as a good example of this.)

What should have been done is to use the correct alternator for the car and I would say that a shop that is willing to take on a job like this or send it out the door is best avoided.

I agree. The shop didn’t do you any favors hanging that alternator on and hoping for the best. Get the correct alternator installed and the wiring checked ASAP.You could toast your computer, radio, and dozens of relays and even cause an explosion under the hood from the overcharging that seems apparent.

Well the solution to this problem doesn’t take real rocket science. Like the others have stated, the alternator is bad. Even though the DC output voltage might be in the proper range there could be excessive AC voltage (due to bad diodes in the alternator) coming from the alternator that is killing the battery. Along with replacing the alternator you might need to replace the battery again due to the damage that was done to it. The battery drain problem will likely go away also with the new alternator and the new diodes inside it.

there are two diffferent units for an 89 prelude 1 is for fuel injected cars and the other is for carburatored cars i think you have the wrong unit

If the alternator is an ‘A circuit’ model

the shop likely grounded the field and put the alternator in full field, unregulated charge.