Any help on why this might be?

I've been through three alternators (because of bad voltage regulators) since early September when I got this 1988 Prelude Si.

My alternators have also been eating through batteries, which I think I've eaten through four at this point and just had to charge my current one today (got it Dec 23).

 

Well, lets start with what brand are the alts?

 

The one when I got the car was an OE alternator from Honda. The second one was me being cheap: used NAPA alternator ($40). The current one is a brand new NAPA alternator ($152).

 

bad regulators eats batteries (no charge, overcharge, boil away acid via extreme overcharge, etc)
what did they say was wrong with the battery when you took it in to have it checked?

A bad battery can cause the regulator to fail.
over current spikes via shorts or amps/stereo can kill regulators as well.
But mainly wiring problems are the main cause, check battery connections, alternator connections and grounds.

 

Well, I've been going through batteries and alternators.

Here's an idea of what's been swapped or charged since I got the car. It starts less than a week after I got the car.

By that point I might have changed the radio (can't remember when I put in an OE player). There was also an aftermarket alarm on the car when I got it, but whenever I would have these battery issues the alarm would engage which would make it troublesome to start the car for the first time once there was a good battery in it.

09/04/2010 - Duralast battery ($65)
09/30/2010 - Swapped Duralast battery (free)
11/04/2010 - Salvage alternator (NAPA brand) ($40)
00/00/2010 - Swapped Duralast battery (free)
12/23/2010 - New NAPA alternator ($152)
01/24/2011 - Charged Duralast battery (free)

I'll have to check over the connections better. I did recently notice just yesterday that the negative cable was on the battery so loose that it fell right off when I went to use the jump box. The cable end just doesn't clamp that tight anymore I guess.

Thanks for all the help btw. Ive been having this problem on and off for long enough and I've had to explain it so many times that now I don't even know where to begin.

 

I'd replace that end, try to find a nice one where you can solder the cable in. Check the ground between the battery and the body, body and the transmission, check the alternator bracket (make sure it's not painted where the body of the alternator bolts up) Check the positive connection at the alternator, make sure there's no corrosion. I'm sure this is all stuff you mostly already knew, but I just thought i'd throw it out there.

 

Looked under the car and the negative cable isn't looking too hot. Really hoping that's the problem.

Btw, Honda says that cable is discontinued and there's no more left in the country!

 

Make one from a new terminal and some 8ga. cable.

 

I know.

I was just letting people know the OE one is gone.

 

If nothing else it's almost certainly a contributing factor and will probably leave you stranded somewhere.

I'm a little surprised, that's not something i'd expect them to sell many of, I figured there would still be some kicking around a warehouse somewhere.

 

I'm going to investigate it more later (I like the OE look), but one parts guy told me there's none in the country.

I noticed that the terminal end was really lose on the negative terminal (it came off the battery when I removed the jump box a few days ago). Then we looked down below and the cable was all frayed looking and had no casing.

 

with a car that's old enough to drink legally, there's bound to be some parts they stop making for it.
to keep the OE look, I wonder if any other honda part would line up.. or at least be "close enough"...

 

Haha, i'm guessing similar year Accord is probably close.

 

Hmm... Eran drives my old '93 Accord. It's parked outside. BRB

 

So I did the parasitic draw test tonight and it fell around 20 milliamps. Normal for an '88 Prelude Si is 15-25 according to Honda, so I'm safe that way.

Oh, and yesterday I tested my battery to be sure and it read 12.55V.