Honda Prelude Forum banner
1 - 20 of 34 Posts

·
Registered
Joined
·
263 Posts
Discussion Starter · #1 ·
Ok, I'm finally going to ask some questions. My sons 88si has a problem with the battery going dead every 2 or 3 days. We thought it might be a bad battery so we swapped batteries into my car. If it went dead in my car, we would know it's the battery. NOT.
What would you suggest would be causing it to run down and where would the draw be coming from?
I know the clock and radio clock will not run it down because it's fine in my 89.
What about the Alternator? bad diode letting the battery run down?

Just asking for some suggestions as to where to look. All lights are off, dome light, etc.

thanks for any input.
 

·
Registered
Joined
·
10,750 Posts
So have you swapped your battery on to his car?
Does it go flat as well?
And does your car (with his battery) sit for a few days at a time or is it used daily?
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #3 ·
So have you swapped your battery on to his car?
Does it go flat as well?
And does your car (with his battery) sit for a few days at a time or is it used daily?
Both cars are used everyday.

We swapped his battery into my car to see if it runs down as a way to eliminate the battery. His battery in my car stays charged and the one out of my car that we put into his car ran down last night and would not start his car. He had to re-charge it back up. The alternator is putting out almost 14 volts when running so it's charging but the battery runs down every 2 days. I'm thinking it's alternator problem.
 

·
Registered
Joined
·
10,750 Posts
OK I see, so it's running flat even when using it every day. I wasn't sure if you meant every few days if being left unused.

Have you got a multimeter?
If you can check the current draw with everything off that will tell you if there is a current drain.
Seems as though there is.
Then you need to start eliminating the likely causes.

Although despite that you are getting 14v from the alt it does seem the most likely cause.
You could always swap alternators over and try again.
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #5 ·
OK I see, so it's running flat even when using it every day. I wasn't sure if you meant every few days if being left unused.

Have you got a multimeter?
If you can check the current draw with everything off that will tell you if there is a current drain.
Seems as though there is.
Then you need to start eliminating the likely causes.

Although despite that you are getting 14v from the alt it does seem the most likely cause.
You could always swap alternators over and try again.
Not easy swapping alternators but that's a good way to eliminate it. I would take it down and let the alternator people run a test on it but how am I to know if they are just trying to sell me a new alternator? haha
Thanks and I'll try your suggestion of swapping alternators.
 

·
Careless Cruisin'
Joined
·
894 Posts
Get a multimeter and pull off the positive battery terminal. Put the multimeter on an amperage scale and put one lead on the positive battery post and the other on the positive battery connector to complete the circuit. Note the current that is now passing through the meter. Start pulling fuses and note the change in current draw. Once you see the current draw drop on a particular fuse you pull, you know the problem lies within that specific circuit.
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #7 ·
Get a multimeter and pull off the positive battery terminal. Put the multimeter on an amperage scale and put one lead on the positive battery post and the other on the positive battery connector to complete the circuit. Note the current that is now passing through the meter. Start pulling fuses and note the change in current draw. Once you see the current draw drop on a particular fuse you pull, you know the problem lies within that specific circuit.
I'll give that a try. The clock and the memory in the stereo should not show much doing it that way I dont think. they dont pull hardly anything.
 

·
Registered
Joined
·
15 Posts
I recently had a similar problem. Turned out not to be the alternator. I recommend measuring output @ alternator and input @ main fuse box (wire on right as you're facing car). If there's a significant difference it may be due to a faulty wire in between. I found this out after changing out my alternator. Test lights are simple but wonderful tools.
 

·
Registered
Joined
·
217 Posts
I recently had a similar problem. Turned out not to be the alternator. I recommend measuring output @ alternator and input @ main fuse box (wire on right as you're facing car). If there's a significant difference it may be due to a faulty wire in between. I found this out after changing out my alternator. Test lights are simple but wonderful tools.
hey i wanted to ask u which wire was the faulty one? because i know for sure both my battery and alternator is good...i just have a bad wire somewhere
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #10 ·
I recently had a similar problem. Turned out not to be the alternator. I recommend measuring output @ alternator and input @ main fuse box (wire on right as you're facing car). If there's a significant difference it may be due to a faulty wire in between. I found this out after changing out my alternator. Test lights are simple but wonderful tools.
I know where the black main fuse box is but you said " (wire on right as you're facing car)". Which wire? My son also said he can charge up his battery, drive it to work, come home, let it sit all night and all day and when he goes to work that evening, he has to charge it again so It's going dead in about 24 hours.
He's coming over today and we will try to run tests on it. He has a new battery.
 

·
Premium Member
Joined
·
9,140 Posts
Not easy swapping alternators but that's a good way to eliminate it. I would take it down and let the alternator people run a test on it but how am I to know if they are just trying to sell me a new alternator? haha
Thanks and I'll try your suggestion of swapping alternators.
I think you're being a little paranoid, but if you don't trust the alternator shop, you could try taking it to a couple different parts stores like NAPA or Autozone or whatever you have there. Have them check it while it is running, and tell them you suspect it's the battery. If they both tell you it's the alternator then it probably is the alternator.
 

·
Registered
Joined
·
402 Posts
Both cars are used everyday.

We swapped his battery into my car to see if it runs down as a way to eliminate the battery. His battery in my car stays charged and the one out of my car that we put into his car ran down last night and would not start his car. He had to re-charge it back up. The alternator is putting out almost 14 volts when running so it's charging but the battery runs down every 2 days. I'm thinking it's alternator problem.
Your answer is right here the problem followed the battery not the car. Soooooo the battery is the problem.
 

·
Registered
Joined
·
455 Posts
The way I've always done a quick test is; start the car and remove a battery cable. If the car still runs turn on the headlights and step on the brake pedal, If it is still running, the alternator is fine. At that point it's time to start looking for a voltage draw when the key is off.
Old cars can have odd things like an ignition switch not fully turning off and sometimes a previous owner can modify things that drive you nuts. I had a buddy that wired his stereo amp to his trunk light power and later asked me to help him figure out why his battery kept going dead.
 

·
Premium Member
Joined
·
9,140 Posts
Your answer is right here the problem followed the battery not the car. Soooooo the battery is the problem.
You should probably re-read the original post. The problem is in his son's car. When he put his good battery in his son's car it died, just like his original battery does. The problem did not move with the battery.
 

·
Registered
Joined
·
1,712 Posts
Your answer is right here the problem followed the battery not the car. Soooooo the battery is the problem.
errrrrrrrrrrrrrrrrrrrrrrrr.
^"wrong" buzzer sound.
the battery stayed charged in his car, and his died in his sons car.

rusty, you might wanna replace the battery anyway, cuz i read somewhere that a full discharge shortens the battery life by like 1/4.
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #16 ·
You should probably re-read the original post. The problem is in his son's car. When he put his good battery in his son's car it died, just like his original battery does. The problem did not move with the battery.
That is true. We finally took it to NAPA and they did a check while still on the car. Starting, Charging, diode test etc.

Everything checks out perfect so it's not the alternator or Battery. We cannot figure out where the draw is. We put a voltmeter between the negative post of the battery and the Cable. Pulled all fuses and still shows battery voltage.
Tried it on the positive post with both volts and amps settings. We compared all measurements with my 89 and they're exactly the same as my car. My car does not run the battery down. We are totally puzzled as to what is drawing the battery. The Auto place said "hmmmm, you have a draw somewhere" DUH.....
 

·
Registered
Joined
·
1,063 Posts
We have a chevy truck at work that the brake lights stay on unless you hold up on the brake peddle. I dont know if this helps but you might try moveing stuff around to see if you gat a loose wire somewere. that might why you cant find it.
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #18 · (Edited)
We have a chevy truck at work that the brake lights stay on unless you hold up on the brake peddle. I dont know if this helps but you might try moveing stuff around to see if you gat a loose wire somewere. that might why you cant find it.
we have checked headlights, dome lights, light in the fuse box area, cig lighter, trunk light and everything is Off. This is the weirdest problem I have ever encountered. We pulled every fuse, relay etc and could not make the meter change at all.
 

·
Registered
Joined
·
1,712 Posts
make sure the battery is charged, pull every fuse and let it sit over night or however long it takes for it to die usually.
 

·
Registered
Joined
·
1,063 Posts
Has the last owner put something in the car that you dont know about? It might still be hooked up and you not know it other then that i dont know good luck
 
1 - 20 of 34 Posts
Top