okay first of all, my battery goes dead if i leave it hooked up to the car, but if i disconnect it, it keeps a charge. When i start the car cold, the indash gauge reads right around the middle but it jumps up to around 18v when i rev the engine (and the batt light comes on). It seems like once the engine is warm, the batt gauge steadly reads from 16-18v. The lights also get brighter when i rev the car. What do you think it is??
battery goes dead, and reads 18v when running.. help!
- Thread starter 91stang50GT
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DMAN302
My mom says thanks for the pearl necklace.
Might a light be staying on when the ignition is off..maybe a trunk, hatch, glove box, ashtray light..etc be staying on leaving a drain? Could be a bad diode in the alternator..been there done that! had the alt bench tested and yup it was the drain on the battery. Just some tips for you...good luck you will find it.
srothfuss
Last night I stabbed the same guy 7 times in a row
HISSIN50 said:
A Diode is a simple electonic device that prevents the flow of current from a source to ground. It's sort of like a one way door that prevents your battery voltage from being drained. When you have a dead battery and no open circuits in the car, this is always the part that will fix your voltage drain.
dgollem
Dirt-Old 20+Year Member
Had a similar problem, tinkered with it for about a month then got out the old multimeter and started looking for current draw. My problem was the little lights on the vanity mirrors mounted in the sun visors. Never use them and would not normally have looked at them. Problem was the velcro would not hold the cover closed tight enough to hold the switches closed and turn off the lights. I searched the forum and found some good threads on how troubleshoot this problem. Good Luck!
Srothfuss, I am not sure if you were explaining diodes to me. I know what they are, but that was a nice explanation.
Rather than figuring it out indirectly, one can remove the charge cable and see if the draw reading diminishes. If so, that is the problem.
We dont have Advanced here, but AZ here tests for free (not sure if they have them there).
Good luck.
Rather than figuring it out indirectly, one can remove the charge cable and see if the draw reading diminishes. If so, that is the problem.
We dont have Advanced here, but AZ here tests for free (not sure if they have them there).
Good luck.
Maryland Stang
Active Member
srothfuss said:
Diodes in the alternator actually convert the AC current (as in alternating, hence the word alternator) that your alternator makes to the DC current that your car uses. A diode is a simple electronic device (as you stated) that only allows current to flow in one direction. If you look at a diode you will see that it has a colored band on one end. That is the end that current flows out of.
If his car is charging at 18v then the regulator in the alternator has gone bad. The regulators in Ford alternators are cheap and easy to replace. No car should ever charge at more than 14.7v.
srothfuss
Last night I stabbed the same guy 7 times in a row
HISSIN50 said:
Oh no... I was just throwing out a simple explaination for clairification / future search purposes. I knew that you knew what they were... When I was young I figured out the hard way what they do.
Maryland Stang said:
Correct: His alternator is probably shot... I was just trying to explain the purpose of the part with a funny name (Diode).
Maryland Stang
Active Member
srothfuss said:
Actually, it sounds like the alternator is fine. It's the regulator that needs replacing. You need 1 socket and a paperclip to replace it.
Maryland Stang
Active Member
91stang50GT said:
The overcharging may have "cooked" the battery but before you replace it you should test it. There are 3 good ways to test a battery.
1: Aquire a hydrometer from any auto parts store. They're cheap, usually a couple of bucks. To use your hydrometer just put the tube into each cell in the battery and see what the reading is. No cell in the battery should be below 1.225. If there are any cells below 1.225 slow charge the battery for 24 hours. If any cell is still below 1.225 after charging the battery then that cell has failed and the battery must be replaced.
2: Light load test... Turn the headlights on and test the battery voltage. If it is less than 11.5v then charge the battery for 24 hours and test again. If it still can not maintain 11.5v then the battery must be replaced.
3: High load test... Most places that sell batteries can perform this test for you. It can tell you in seconds whether the battery has failed or not.
DO NOT put a new battery in the car until you resolve your overcharging issues.
DMAN302
My mom says thanks for the pearl necklace.
Maryland Stang
Active Member
HISSIN50 said:
Nope, it is easily replaced. It's been a while since I replaced the regulator (3 years) in my alternator so these instructions may be a little rusty. Although there are a few steps to it you basically remove the screws that hold the regulator in and carefully, oh so carefully remove the regulator from the alternator. There are springs in the brushes and if you just yank the regulator out the springs may fly off into another dimension never to be seen again. Then you put the springs into the new regulator, push the brushes back and retain them with a paperclip and install the new regulator. Pull the paperclip and you're done.
The first time you do it may take 10 minutes but you will have actually done a real mechanic's job. You fixed something instead of just replacing it.
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