A friend has a nice '54 Pontiac street rod. 389 engine. The car was very recently purchased in finished condition. One day it wouldnt start, battery was dead. Charged battery. Went to reconnect battery and it was the 4th of July. Disconnected the new 1 wire GM alternator, hooked up battery, no sparks. But everytime the 2nd battery terminal was connected a sound like a solenoid closing could be heard. Took the alternator to a service for checking and they said it was great. Told them of the sparking issue and they said that could be expected. Reinstalled alt., hooked up battery, and the 2nd 4th of July. Positve bat. terminal was hot after removal. Can a battery short internally to produce these symptoms? Why would a good alternator have all the indications of an internal short but check out well at an alternator shop? We are going to get it onto some stands and check out the solenoid and other things in a couple days. But help would be appreciated. Thanks
If it is that "hot" of a short it's likely to have a main wire to ground. Check by the exhaust where the pos cable may pass close to it. If all that is good, loosen the starter bolts and make sure the starter isn't locked up in the flywheel. Should hear the bendix release if it was. Sarter solenoid could be the culprit. Ohm out the pos connection to the case on the alt. Should read open. Dennis D
The starter isnt locked up, as he started the engine yesterday with the alternator disconnected. I checked the alternator with a multimeter before it went to the alt repair shop. The meter showed closed. I'll look closely at the solenoid and wiring which may be close to exhaust once we get the car up, as it is TOO low now. Maybe the alternator could be showing proper function without belt tension, but after installed with belt tension it then shorts.
hardly, did the shop spin test the alternator? When you hooked up the power wire on the back of the alternator did the terminal rotate slightly? Either an internal short due to movement of the wires on the inside when you tighten it or one of the diodes is shorted internally. But that is part of testing the alternator. Check the power terminal AFTER you tighten it to see if it is grounded using a ohmeter, with the other end disconnected from power.
Did you charge the battery backwards + to pos ,neg -,also is the battery grounding to frame or innner fender panel.
Apparenyly everything was OK until the battery went dead. Does the output wire of the alt go directly to the battery + or are there connection blocks involved or anything else involved?? If there are other connections to that wire, run another wire, bypassing anything else, from the alt output to the + battery terminal. See what happens when just touching the + battery post. If you get big sparks there is an internal short in the alternator, if not, your short is in one of the other circuits. If you can heat the battery post, it sounds like it is drawing enough current to cause a battery explosion. Be careful!!
Take the positive cable off the alternator, tape it up and connect all of the battery cables to see if you have a short. If you don't have a short without the alternator connected and there is only one wire on the alternator, it has to be the alternator. You will get a slight spark when connecting the cables. Be careful when connecting cables after a battery has just been charged. The hydrogen gas can explode.
I am going to try and get over there tomorrow and get to the problem. With the suggestions it should get done, and I'll make a followup post. Thanks to all.
Found that the battery had reverse polarity, but dont have the explanation of why, how or when that occurred. I took over and installed a different battery and all seemed fine. There may be more underlying issue(s), but they will have to wait until my out of town visitors leave. The owner is buying a replacement battery today. To answer the question, no I didnt charge it backwards, but someone else may have done the deed.
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