When the car is driven for a bit, the voltage drops way down to the point where it won't start.. but if I leave it for a while, the car will start back up again.
I have an 84 camaro.. With an Edelbrock Carb and intake.. no emmissions. I also have a vacuum advance distributor.. so the electronics have pretty much been eliminated. I changed the starter, alternator, battery, and have an external syllenoid for the starter. I just had the alternator and batter checked yesterday, they were perfect, but they told me that the battery voltage WAS low. Something underneath the dashboard is clicking like crazy. Is there something under the dash that controls charging??
I have the power coming out of the back of the alternator going straight to the batter, and to the battery connector on top of the alternator. The other connector wire is going to the voltage gauge. What could be wrong?? Also, the battery cables are NEW. I think the problem might be something to do with that syllenoid clicking under the dash. I believe that it has something to do with charging.. but I am not sure. If anyone could explain the charging system to me, I might be able to figure it out....

Thanks,
John

 

I had a problem simiar to that in my 81 trans am. When I would turn the hear lights on the car would go completely dark. I would also hear some relay cilicking. After some heavy duty sluthing I found that the wire that connects the alternator (B+) was corroded internally from the heat of the starter and exhaust. The wire was green and brittle. Hence, under loads it could not supply the electrical system with proper voltage/amperage. I ended up replacing that whole section of wire and eliminated the problem completely.

Good Luck!

 

P.S.

I ment the (B+) to starter terminal where batt cable connects to starter. Your problem is hear related so check all the wires down there as well.

 

I already changed the B+ terminal... I unplugged the guage wire from the alternator... and I am pretty sure that the batter is now charging... but for some reason, when the car gets hot, it won't start... perhaps too much timing?? Or not enough starter power... not sure.

 

Oops... nope. Forget that last one. The clicking under the dash stopped.. but it is still low on the voltage. I still don't know whatz wrong.

Thanks,
John

 

heh....umm..i know this might be a little off but...becuase of that same problem in my Mopar muscle car....i might be able to help somewhat.....first....check all your ignition wires....if theres a bare wire...its grounding out and voltage is leaving the system....check all your contacts for corrosion and bareness....and check for crap or grim in your distributor and what not....otherwise....batterys sometimes just wont hold a charge if thier old.....take it easy.....i hope you can fix it

 

Just some thoughts:

1. When you stated the car is driven "a bit", exactly how much is that? If all your trips are < 5-10 minutes, that may not be enough to recharge the energy lost from starting it.

2. Exactly how much voltage is the alternator putting out with the engine running?

3. With the engine running at fast idle, does the voltage remain constant with the high current accessories on (lights, fan, wipers, etc.)? Does the voltage drop when the RPM goes to idle (if so, this is normal)?

4. Is anything draining the battery with the ignition off? The dome light(s), radio and ECM (that you probably don't have) will draw a lot less than 1 ampere - more like 100mA (0.1 ampere) total. An easy way to check this is to disconnect the negative battery cable (with the engine off of course, and everything off), then touch the negative post. You should see a very small spark when you make connection, barely noticable. If you see a large spark, the you have a large current draw which will need to be eliminated. Remove a fuse, one at a time and repeat the test until the large spark goes away. Don't forget to disconnect anything else, such as the alternator connectors, that don't go through the fuse box. Find the source of this current draw, and you should solve the problem.

 

Do you have headers? Maybe it's a heat soak problem with the starter, itself, & you need to heat shield it.

Tim