Charging system problem... Shows a charge, but doesn't.

I've been killing my battery a lot lately. It started happening after I got caught in a HUGE rain storm and the car and I got soaked. I nursed her back to the house, stammering while it was still raining and she died in my driveway. I switched out the regulator, ballast resistor and ammeter , polarized it the "Type A" Autolite way per my '59 Chilton's and dried everything out, including the distributor cap, air filter, etc. I charged the battery via jumper cables, she started and showed a charge... I tried the lights and it showed a slight discharge until I gave it some gas and it came back up... same with blinkers and brakes. Took her out for an hour long drive and shut her down. When I got up this morning... stone dead. It's time for a new battery, but I don't want to immediately deplete a new one. I got her started again today, but she died when I pulled a battery cable...

Any suggestions? Should the regulator case be grounded or isolated, as it has a wire leading to a post? Was never a problem before, but something makes me think it may be now.

Jonny

 

Charge your battery with a battery charger before doing anything else. Then pop into your local Autzone or whatever and get them to load test it. Getting a new battery won't help if there is a problem elsewhere.

A quick boost with jumper cables won't charge the battery much, neither will a generator do much in an hour if the battery is really flat.

Once the battery is fully charged, start the engine and run it at about 2500rpm or better and put a volt meter across the battery. You should get a reading of at least 13.75 volts or higher.

Report back when you have tried these steps.

Step by step testing is the key to good diagnosis; electrical stuff is easy to guess at, but diagnosis is better(and usually cheaper, since you only buy what's actually needed)

 

absolutely spot on advice

 

Here is what I would do, charge your batter up a bit turn everything off, remove your negative cable place a test light between the negative cable and the battery terminal (making sure the cable is grounded).

Did the test light go on? If so then you have a short/draw, and there is a good chance that the diode in your alternator went bad when it got rainded and most likely arc'd.

Remove the wires from your alternator. If the test light goes off then you need to replace the diode. If it doesn't start pulling fuses one at a time until you find the draw.

 

I know the battery isn't that great... It's rated at 550 and showing about 380. Regardless, the car shuts off when I pull a lead, so something, somewhere is shorting and draining it, right?

 

This car runs a GENERATOR, not an alternator, if it matters much.

Jonny

 

It does matter, generators produce DC, so there's no rectifier/diodes. Alternators produce AC, with then passes through a rectifier(converts it to DC).

Post #4's bit about diodes doesn't apply in this case

 

You can still check for a draw this way which will help you isolate the issue.