The Stovebolt Site Forums The Shop Area The Electrical Bay What is going on with my Battery?

I had my 1951 4400 at the shop for brake work and wiring for tail/stop lights recently and brought it home on a wet Sunday evening. The truck ran fine all the way - about a 6 mile drive but stalled as I pulled into my driveway which is a good 15/20 degree grade. I tried to start it again but no go, the battery struggled to crank the engine over a few times and then nothing. Since it was at the end of the driveway and to far from the house to run a cord for the charger, I used my 2004 Silverado to jump it. It started immediately and I had the cables connected for maybe a minute or less and then drove the rest of the way up the driveway and parked it for the night. It was a cold, dark and rainy night and it could wait until the next day. The next morning I thought I would try to start it with the battery as it was left the night before. The engine cranked over like there was a new battery in it and the truck started quickly. I let it run for a bit and noticed there is no movement of the ammeter when I rev the engine a bit. I shut it off and put a dvm on the battery to get 6.28V I started it again and notice the battery voltage go to 6.15V and again, no change if I rev the engine. The guy I bought the truck from said the battery was new last year but who knows? I had the generator rebuilt earlier this year. Anybody have any ideas what might be happening?

Check your battery cables and a clean the connections including the ground connections. One of the causes of hot start cranking problems is dirty connections. As current passes through a dirty connection, that connection gets very hot, which further increases resistance at that point. After sitting for a couple hours, the connection cools, allowing enough current to pass to run the starter, only to increase resistance again.

Clean connections and undamaged cables are a must.
Kent

Dirty voltage regulator points, probably. With the engine running at a fast idle connect a jumper wire from the "F" terminal (at either the generator or the regulator) to ground, and see if the ammeter needle jumps to full charge. If it does, remove the regulator cover, disconnect the BAT wire at the regulator, and give the 3 sets of points a good scrubbing with a piece of business card or a slice cut from an index card. Reconnect the BAT wire, start the engine, and check to see if the ammeter deflects to the + side. DO NOT USE SANDPAPER OR A FILE ON REGULATOR POINTS! They open and close with a slight wiping action, and scratches, even tiny ones, will make them stick.
Jerry

Thanks for the tips! To late about not using abrasive paper on the regulator points though, unfortunately for me. I will try some 2000 grit polishing film to see if I can correct that error. Headed out to work on it now.

Find the charging system problem and fix it. If the voltage at the battery posts (not the cable clamps) isn't above 7 volts at around 1500 RPM or so, the battery isn't getting charged.
Jerry

Again, thanks for the tips and comments. This morning, I disconnected the battery and cleaned the posts and cable ends. I also removed the ground strap from the frame and cleaned that and applied some silicone grease to the connection. Again, the truck started promptly so I drove it to my mechanic Freds shop who proceeded to trouble shoot it. He found the problem after about 20 minutes of poking around and looking at my service manual. The dumb owner of the truck had the generator rebuilt but did not connect the wires to the proper terminals on the generator. Fred switched them around and all was good. He gets another bottle of Bulleit Rye Whiskey.

OK- - - -one final test. Charge the battery- - - - -unless you plan on driving a couple of hundred miles without shutting the engine off, the generator isn't up to the task of fully charging a 6 volt battery. Once that is done, do the voltage check at fast idle again- - - -you should see 7.5 volts +/- a couple of tenths of a volt. This test MUST be done against a fully charged battery. If you don't get a good reading, carefully increase or decrease the spring tension on the regulator coil behind the "F" terminal of the regulator to get the charging voltage right.
Jerry