1949 Chevy, Battery Draining

[Coach529]

Ever since I put a V8 in Henry I have had issues with the battery draining. It has not been a big deal since it gets driven almost daily, but if it sits for more than a couple days the battery goes dead.

Most of the factory wiring is still in place, just changed some stuff up to get rid of the foot pedal starter and install a key switch.

Running a 2 wire alternator now. I had been running a 1 wire alternator with the stock 216.

Any ideas??

[Highsider]

Mine was drawing from a third-to-a-half of an amp, when the key was off.
Last week I started pulling fuses and seems the A/C is the culprit.

It looked like messing with the fuse reset whatever and fixed the "issue".
But it still does it and I haven't pursued the problem.

[OrrieG]

It will be the last fused circuit you check. At least is was on my 21 circuit fuse box. Turned out to be the tach was wired to a hot circuit and not ignition circuit and was drawing power even when ignition was turned off.

[mobileortho]

I had a similar issue with mine. Turned out to be a bad alternator, it wouldn't shut off completely when the key was off. I had to return two brand new units to the local parts store until I got one that worked properly.

[mr48chev]

I'd go along with what's different than before and look there first.

With the two wire alternator, how is the exciter wire hooked Up? Through a keyed on circuit or direct? Direct might cause a draw when the switch is off but not cause the engine to keep running.

Also check across the top of the battery from one post or another to see if you have current flowing across dirt or moisture on top of the battery. I've seen some serious draws with dirty battery tops in the past including one that killed the battery in three or four hours on a student's truck when I was teaching.

[Coach529]

Originally Posted by mr48chev

I'd go along with what's different than before and look there first.

With the two wire alternator, how is the exciter wire hooked Up? Through a keyed on circuit or direct? Direct might cause a draw when the switch is off but not cause the engine to keep running.

Also check across the top of the battery from one post or another to see if you have current flowing across dirt or moisture on top of the battery. I've seen some serious draws with dirty battery tops in the past including one that killed the battery in three or four hours on a student's truck when I was teaching.

Exciter is hooked up on a keyed circuit.

Alternator is new. Battery is new and clean.

Stock fuse block and voltage regulator is still in place. It is pretty hacked together but all the connections are good. It needs a complete rewire......but I would like to get this figured out first.

[mr48chev]

From 50 years of experience, "new" or "freshly rebuilt" doesn't always mean that a part is in perfect shape and functions perfectly. Still if it is on the keyed circuit that should be good enough.

As I suggested, check for voltage running across the top of the battery to make sure you don't have a drain there. It doesn't take a lot of dirt and moisture to make a path for electricity.

Other things I've run into are a clock in the radio that draws more amps than expected and drains a battery over a few days. I've seen brake light switches that will stick on or pedals that will drop enough if they don't have a return spring to let the switch turn the brake lights on. interior lights switched on and forgotten especially if they don't put out a lot of light to begin with.
I had one student who didn't take his custom 64 Chevy to work at Safeway at night because he didn't want to get it dinged in the parking lot and left it parked at his house. Every morning the battery was too low to start the car and he had to jump it to drive to school and we spent a number of hours checking every part and piece of the electrical system. About that time he was fussing about it to his mom and she says "Oh, your brother and his friends stand outside and play your car stereo in the evenings. A bit of a heated discussion with his 13 year old brother cured the problem.

[NEWFISHER]

Grab an Ohm meter and check for draw across each fused circuit. One should be higher than the rest and just start individually removing each "tied in" circuit or item until the draw across the circuit falls.

[mobileortho]

Originally Posted by mobileortho

I had a similar issue with mine. Turned out to be a bad alternator, it wouldn't shut off completely when the key was off. I had to return two brand new units to the local parts store until I got one that worked properly.

I should clarify that it was the alternator that would not shut off completely & not the engine. Both the battery & alternator were new. It took me awhile to figure it out but one evening I went into the garage & noticed a faint whine coming from the engine compartment & realized what it was. I had to take back two "new" units to Advance Auto before I got one that worked. The guy at the store tested them & they were bad. He even tested one straight off the shelf and it was bad too!

[dubie]

i had the same problem and it turned out to be one wire feeding continuous power to the old external voltage regulator.