The Stovebolt Site Forums The Shop Area The Electrical Bay 1958 With Dead Battery

My '58 (235 with floor starter)has a dead battery if I leave it for more than 2 weeks without driving it. I have replaced the battery after it would not take a charge (thanks AC DELCO!)it was under warranty for being less than the maximum number of months old. Same thing exists with new battery. Switch is off after parked in the garage, key removed. Battery was very dead, under 5 volts across the terminals, no cables connected. I used a high end DC amp meter placing leads between the positive battery terminal and the positive battery cable (that goes to the starter solenoid). Meter did not show any current with key off, meter works, because it showed current with key on. I sent the starter back to the local shop that rebuilt it when the truck was completed 3 years ago. They tested it could not find any short between the main lug and the small lug to the case. I have not tested the dash switch with ohm meter yet. Plan to remove it from the dash tomorrow and see if there is any leak thru that the dc amp meter did not pickup. During drive periods the amp meter shows good charge and will go back to a 'running' state when the battery reaches ~12.75 - 13.1 volts. Checked battery voltage with multi meter with key and motor off.
I am really quite frustrated with not being able to find a short with an electrical system that is so simple.
Does anyone have any suggestions of what to look at other than drive the truck more often and disconnecting the positive cable after each drive?

Try disconnecting a battery cable when you park the truck and see if the battery will hold a charge that way. There's got to be a slight parasitic drain somewhere if you can maintain a charge by interrupting the circuit.

I like to use an ice pick type test light to check for parasitic drains. Connect the light between a disconnected cable and the battery post it came off of. If the light glows, even dimly, there's a small drain somewhere. Start disabling circuits such as the ignition switch, light switch, generator or alternator, voltage regulator, etc. until the drain goes away, then do an in-depth diagnosis of the circuit with the drain.
Jerry

After following Jerry's directions you find no issues, check to see if the brake light switch is sticking keeping the brake lights on. If it is, replace the spring. Mine would do that until I got programmed to slip my foot behind the brake pedal and pull back on it.

Generator or has it been changed to an alternator? If generator the regulator might be sticking, an alternator can also create a parasitic drain on the system.

The brake light switch is a great suggestion, do you happen to have a glove box light? If so that might be draining the battery.

As suggested disconnect one cable and use a test light between the cable and the battery post. If it lights you have enough of a draw to bring the battery down. Start removing fuses or disconnecting items one at a time til the light no longer comes on.

Good points, thanks for making me remember that I installed a new alternator, rebuilt Delco from NAPA. I do not have a glove box light; yet.
I did check the brake lights this morning after I went out to see if the battery would take a charge. They did not appear to be on. I will remove the lens to see if they are just barely on and not bright enough to glow thru the lens.
Battery took over-night charge, the truck started, stock amp meter showed discharge; after 90 seconds at idle, the amp meter went to the center position. Battery showed 14.7vDC when I turned the truck off.
The truck does have a new wiring harness (M&H) that was installed during rebuild.
No radio, it does have electric wipers, a signal stat four-way flasher, headlights, cab interior light (I'll pull the cover off it and check the bulb element today also), chrome knobbed cigarette lighter and gas gauge for electrical circuit items. Pretty simple.
I will follow Jerry's suggestion with the ice-pick test light as the next move this morning.
The headlights on low beam are great. All four are NAPA halogen replacement units. When I switch to high-beam, the contacts on the switch kick out. I used a clamp on amp meter to check current on high beams, its above 18a! I am working thru installing "spike-edge" washers on each ground wire of each headlight and tail light. With taillights complete and one high-beam done, high current draw still exists. Looking at installing relay system for this issue if the rest of the grounding washers do not reduce current draw.
I will post results of the 'ice-pick' test as soon as I get all other checks completed. Thanks for advice and ideas for the draining issue so-far!!!

Ice pick between the positive terminal on battery and the cable end that goes to the top of the starter; no light. Removed tail light lens and interior light lens; no glow on either one. Will run it tonight on cruise; disconnect battery when I put it away to see if battery maintains charge.

Can't help much with diagnostics, but if it's weeks between your drives I'd disconnect the negative battery cable. My truck has sat six months over winter before without being started once and when I connected the negative cable the engine cranked like it was a new battery.

A master battery disconnect switch under the hood is a good idea for vehicles that don't get driven regularly. Just be sure to get one that's capable of carrying the full starter current load. I used to use a 600 amp disconnect on the race cars we built. One quick twist of the wrist, and all the electrical power is disconnected until the next time the vehicle is run. You can find them on Amazon or Evil-Bay.

https://www.amazon.com/Cllena-Curre...ords=battery+disconnect+switch&psc=1

Jerry

Looks like you have done all the "normal" things, maybe it it time to look for the obscure. I have heard of alternators "leaking" or gently drawing (reverse drain through suspect diodes) current from the battery after shut down. Maybe, in the circumstance that you know you will not be driving the truck for a couple of weeks, disconnect the alternator BAT connection, and see what happens. A little off the wall, but if nothing else works something to try.
don

Battery maintains charge when disconnected.

Jerry, I enter the truck in AACA shows, they frown on non-stock parts. In an effort to hide the disconnect switch; I looked and I think that I can build a bracket to mount the switch under the battery tray/frame. Cable would come off the top of the battery, loop down to under the tray, go to one side of the disconnect and then go from the other side of the disconnect to the stud on the starter. This switch is meant to be used on the positive cable, correct?

I will try disconnecting the alternator from the system when parked in between drives and see if the battery maintains. Thanks!

As long as you interrupt the circuit, it really doesn't make a difference which cable gets the disconnect. It can go into either the positive or negative cable circuit.
Jerry

Jerry is right about disconnect switch, mine is under hood near the battery and cuts the ground cable. Been 4 years now with no problems. Nice anti theft device as well....

Most shows request the battery be disconnected when on display, it might be worthwhile checking regulations.

Ed

I use one of these on the negative terminal of the battery. No need for a fancy installation. Sure makes it handy to turn off the power when working on anything electrical. I'm showing the HF version, but they are available at any FLAPS.

https://www.harborfreight.com/battery-disconnect-switch-97853.html

Matt

The tricky part of using that connector is keeping the contacts from corroding. Particularly on a 6 volt system, even a tiny bit of resistance in a connection can limit the current available to the starter, resulting in low cranking speed.

The racing associations where I used to compete wanted a quick-disconnect switch available to emergency crews in case of a crash with fuel spillage, so we mounted the switch I linked to on the roll cage in easy reach from outside the cars.
Jerry

That disconnect switch might work with 2-gauge 6v cable, but would it work with 00-gauge 6v cable?