I struggle figuring out electrical issues like this so I have become pretty trained to just keeping a trickle charger maintenance routine going on for a number of years instead of addressing this issue. Went a little over a month without trickle charging, and yesterday battery was dead.

12 volt system was there when I bought truck 24 years ago. Has 1956 gauges with 53 face plates on it. 12 volt generator, has starter button. Electric fan runs off of relay from battery. This has all been on here for at least 7 years. I can't pinpoint when I noticed the drain happening. I paid 6 years ago to have engine block boiled out, bored and redone on the 239 fatty. Maybe around when I got the truck back, but still not positive on timing.

Any good ideas to help begin to isolate the area or eliminate areas of the drain are appreciated

 

Mornin Todd

what you have to do is isolate each electrical circuit until you find it.. hopefully you have a fuse panel somewhere. Since it's a low current leak you can remove the negative cable from the battery and place an amp meter between the cable and the battery terminal. Most volt-ohm-amp meters have a amp mode that will let you read low amp draws...usually less than one amp. It will show how much current the leaking circuit is pulling... then one at a time remove fuses for each circuit. If the fuse pulling isn't an option, you gotta start pulling or disconnecting individual components.... bulbs, radio, horn...

When you find the circuit the ampmeter will drop to zero. then it's a matter of tracing that circuit to find the gremlin. Time consuming but not difficult. Good luck, those small problems are sometimes the most difficult to fix. I had an add on "roady" satellite receiver that would kill mine in about a week sitting at the airport deck if I forgot to turn off.. I don't know how many 'goodies' you have in your truck but some common ones that might give you trouble are...

dirty battery or cables... you can have a draw from a corroded or wet battery top... make sure battery and connections are clean and corrosion free
instrument panel lights wired to 12v directly instead of switched 12v
radio... some newer radios draw minute current to retain memory
dome light switch circuit
glove box switch
crossed up wiring that maybe bleeding voltage off...
brake light switch that sticks and leaves the brake lights on dim

have you looked at the truck at night ?? that might show a bulb still burning after you shut the truck down...

hope it helps

john

 

Hello. Battery drains on these trucks should be easy to find, they just don't have a lot of stuff. First things first. If the battery just sits around most of the time chances are it is a bit weak just from sitting. I would test the battery and make sure it is up to snuff. Make sure the terminals are clean and tight and the top of the battery is clean. To test for a draw you need to connect a test light in series to the negative battery cable and the battery post. An ammeter is better but a test light will work. If the test light is glowing bright you have a draw. Start disconnecting fuses one by one until the light goes out. When and if you pull a fuse that kills the light, figure out what is on that circuit that is causing your problem. If after all the fuses have been checked and the light is still on check the alternator or generator wiring. Just make sure you do indeed have a draw and it is not a battery that just sits and is a couple of years old. Good luck!

 

Thanks John and 1951 for the helpful start.
I don't have a fuse panel, so it will be time consuming but sure do appreciate the help in right direction.
I will report back when/if i can trace it.
Battery is less than one year old interstate. And had it checked ok this spring at store after I stored in indoors for winter. top is clean and tight so I will begin with procedure you describe.

 

John has some great advice and a good procedure here. If you don have a volt ohm meter or are not familiar with one you could also take a 12 volt test light or a 12 volt bulb with some test leads soldered on to it and connect it between the neg battery post and cable. Any current running through the bulb will light it. The brighter the bulb the more current. Then just as John says disconnect things until the light goes out. Do you have an alternator? I know you mentioned generator. Some folks interchange the terms
Reason I am asking is if its an alternator , there might be a shorted diode causing low charging voltage and a parasitic current draw.
Edit;
My apologies to f31951 as he already gave this information. Somehow I missed it. F3 did a great job addressing this. Thanks!

 

It is a 12 volt generator. forgot what year and make it came out of. Late 50's something