battery keeps goin' south?

[BUXMAN66]

yeah,i got a wierd one for you electrical guru's out there! so any hoo,i buy me a nice tach. get it installed,run my lines to -1).ground on the body.2).light - to my headlight switch. 3).line to my hei dist. 4).power lead to switched power-key on. so how come everything works fine and dandy when on but something keeps killing my brand new interstate battery? when you push in on the lights it correctly turns off the light in the tach.,so there's no power drain there.obviously,when you turn off the ignition the rpm's go back down to "0".i have never had problems with the battery being dead after a couple of days until i hooked up the light to the tach. would there happen to be some kinda diode or something that is causing a slow ,trickle draw?checked the condition of my alternator by removing my positive battery cable, and the engine continued to run.would a bad voltage regulator do this?i have currently the old style external voltage reg. (was a good reason to go buy a 1 wire chrome 100 amp.,waiting on ups to bring it!) thanks for any help

[chevyman 68 C/10]

Turn everything off and see if there is a spark at the bat cable when you conect and disconect the cables. If so disconect the light to the tach and retry The spark will stop when you find the culprit.
I have never been a fan of interstate batteries, when I was buing used cars and salvage that was the only bat that you could count on to be a dud.

[gmcnorton]

FIRST MAKE SURE EVERYTHING IS TURNED OFF... THEN DISCONNECT NEG BATTERY TERMINAL, HOOK TEST LIGHT TO CABLE AND TOUCH NEG BATTERY TERMINAL LIGHT SHOULD BE VERY DIM OR OUT COMPLETELY, PULL FUSES TILL LIGHT GOES OUT THEN YOU KNOW WHICH CIRCUT YOU SHOULD CHECK. IN YOUR CASE I'D START WITH TACH HOOK UP.. OR IF YOU HAVE METER YOU SHOULDN'T HAVE NO MORE THAN 50 MILLIAMPS OF DRAW ON GOOD SYSTEM.. HOPE TAHT HELPS YOU

[71GMC_3/4T]

Disconnect the light you ran to the headlight wire and see if the problem goes away.
I think the dimmable lights put 12V on one side of the light all the time and the headlight switch pulls the other side of the lamp to ground through the big wirewound variable resistor in the headlight switch. It may be finding a path to ground somewhere other than where it should be.

[Project1970]

Originally posted by chevyman 68 C/10
Turn everything off and see if there is a spark at the bat cable when you conect and disconect the cables. If so disconect the light to the tach and retry The spark will stop when you find the culprit.
I have never been a fan of interstate batteries, when I was buing used cars and salvage that was the only bat that you could count on to be a dud.

Slightly OT, but the Interstate in my truck is the only battery I've ever seen go more than 1 year in one of our cars - 4 years and counting, now! (Of course, the others were a small handful of Delcos and a lot of Autozone batteries...)

[Riveted1]

You guys rock. Gmcnorton, I used your technique (b/c I was having this problem, too). It ended up being a tach wire that the p/o had wired into an unswitched power connector in the fuse block. Sure did save me a lot of headaches!! Thanks again.

[Longhorn Man]

When pulling fuses with the test light or multi-meter wired to the battery as described above, if you get all the fuses out and your still getting a drain, unplug the alt. They can crap out inside and drain...but still charge the vehicle when running.

[gmcnorton]

glad i could help.. thats why this board is great. usually you can get anything fixed with help from someone on this board. it seem there is someone to help with any problem.

[SWINGSAX68]

Buxman66,
Sound like you got something on constantly....do the check like these guys suggested.....you'll find it.