This has been driving me nuts for almost a year...

[Intense-Dakota]

Ok, I will try to make this as easy for you guys as possible:

I have a 1970 Dart with a 318. Last year, I went to start it up in late summer, and of course, I had to jump it. Now, comes the fun. It started up fine, let it charge for a few minutes, and then disconnected one side of the jumper cable, it is still running fine. Disconnected the other side, and it died instsantly. So, I tried it again, disconnecting the oposite side of the cable, boom - died instantly again. No matter which side (+ or -) I disconnect last, it dies. First thought was alternator. So I took it down to the parts store, and had it tested. It tested perfect. Next, I checked all the power and ground lines I could find, all looked ok, but just to be safe, I cleaned them all and re-tightened them. After that, I even tried using the jumper cables as grounds in a few spots just to test that, and still the same problem.

So, my last though is the voltage regulator on the fire wall, but I wanted your opinions first.

Previous to this, I did have a problem with the battery staying fully charged if it sat for more then a few days at a time, but I have since put in a new battery also just to be sure. Oh, and the battery is relocated in the trunck.

Please help if you can, I have the mopar itch and summer is here. I need to hear that rumble while I am actually driving down the street and not teathered to my Jeep via a jumper cable.

 

[rednesss]

"This has been driving me nuts for almost a year..."

What, the steering wheel in your pants??? (rim shot)

 

[1968FormulaS340]

What gauge of wire are you running for the trunk mount? Are you sure your battery ground is mounted correctly?

If you still have the under hood cables temporarily remount the battery under the hood with the standard cables and see if the problem is still there.

If the problem goes away you have something with the long run of the cable to the trunk. Make sure it hasn't rubbed through the insolation and is grounding.

 

[1968FormulaS340]

Im betting it's all related to the trunk mount. This is one place where you can't skimp on cable thickness.

 

[Intense-Dakota]

I believe it is single or double ot. Either way, this is the same setup that I was running for over 4 years, and I tried moving it back up front when it started. But thanks for the ideas.. keep em coming.

 

[demon seed]

Are you running the negative cable from the battery in the trunk all the way back to the engine block and are you connecting the jumper cables from your truck battery right to the + and - posts of the trunk battery.

Terry

 

[cudajim]

It sounds like you may not be charging properly. Do a quick voltage measurement while it's running. You should be reading at least 14.0 volts. Measure both at the alternator output and the battery, they should be really close because they are theoretically tied together but through the ammeter if it's stock wiring. If the voltage is low (like closer to 12v) you're not charging and you should suspect the regulator or subsequent wiring since you already had the alternator tested. Good luck.

 

[chayden]

I think your battery is shorted internally and check your grounds from the engine to the chassis and from chassis to engine block. change the battery and try again

 

[chayden]

sorrry , didn't read the whole post befor I replied sounds like a bad connection somewhere or an intermittant or medium resistance short. if it was the rear mounted battery, you would have melted cables or severe arcing which would be east to see

 

[cudaman51]

disconect the battery cables at both ends and check the resistance between the cables and to ground. it should be over 1000000. ohms it could be a little lower but not a lot.this check is with nothing hooked to the wires. you will be checking the insulation.It would be grate if you could use a megger but an ohm meter will do.

 

[Intense-Dakota]

thanks for all the inputs, I am still trying stuff, as I have not found the problem yet.

 

[ramcharger]

Even a new battery will be killed if left in a car for a year without being trickle charged every couple months. I say dead battery that's sucking so much juice your alternator can't keep up enough voltage to run the car.

 

[briankaplan]

Get the battery charged and test it properly. Then check ALL
the ground cables. Check your engine to chassis ground and then
the neg cable to the battery. Good luck.

 

[Badart]

Even a new battery will be killed if left in a car for a year without being trickle charged every couple months. I say dead battery that's sucking so much juice your alternator can't keep up enough voltage to run the car.

Had the same problem in a rally-cross car a few years ago with the battery mounted in the trunk. I would have to leave the battery tender on it while parked. By the end of the weekend my battery was dead. I ended up running 0 gauge wire and had much better results.