Bed mounted battery question
 

A friend of mine was helping me with an electrical issue on my truck. My battery is located in the bed. I have a short ground going to the frame near the battery. The positive running thru the frame to the starter.. I have never had any starting issues since moving the battery.

He said that I should also have a ground going from the battery to a mounting bolt on the starter.. Is this necessary?

He solved my other issues by installing other ground from engine to frame and body.

Re: Bed mounted battery question
 

This has caused a debate for some time. First, a fact: iron has approx. 6 times the resistance[resistivity] of copper(copper is 1.6 x 10 ^-8 ohm meters and iron is around 9.6 x 10^-8:whatever this means:lol:). We've experienced starter problems w/installs like yours that were cured with running the long ground wire. We attributed it to a voltage drop(loss) between the battery, thru the frame, and the starter. If we apply Ohm's law, assume only 30 amps being pulled by the starter(watching older ammeters, it would likely be more like 50-60 amps), assume the steel frame has only 1/10 of 1 ohm more resistance than a proper copper cable, it would result in a voltage drop/loss of 3 volts--E=IxR--E=30x1/10...=3 volts! This would leave only 9 volts left to operate the 12-volt starter... **NOTE: nothing has even been mentioned about ampacity, another twist on amp-flow comparison thru different materials.**

You decide, after considering the assumptions. Your, and others' conclusions will not hurt my feelings. Were I to install, for myself, a rear batt., I would try the short ground wire from neg. batt. post to the frame, first. I'd install a good cable ground from starter to frame. If it worked well, job done. If starter showed any sign of "dragging", I'd run a battery-cable from batt-ground post all the way to the starter.

HTH rather than confuses!
Sam

Re: Bed mounted battery question
 

Wow Sam!! You went all scientific on it!! Some of that I didn't take into consideration with the iron vs. copper carrying current.

Thanks again for the info and will take all that into consideration going forward..

I do have a newly installed ground from block to frame. Shouldn't that be as good as starter bolt to frame?

If a copper ground is needed going from battery to starter, what gauge would be needed? Same as the positive, or smaller?

Re: Bed mounted battery question
 

I do have a newly installed ground from block to frame. Shouldn't that be as good as starter bolt to frame?..............Should be ok.

If a copper ground is needed going from battery to starter, what gauge would be needed? Same as the positive, or smaller?........Same as positive.

Luck to you & keep up the good work. (Sorry for delayed response.:waah:)
sam

Re: Bed mounted battery question
 

No worries on the delay!!

Thanks again Sam!