jonesm8

buddies truck was running on one battery for a long time (no issues there). He's looking to sell and put the second batter back in, reattached the positive cable to the drivers side battery. While attempting to connect the passenger side battery, it was obvious no current was passing through the cables. All the cables are connected at the correct location and corrosion has been cleaned off. Both batteries have charge.

Any thoughts? I'm completely stumped and he's ready to pull his hair out.

jstone44720

Was the newly installed battery any good? Not trying to be a smarty here, just serious. A battery setting can die without too much issue.

NE frmhnd

The ground cables on those batteries should be tied together as well. If you look at it, the left battery supplies juice to all the accesories like the FSS and such. The right one only supplies power to the starter and anything that's grounded through the body.

CarlJensen

What year truck? My 95, and all others I have seen, have the batteries in parallel. Has the battery been load tested? It can show good on a meter yet fall on it's face with a load...

jonesm8

Both batteries work very well on the drivers side as a single batter set up. Both exhibit the same behavior on the passenger side. I should have said both batteries were tested before posting, apologies.

His is also a 98'.

Busboy

Check the main fuse at the front of the PDC where the battery power cables attach (fuse box under the hood) I forget what that fuse is called at the mo.

gorms

I've got a 98 and just peeked under the hood to verify how everything is hooked up. Passenger side battery has one positve, from other battery, and 2 grounds. Heavy gauge to engine block and smaller gauge to fender.

Drivers battery has 3 grounds, 2 are smaller gauge. One to fender on top and one dissapears down near the frame rail, probably hits the frame. Also has the heavy cable to the engine block.

Positive term. has heavy gauge to passenger battery, heavy gauge to starter post, smaller gauge to main fuse block, another smaller gauge from alternator, and 2 fusible links to the grid heaters.

Both batteries share all duties, because they are connected in parrallel with that heavy gauge (2/0) cable.

With that said, I'm confused. How do you know there is no current being drawn from the passenger (secondary) battery? With the driver's battery in place and all cables hooked up to it you should not see any current passing (I'm guessing here you're looking for an arc when the terminal hits the battery post?) from the pass. bat. untill you hit the starter. Nature of the beast. Check for voltage with a meter while off and running (when grids aren't cycling). You should see same voltage on both batteries, around 12.6 off and around 14 running.

You should have all electrics working with either battery in place, basically. And with the drivers battery hooked up, adding the passenger battery does not put any demand on it untill there is a heavy load like the starter or grid heaters.... the whole reason they put 2 batteries in these trucks.

Make sense?

Tate

Disconnect the crossover cable from the driverside battery cable. Check with a meter to make sure you have voltage. You'd need an induction style clamp to check for current draw on that cable to see what its able to pass.

Right now you've described a problem that, as far as your posting has shown, you haven't tested for yet, so it may be a phantom issue at this point. Run us through the steps you've gone through to come to the conclusion you have.

joem

I had issues where the cross over connects to the drivers side batt. Once I dis-assembled and cleaned it I was able to start the truck with only the passanger side batt hooked up!

jonesm8

I appreciate all the replies, I'll see my friend tonight or tomorrow and we're going to give these suggestions a try.

Again, MANY thanks for the help

9812vram

I'm curious how you reached this conclusion? Pretty hard to tell that there's no current going through the cables unless you're checking it with an inductive ammeter and cranking the engine at the same time... or checking it for a couple amps while the engine is running (showing it's charging - won't be much amps if the battery is full)