bnold

I posted this question in another thread, but felt it was worth a thread of its own... I have been throwing the idea around of relocating the batteries to under the bed, in the toolbox, on the frame whatever to free up some room in the engine compartment... wiring the positive side is really straight forward the grounds are another story. Lets see what opinions are out there


"Ok been getting things together for sending the batteries to the back of the bus... Concerned about the grounds though

Currently there are 2 1/0 grounds one going from one battery to the block and the other from the auxiliary to the block.

Also from the auxiliary is a 8ga to the frame and a 10 ga to the body
Also from the main is a 10ga to the body and then and 8ga that disappears into the harness... S109 in the wiring diagram.

So I was planning on grounding the batts direct to the frame using 2/0 cable.. What to do with all the loose ends?

Connect the engine grounds to the frame?
Connect the chassis grounds to the frame?
Connect the 'other' batt grounds to the frame?

Any advise on how to ensure a secure reliable ground connection to the frame?"

mcoleman

When moving the battery to the rear of all my racecars I've always ran an engine to frame ground wire and a battery to frame ground wire.

wannadiesel

Yeah, just run a ground cable from the batteries to the frame. Everything that was on the negative battery post should be moved to the frame.

Clean the frame down to bare metal where the grounds will be, and use a star washer. Spray the connections with battery terminal grease after you get them tight.

06RAM2500

Don't forget to run an independent ground to the ECM.

bnold

Does the ECM have an independent ground stock? is it the ground that disappears into the harness... haven't followed it through the wiring diagram yet...

06RAM2500

Yes, otherwise you can end up with a dead or funky acting ECM. It'll be a bigger cable than the ones bolting to the fenders. It's normally attached to one of the bolts that hold it to the engine.

carl48

you will ruin a lot of stuff if you ground to the frame with the 2/0, run the grounds the same as they are now, on a cold morning i have measured over 1,000 amps starting current, if you ground the 2/0 to the frame when you start the motor the current passes through the small wire to the starter and through the u joints and gearing to get to the starter the arcing causes failure in these parts and the potential difference will kill the ecm

bnold

So do you suggest running 2/0 ground wire to the block in addition to grounding the battery to the frame? As apposed to just 2/0 from battery to frame and then 2/0 from frame to block in the engine compartment?

Makes really no difference to me as the wire is free.... Just want to make sure I dont run the risk of frying electronics!

bent valves

Running a wire from battery negative to the frame and another from the frame to the engine will work but it is not the best way to do it. That is called a “Daisy chain” connection and is prone to electrical noise pick-up. A better connection is a “Star” connection where one wire from battery negative connects to the frame and a separate wire connects from negative to the engine. A third connection from the negative to the PDC on the fender is needed.

Here is the problem with the daisy chain connection. The auxiliary connection you mentioned in your first post is connected to the battery negative. If one of your new frame connections or engine block to frame connections gets corroded it will cause a voltage drop. This voltage drop will be greatest when starting or when the grid heaters operate (large currents). As the voltage drop increases the ground reference for sensors (APPS, MAP, IAT etc.) will get corrupted and cause problems. You will have a much more reliable system by running separate wires.

bnold

Ok so the consensus is run the battery to the frame and attach all the small gauge current grounds to the frame

Then run a 2/0 wire from the neg post to the engine block.

Possibly run a separate run from the neg post to the PDC?
How about a short lead from the 2/0 running to the block to the PDC?

Thanks for the input

bent valves

After thinking about how I would do this, the easiest way is to run a single heavy gauge wire from the negative of your relocated batteries and stop about where the driver’s side battery used to be. Put a heavy ring terminal on the wire and make this the center of the star connections. A second heavy wire would connect to the star at this point and then connect to the frame. A third heavy wire connected to the star would then connect to the engine block. All other smaller wires will connect to the star point also. If you can make the star connections using a heavy brass bar and brass screws or bolts threaded into this bar along with some dielectric grease, this would be ideal. The star connection brass buss bar will be the ground reference for all circuits related to the engine and can be expanded to include lights and other add-on circuits.
In my opinion this is how the truck wiring should have been done from the factory to prevent grounding problems that seem to come up as our trucks get older.