I have a k30 diesel (12v) that im moving the batteries behind the cab. Im running 2 walmart batteries, I think they are both like 800cca's. I have some 1 gauge welding cable, do I need two + wires running to the front? Also what about the ground, can I get away with just grounding the batteries straight to the frame and nothing else?
CK5
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Movin the batteries to the back how should I wire them?
- Thread starter protechk5
- Start date
i would not suggest grounding to the frame in the rear... some will argue they've done it and it works.. but there are inherent issues doing it...
in series, 1 power wire, 1 grd running forward.....
Fred_M1010
1/2 ton status
Ehh, I think you mean in parallel, not in series...
It's 12V, not 24V
It's 12V, not 24V
doh, 5 am brainfart...
tourdog
Registered Member
batterys
Don't foget to run the biggest wire you can from the alt. as well it wil charge better and run the biggest wire for ground as well.
Don't foget to run the biggest wire you can from the alt. as well it wil charge better and run the biggest wire for ground as well.
The frame is not the best to use as a ground. The starter motor is the largest AMP draw of anything on/in the truck aside from a winch and the ground cable should go directly from the battery to the engine block. A nice large gauge welding cable is best used for a long run of cable over buying bulk battery cable long enough for the job. Welding cable Has many more strands of copper than a battery cable does which means it can handle more AMPs with less resistance. Naturally the postive cable will need to go up to the starter motor. Don't forget to also ground from the battery to the frame since the battery is getting moved and the stock cables that had a provision for doing so will be long gone.
While I agree with running a ground to the engine block you should still run a ground to the frame. Otherwise you will have issues with anything that uses the frame for ground (like the ECU). Your motor is sitting on rubber motor mounts, they dont conduct 
You will also want to increase the guage of wire going from the alternator to battery. Since you have increased the length of wire you will need a bigger guage wire.
You will also want to increase the guage of wire going from the alternator to battery. Since you have increased the length of wire you will need a bigger guage wire.
While I agree with running a ground to the engine block you should still run a ground to the frame. Otherwise you will have issues with anything that uses the frame for ground (like the ECU). Your motor is sitting on rubber motor mounts, they dont conduct
You will also want to increase the guage of wire going from the alternator to battery. Since you have increased the length of wire you will need a bigger guage wire.
I think you missed this part of my reply.
Also there is no need to increase the wire size from the alt to the "battery" since that wire actually goes to the starter and has nothing to do with where the battery is located. That wire needs to be a larger gauge if you increase the AMP rating of the alternator.
The wire from the alternator should run straight to the battery. When your car is running your alternator is supplying all the current. When selecting wire size you need to also take into account the distance of the wire. If you increase the length of the wire and the current stays the same you must also increase the guage of the wire.
Mike D
1/2 ton status
All the above suggestions are good, however one thing you may run into is that if the batteries are located behind the cab ( outside ) the batteries may not charge up completely in the winter ( if you live in a cold climate or high altitude ). I had a 1975 Audi Fox that has the engine in the front and the battery in the trunk. It always cranked REAL slow in winter. I finally had to install a massive ( and expensive ) battery designed for a Mercedes. The bottom line was the battery would not fully charge unless the battery was around 70 degrees F. That is why they locate the batteries inthe engine compartment ( to take advantage of the overall warmer underhood environment ).
If you live in an area that gets snow install two 12v battery heaters. Switch them on a few minutes after the engine is started and running smoothly. A rear defroster switch and a heavy duty relay would automatically shut the heaters off after 10 minutes. Good luck.
If you live in an area that gets snow install two 12v battery heaters. Switch them on a few minutes after the engine is started and running smoothly. A rear defroster switch and a heavy duty relay would automatically shut the heaters off after 10 minutes. Good luck.
It may have been covered but I didn't read all the posts, but grommet any and all sheet metal you run the cable thru no matter how thick the shething seems to be, it WILL wear thru and short out, ask me how I know. 
rufusbooth
1/2 ton status
I agree with 4x4High on this one. The alternator wire runs down to the starter on these trucks. From there the charge current runs up the batt cable to charge the battery. In this case you are already going to put in a MASSIVE positive battery cable from the starter to the battery which takes care of the long run current losses. No need to muck with the alternator charge wire unless you are upgrading the alternator to a higher amp unit.
Rufus
wasted wages
1 ton status
Nothing wrong with using the frame at the batteries as a grounding point as long as you have the same size cable or ground strap between the frame and engine block at the front of the truck.
Buff the frame down to the steel,,use star lock washers and 3/8 bolts and thick washers and you should have no problem.
I have a 3/8 stud welded to my cage and use this at the back of the buggy,,and another stud welded to the cage in the engine bay. and use a flat braided ground strap to the engine block.
Buff the frame down to the steel,,use star lock washers and 3/8 bolts and thick washers and you should have no problem.
I have a 3/8 stud welded to my cage and use this at the back of the buggy,,and another stud welded to the cage in the engine bay. and use a flat braided ground strap to the engine block.
Aluminum and then copper are the best repsectively for being used as a conductor. Both of these are non magnetic and have the least amount of resistance.
wasted wages
1 ton status
If we were talking about parasitic losses or High end stereo systems,,, I would agree with you 100 %...but for all intents and purposes,,,12 volts at 300 amps crusing through aluminum,,copper or steel ain't going to make much difference to a starter or winch motor......just sayin' 
big4x4ride
1/2 ton status
Copper is better than aluminum, silver is better than copper..
You are correct, i made a mistake and now i'm owning up to it.
At 59.6 × 106 S/m copper has the second highest electrical conductivity of any element, just after silver. This high value is due to virtually all the valence electrons (one per atom) taking part in conduction. The resulting free electrons in the copper amount to a huge charge density of 13.6x109 C/m3. This high charge density is responsible for the rather slow drift velocity of currents in copper cable (drift velocity may be calculated as the ratio of current density to charge density). For instance, at a current density of 5x106 A/m2 (typically, the maximum current density present in household wiring and grid distribution) the drift velocity is just a little over ⅓ mm/s.[26]
