Voltage Drop

[Derrick824]

Either way, more voltage drop in the back then in the front means the power isn't transferring adequately which means more power wire to carry the current.

[MECHMAN]

Either way, more voltage drop in the back then in the front means the power isn't transferring adequately which means more power wire to carry the current.

Sorry, I didn't see where mentioned a front - back voltage comparison.

[dmanson]

Either way, more voltage drop in the back then in the front means the power isn't transferring adequately which means more power wire to carry the current.

with that being said then he does need a minimum of 4 runs of 1/0 gauge + and 4 of - ......... and i said at minimum.

[kingsuv]

I would do the 4 runs of each to the back. I would also ground the amps the the batteries not the car. You still can ground the batteries to the car and still do the runs to the front.

[mrrairai]

I agree at least 4 runs. I would have 1 run per battery in the back.

[EricM9104]

Ok, I have a multiple alternator setup and MLA module up front, along with an optima red top.

In the back I have 4 optima yellow tops. Big 3 is done, and all wiring is 1/0. I have 2 runs of 1/0 from the front to back, and 1 run of 1/0 ground.

All connections are attatched well.

On a burp at the front of the car the voltage is 14.5ish, but in back it drops to 12.5 at the amp.

I've checked all my batts too see if something is wrong with them and they rest at 12.8.

What else could it be?

I already ordered another roll of 1/0 and I'll be putting more in next week hopefully, but even that shouldn't make a 2v difference should it?

Thanks

Sorry, I didn't see where mentioned a front - back voltage comparison.

L2read bro.

[tejcurrent]

Yeah, I'm waiting on wire to add more runs of 1/0. I ordered a 50ft roll of kicker 1/0, so end of next week I'll have another 3-4 runs. Another few weeks I'll probably finish with 8 runs + and 4 runs -.

Even still, I've had a 1v difference before, but 2+ volts doesn't make sense to me. I expected some drop, but with the wire not popping a 250a fuse I dont see how it could be reaching its 300a 'capacity'. I'm going to do a few more tests and see if I can't get this solved.

My amps are grounded to the batteries in back, which are then grounded to the frame/chassis. They are all connected, and then all run to an aluminum grounding buss bar. The bus bar is grounded to the frame/chassis a few times, and then grounded to the front battery.

This was at around 1500-2000rpms, with 1 factory 130a alternator and 3 380a iraggi alternators.

Thanks for the help guys- I'm hoping the wire will help it just doesn't seem like that's it for some reason though.

[kingsuv]

Thats just it, your not getting a full 300+ amps draw from the wire cause theres only so much "water" that can flow through the hose. The alts can't charge the back batteries fast enough for the system. Another thing to consider is, most alts won't peak charge less then 1200 rpm.

I would really look at your grounds. Bad or not enough grounding will hurt just as much as not enough power wire.

I would also look at the terminals. The cheap lead ones will hurt the power transfer from wire to battery. I had some cheap ones and lost a full volt from the wire to the battery terminal.

[missinglink]

Steel makes a great resistor. I am in the middle of building a new load bank, and was just doing some calculations for a set of 100 amp load resistors...

A piece of .187 diameter steel bar 110 inches long is .147 ohms - and that will soak up 100 amps with enough cooling.

If your frame has a resistance of .01 ohms, you are sucking up some power heating the vehicle.

With high currents, the ground path needs to be equal to the rest of the system.

'Link

[tejcurrent]

Cool guys, thanks. I'm waiting for the spools of wire to see if that is it for sure. I will be more than doubling what I have in there now, and then shortly after 2 runs per amp/alt. I'll update then I guess, thanks for all the input.