you would be better off with 1 400a fuse than 2 200a fuses. or placing 2 200a fuses and tieing both ends togeather to make 1 400a fuse.


I give up this thing delets all the empty spaces GRRRRRRRRRRRRRRR!
More Than Zero

 

get the ground wire they use on private jets... it's more pliable than that monstercable crap, strands are way finer and the cross section is about the size of a quarter.

 

I wouldn't recommend that. This would allow up to 400 amps to pass through a single 2 gauge wire. Although it’s not likely, what if one of the wires disconnected, or the terminations became corroded such that one wire effectively was out of the circuit? Now you have a 400 amp fuse protecting a single 2 gauge wire.

If you go with the 2 wire route, I would recommend using separate fuses for each run. That way, if something goes wrong, you won't fry the wire (or worse... I won't even say it).

 

Quick,

There are alot of very good answers previously stated and here's something that seems to have been missed.

Use 1 fuse (same size as you would for the single 1/0 cable) and tie both the #2 wires together at the single fuse holder as well as at the battery (it's called a paralell lug and is how all large systems are done to minimize large wire costs as well as a few other reasons). Do try to keep the lengths similar and don't worry about losing 1 wire because if that happens you'll have a potential short from the free wire or hot spot on the lug.

Also, for best current carrying capacity as well as longevity, use welding cable if you can get it at a reasonable price. It's hands down better but can be extremely expensive if you don't have access to discards.

 

I am no expert ,but i have some practical knowledge. I ran a 0/1 guage to the back for the battery with one 200 amp fuse. That lasted about 2 weeks before it blow during start up. 300amp fuse has been the deal for about 12 months. Search for 300 amp fuse and you can find them for sale in some high end car audio sites.

 

Wow, this thread generated a lot of interest on how to minimize a .1V drop

 

sorry guy but I do not agree with you, the 400a fuse will blow in short order if a cable becomes shorted. this is the SOP method of doing this and is just as safe as a single conductor solution.

 

I don't think he is talking about a short. I think he is saying that one of the cables would somehow disconnect (without shorting to ground). Then the other cable could (in theory) try to carry a 400amp load and burn the car down with it.

Anyway, thanks for all the great info on this guys. It is amazing how something as simple as running a wire can get complicated with so many different approaches.

Does anyone know what the avg normal load is (without a big stereo thumping), say with the the headlights and both elec fans running? Guess I could go measure it (but I'm lazy).

 

Thats exactly what I was refering to. I know its not likely, but just thought I'd throw it out there.

 

and that is what I thought you were saying, but a #2 wire WILL blow a 400a fuse in zero time if the single #2 cable becomes shorted. This is why the par. conductor setup is quite safe. the fuse rating is for overload (defined as several mins, like 60, of running at 400a +) a short is like 1000a for as long as it takes the fuse to blow (around 5/60th of a second depending on conditions) wile a short is such that under a short condition it will carry in excess of 5000a for long enough to blow the fuse. so a short is not your worry and the C5 will very rarely have a current draw high enough to damage a #2 conductor (outside of the starter) in an overload condition. the only reason the 400a fuses are in here is to protect in case of a short and they will do that.

If you look at the stock setup you will notice that there is NO fuse inline with the starter (due to the fact that the power system is power limiting and the battery would run out of juce before the stock wire, about #2 in size, would burn up), in this case it would be wise to include a fuse due to the increased length of the run and the possability of damage. This fuse is there to protect against a short not an overload and the parallel setup would be fine.



More Than Zero P.E.

BTW the issue of corroded or lose connections would normally announce them selves the first time he tried to start the car and the starter would not start the car due to voltage drop.

 

if the load exceeds the capacity of your alternator for extended periods of time then your batt. would be dead. I believe that the stock alternator is 90 or 140 amp rated so this will give you a good idea of the max sustained load.

More Than Zero

BTW measuring a DC current at this amp level is not a simple task (clip on amp probes only work for AC)

 

I don't see why there is such a concern with the alternator charging if the battery is relocated to the rear. The new Z06 has a rear mounted battery and the ouput wire from the alternator is connected to the starter battery lug. The Z06 positive battery cable is upsized from the standard C6 by about 40%. The alternator output wire is protected by a fusible link. The distribution block wiring is also upsized from the battery in the Z06 as well. It is not proteced in any way. As MTO mentioned it is current limited to the capacity of the battery which in a bolted fault type short circuit sitution the battery runs out pretty darn quick! From the looks of the battery cable in a new Z06 it appears to be about a 1/0 size or slightly larger.

 

How to make something simple so complicated that it's not practical...I like Doug's approach...simple is better

 

Go to your local RV dealer and get an idea because they do it all the time. Also, your alternator is going to be hard pressed to charge both batteries should they ever both die. Just something to consider.

 

I never planned on running the alt wire back to the battery. I was planning on a distribution block from the start. The discussion was about wire size and if two 2ga was better than one 1/0ga.


The discussion was never about two batteries. Just moving it to the rear and what type of wire would be best to use.

Read guys.

 

Sorry QS, the way this was written it sounded like 2 batteries. "remote mount a battery" where "remote mount the battery" might have been a little more accurate.
I would do the one wire and one fuse set up though. The two fuse set up wouldn't do any good. Although the current divides, if you blew one fuse at 200 amp, the other would follow instantly.

 

This is what I love about this site, so many experts!

More Than Zero

aka David L. Cash P.E. (Electrical Engineer)