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Old 27 April 2017, 01:35 AM
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LoganS
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Default Battery relocation

Hey all,

I'm looking at relocating my battery to the rear of the car using an Odyssey pc680 and some 50mm welding cable RATED TO 365amps.


Is that the right size cable?

When I place a circuit breaker or fuse in line by the battery, how many amps do I want it to be?

Thanks,
Old 27 April 2017, 09:27 AM
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alcazar
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Get the thickest cables you can. I advise both positive AND negative cables, but some folk go for earthing through the body.

As for fuses, be careful, you cannot fuse the cable between battery and starter, modern starters can pull 500 Amps for first cranking, which would blow any fuse. Modern cars have the main fuse/circuit breaker in the feed to the alternator and car electrics, AFTER the starter cable has branched off.
Old 27 April 2017, 07:27 PM
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LoganS
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Ive seen 0 gauge used in most set ups that I've found online, some even use smaller.

50mm welding cable seems to be the same cross section as 0gauge but it is rated for more amps.

My plan was to ground the battery to the body.

run the live to a bus bar in the engine bay and then branch off to where it needs to go.

Would you say the ground from the engine is best run back to the battery rather then to the body?

Last edited by LoganS; 27 April 2017 at 07:28 PM.
Old 27 April 2017, 10:13 PM
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1509joe
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The body would be ok but you'll need an earth strap to the engine from the body up front. Sure that's the way it basically is anyway.
Old 27 April 2017, 10:27 PM
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agw_01
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Originally Posted by alcazar
Get the thickest cables you can. I advise both positive AND negative cables, but some folk go for earthing through the body.

As for fuses, be careful, you cannot fuse the cable between battery and starter, modern starters can pull 500 Amps for first cranking, which would blow any fuse. Modern cars have the main fuse/circuit breaker in the feed to the alternator and car electrics, AFTER the starter cable has branched off.
Of course you can fuse the cable between the starter and battery. Not doing so would mean an unfused cable running the whole length of the car. What if it was to chafe and short out!

I've done several battery to boot conversions (albeit not on a Subaru) and have never blown a 150 amp fuse... even while trying to get one of them started after a conversion to Megasquirt.

Last edited by agw_01; 27 April 2017 at 10:39 PM.
Old 27 April 2017, 11:33 PM
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LoganS
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Ok cool, there's one at the moment which goes from somewhere near the starter to the battery. So I would ground this one to the body.

Last edited by LoganS; 27 April 2017 at 11:36 PM.
Old 27 April 2017, 11:40 PM
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LoganS
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agw_01 I've read a few threads where 150 amps have been ample (hehe) I probably will put one inline just as a safe guard. Worst case is it blows and I put something a little bigger in.
Old 27 April 2017, 11:54 PM
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agw_01
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Each to their own and all that.

I'm sure a well routed cable, protected in some conduit would be ok but given that a cable will be subject to vibrations and movement over time, it's a no-brainer to not have an extra layer of protection.

I've seen what can happen when un-fused electrical connections go wrong, and the results aren't pretty!




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