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Old 06-06-2020, 18:33   #1
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Parallel jumper cable lengths

Wiring up 4 100 lithium batteryís in parallel. I know all the jumpers should be the same length and take off either center or opposite ends. I get a little confused as to once Iím on the last terminal..all my jumpers are 13Ē post to post. When I get to the last post on the negative side I go into a victoron bmv shunt. And the last post on the positive goes to a 400amp class t fuse. Does the length of the last jumper have to be equal? They will be on opposite ends of the bank so I was planning on running the last jumper the length of the batteryís back to the front so all will be in the same spot....hereís a simplified example on the left is what Iím planning on doing, on the right is what I hope I donít have to do. Seems kind of a silly question to me. But Iíve been pondering it..

Also how critical is the length of the jumpers? Since my too, didnít do 2/0 wire I had the ďshopĒ make up my 6 cables some are 13 some are 12 some 11. I was thinking since Iím using 2/0 wire the inch or 2 of resistance isnít gonna be that big of a deal?
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Old 06-06-2020, 18:35   #2
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Re: Parallel jumper cable lengths

Actually the pic is upside down but the one with the one neg wire back is what the plan was . The second drawing shows the last jumper having to be 13Ē I assume not since itís not jumping to anything?
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Old 06-06-2020, 18:45   #3
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Re: Parallel jumper cable lengths

I think sometimes we get too wrapped around the axle chasing perfection when honestly close is good enough. I don’t do lithium, but if I were to I wouldn’t worry at all about plus or minus one inch jumpers myself.
Next thing we will be told that only pure copper bus bars are acceptable.
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Old 06-06-2020, 19:02   #4
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Re: Parallel jumper cable lengths

FWIW, I wouldn't call them any of them "jumper cables".
(Jumper cables are used to "jump start" an engine )


And you are talking about two different type of cabling here.

1. Interconnects between battery terminals
2. External connections from the outside pos/neg terminals.

All of the 1's should be as near as possible to the same length.
The length of the 2's is immaterial.
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Old 06-06-2020, 19:35   #5
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Re: Parallel jumper cable lengths

Gotcha Iíll sleep better tonight
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Old 07-06-2020, 12:36   #6
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Re: Parallel jumper cable lengths

Not part of the question but 2/0 wire will not handle 400 amps. The fuse should be smaller.

As it is the wire is the fuse.
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Old 07-06-2020, 12:36   #7
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Re: Parallel jumper cable lengths

Quote:
Originally Posted by StuM View Post
FWIW, I wouldn't call them any of them "jumper cables".
(Jumper cables are used to "jump start" an engine )


And you are talking about two different type of cabling here.

1. Interconnects between battery terminals
2. External connections from the outside pos/neg terminals.

All of the 1's should be as near as possible to the same length.
The length of the 2's is immaterial.


And just be sure to not have a positive or negative cable cross over or lay adjacent to each other as such close proximity parallel interconnection conductors will not be individually fuse protected and have the potential to short between them if spacing is not kept.

Don't have Red cross or lay up to Black as depicted in this incorrect wiring imaged below. Great way to have Spittenzy Sparkenzy if the insulation of any of the cables degrades.
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