Wire or Cable size? 100ahr 12.8V Lifepo4

Batteries, Chargers, and Battery Management Systems.
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hydeal2   1 µW

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Joined: Dec 05 2017 7:48pm

Wire or Cable size? 100ahr 12.8V Lifepo4

Post by hydeal2 » Dec 05 2017 8:16pm

Building own battery packs for my boat trolling motor and outboard. Need to know the wire size and type to use from cell terminal to battery pack case terminal?

-Length of cable on both terminals is maximum 7".
-Compression ring terminals used at both ends.
-Water tight PVC Case.
-Thru Panel stainless terminals used on case.
-600 amp 1-2 second/cycle/200 amp 20 second cycle/80 amp continuous

Any help would be great-full!

dustNbone   10 kW

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Location: Vancouver, BC

Re: Wire or Cable size? 100ahr 12.8V Lifepo4

Post by dustNbone » Dec 05 2017 8:44pm

For a run like that I'd want at least 2AWG, but 4 would probably be fine. But generally for inside the box like that, I cram in the biggest one I can reasonably fit.

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Sunder   100 MW

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Location: Sydney, Australia

Re: Wire or Cable size? 100ahr 12.8V Lifepo4

Post by Sunder » Dec 05 2017 9:42pm

7" of 4 AWG @ 600A = 51 watt loss
7" of 2 AWG @ 600A = 33 watt loss

7" of 4AWG @ 200A = 5.7 watt loss
7" of 2AWG @ 200A = 3.6 watt loss

7" of 4AWG @ 80A = <1w loss
7" of 2AWG @ 80A = <1w loss

As long as your times are accurate, I'd say dustNbone is spot on. I would not like to see 51w of heat dumped across just 7" of cable for any significant period. Short cables = low resistance, but short cable = smaller heat sink...
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 on 36S
eCar: Mitsubishi Outlander PHEV... Waiting for warranty to expire
eHouse: Still on grid, but with LTO batteries and 3kw LF inverter...

After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca

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fechter   100 GW

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Location: California Bay Area, USA

Re: Wire or Cable size? 100ahr 12.8V Lifepo4

Post by fechter » Dec 06 2017 9:45am

How much current does the motor actually take?
"One test is worth a thousand opinions"

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