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amp drop rate

For all things Electrical.

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amp drop rate

Post by G_loomis »

The main power cable for my winch is currently about 1 metre long.

I am setting up a dual battery system and have no room under the bonnet for the 2nd battery. So it looks like it has to go out the back either under/on top of the tray.

This would mean that the new power cable would be about 5-6 mtrs long. Would the amount of Amp droppage be severe enough to affect the winch?..and if so...how do I get around the problem?

Is it simply a case of bigger cable?...how big is big enough?...Have heard of blokes just running 2 cables...but that seems a little dodge to me.
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Post by mickyd555 »

run two cables in parralell. its not dodge, its quite good. What is the caurrent rating on the existing winch?

what size cable have you used from the existing battery.

At a guess id say run 2 x 70mm cables
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Post by G_loomis »

mickyd555 wrote:run two cables in parralell. its not dodge, its quite good. What is the caurrent rating on the existing winch?

what size cable have you used from the existing battery.

At a guess id say run 2 x 70mm cables
70mm cable....as in 70mm diameter? :shock:
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Post by 84ZOOKSTA »

70mm2.
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Post by chimpboy »

84ZOOKSTA wrote:70mm2.
Which is roughly a 10mm core. Pretty heavy stuff.

I agree with MickyD that it's not dodgy to run two cables, but I am just wondering why not run the winch from the battery that's in the engine bay?

If you really want to use one battery for starting and the other for winching, you will have less trouble running the starter motor from the battery that's in the back.
This is not legal advice.
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Post by mickyd555 »

G_loomis wrote:
mickyd555 wrote:run two cables in parralell. its not dodge, its quite good. What is the caurrent rating on the existing winch?

what size cable have you used from the existing battery.

At a guess id say run 2 x 70mm cables
70mm cable....as in 70mm diameter? :shock:
sorry to scare ya dude........... :D

70mm squared cable shoule be good for about 220 Amps (without looking in the book??) im guessing the winch will be rated at about 350 amps, and then take voltage drop into account.........it sounds right. I can work it out for you exactly tomorow when i get to work if ya want, but i will need the proper rating of the winch.

if you go down a size in cable your looking at 50mm squared cable then and i think you will only get about 150 amps out of that.....again i cant remember exactly, but at 150 per core your still only looking at 300 amps....not to mention price difference would be negligible on a 10m length, especially if you can get a nice electrician member of OL to help you out. ;)

now that ive typed all that maybe you might need 95mm cable :idea: :idea:
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Post by 6.5 rangie »

Where and how much for 70mm2 cable.
Wholesalers have 35mm2 flex and i can get that fairly cheap, i will be running both my batteries in the back to reduce the weight over the front, but need find cable and know the current rating of it. Really should do some maximum demand/volt drop calculations but its just easier to ask
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Post by mickyd555 »

6.5 rangie wrote:Where and how much for 70mm2 cable.
Wholesalers have 35mm2 flex and i can get that fairly cheap, i will be running both my batteries in the back to reduce the weight over the front, but need find cable and know the current rating of it. Really should do some maximum demand/volt drop calculations but its just easier to ask
run 3 x 35's then, 35 should get you 120 amps i think?? but you will have to see how it goes on price when you need 3 times as much..
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Post by 6.5 rangie »

Yeah thats my thoughts, about $5.60 a metre for 35mm2 sdi FLEX, not XLPE. Will get a price on 70mm2 and 95mm2 flex sdi.
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Post by -Scott- »

Mount the winch under the tray comp style. Right next to the battery. So your long cable only needs to be large enough to deal with charge current.

Considering the front mount: all the above discussion only deals with current rating, and the ability to sustain the winch current for long duration. It's not considering voltage drop, which I expect to be considerable under full load. I expect 350A will create quite a voltage drop over a 6 m run , so the winch motor won't actually receive 12V, so it won't actually draw 350A, and you'll never achieve peak performance.

Anybody want to do the sums?

Scott
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Post by mickyd555 »

NJ SWB wrote:Mount the winch under the tray comp style. Right next to the battery. So your long cable only needs to be large enough to deal with charge current.

Considering the front mount: all the above discussion only deals with current rating, and the ability to sustain the winch current for long duration. It's not considering voltage drop, which I expect to be considerable under full load. I expect 350A will create quite a voltage drop over a 6 m run , so the winch motor won't actually receive 12V, so it won't actually draw 350A, and you'll never achieve peak performance.

Anybody want to do the sums?

Scott
nope, thats why i didnt........... ;)
Its Sunday, ill do it tomorow and post it up......... :roll:
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Post by DamTriton »

http://www.stealth316.com/2-wire-resistance.htm

should give you a ballpark figure

0.7V drop at 350A, 6m, 0 AWG (53.4mm2)
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