Advice on wire sizes.

DIY Builds
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Hello all, I am looking for advice on wiring sizes. My config. Flipsky Vesc 6.6, 12s 5p using 21700 Molicel 42a, and dual motor 6384 190kv.

Here is what I do not understand. The power cable going to the Vesc is made out of 8 gauge silicon wire braided which I have read can run 40 - 50 amps. The vesc with dual motors can put out continuous 100amps each for a total of 200amps with both motors continuous and then up to 400amps burst. This sounds ludicrous.

  1. How can a VESC supply 200amps continuous when the power cable coming in at 8 gauge can only support 50 amps?

  2. How crazy do I need to go with pure nickel strip when I connect my parallel groups in series with one another when one piece of .20mm x 7mmm strip can only carry 14 - 20amps?

Thanks for your future advice for this noob.

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Copied from a @rusins telegram post

battery
Updated ampacity for hobby grade copper wire with many strands!!!

6AWG | 300A
8AWG | 190A
10AWG | 140A (XT-90 recommended)
12AWG | 88.4A (XT-60 recommended)
14AWG | 55.6A
16AWG | 35A
18AWG | 22A
20AWG | 13.87A
22AWG | 8.73A
24AWG | 5A
26AWG | 3.5A
28AWG | 1.25A
30AWG | 0.8A

This is because you rarely pull 200a, and when you do it’s on for a few seconds.

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Those ratings look awfully generous. Where did you get these numbers Raisins? @rusins

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  1. like @PixelatedPolyeurthan said. You’ll maybe pull 15A battery current continous.
    I personally pull about 10A battery current on average over a whole 30km ride on my mountainborad with about 19-22Wh/km as my consumption.

  2. Build your battery like this:

    image
    image4032×3024 2.89 MB
    that way there is plenty of nickel to carry big crurrents (: (It’s 0.2x25mm nickel)

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IIRC

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Wow, I haven’t seen 25mm before is that readily available? I usually just get my 7-8mm strips from Ebay. That looks like more than enough to get between groups.

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Be careful with ebay strips, they could be nickle plated steel so give them a quick saltwater test before using.

You can get the wider strips on aliexpress, steel city store is the supplier most of us use but they take 3 months to ship

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I originally took them from a chart in Chinese by @BindingsMcGee. They seem consistent with tests I’ve seen online. Note that these are absolute maximums, not recommended ones. If you need to draw a few amps more, I highly suggest going up a wire size rather than risking it.

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Thanks for the tip Anubis! I just learned a new tip with the salt water. And to to think I was even minored in Chemistry in College.

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The beginning of your battery pack build looks nice and clean. May I ask what kind of spot welder you are using? Your welds look perfect. I have a Sunnko 709a with the hand attachment. You said you are using .2mm. The stupid handheld spot welder attachment doesn’t work as well as the probes that are straight from the machine.
I had it turned up to the highest setting and still could not get the handheld attachment to weld .2mm.

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That Sunco welder will produce much better welds at 220v if you have access to an appropriate outlet. You could even run one yourself after a couple YouTube videos. However, you would have to swap out the cord.

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Kweld. It’s probably the best welder money can buy (unless U spend thousands xd)
I ditched the sunkko 1,5 years ago and never regret it

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Thanks for the input, right now I’ve got a 20amp dedicated right out of the service panel. I just sit there with my light on in the basement and work right there. Is there a 110v/220v switch in the back? I’ll have to look.

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I would assume there is, but it’s no guarantee. Simeon is right about the kweld, it’s incredible.

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