Lukas Build Log

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49

But that is 250A for the total system draw
So say about 65A per ESC/motor , chart indicates 12ga, at least in areas that are getting only 65A.
If your running from a busbar r out to the ESC than 10 should be fine. From the bats to the busbar you will need 6ga by the looks of it…but, is each battery putting out 250A - no. If you have 4 batts then that is again approx 65A per bat and 130A if you have 2 bats, so max 10ga. The bats to the switch/busbar is a bottle neck and will get the most power, if you are doing it that way, so make that robust. IMHO

Sorry, forgot the bats in series to get 48V - thus drawing 130A from just 2 batts

Cheers. Patrick

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With the 22x14 props(75kg static thrust), each ESC pulls over 110A at max load

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@Codemonkey is that something you measured directly?

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Paul did. I calculated that it would need 121A, but Paul insisted it was closer to 110A

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Not sure where I said that, but at full throttle with the 22x14 I measured 96A peek.

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Ok thanks for the link, I think I was talking about the max the ESC I tested could handle. With the newer motors the number is closer to 96A.

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For both the 96A data how did you measure the current draw? If the ESC is rough with the supply (allowing for the DC bus caps in the ESC - although they will likely have an average ESR), then the measured current can be incorrect on the wrong device/if the device is placed too close to other current carrying devices.

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It was measured inline with a watt meter like this one Other RC Model Vehicle Parts & Accessories for sale | eBay

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I can can get you a prop if you want to measure yourself. More measurements the better.

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Hi
So max draw per motor arm is 96A – so 384A total???
Thx

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yes it can burst up to that amperage for a half second or so but the continuous amp draw is not that.

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I am trying to figure with power rating for my registration application
image

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My answer to that question was 16 kW in total. i measured 75A per motor controller steady state at 50V. I measured mine with a LEM HASS-50 and watched the values on an oscilloscope

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i did 18.5kw - 48v X surge of 384A

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I think if I was making a registration application I’d put down 16kw with the confidence of knowing that the registration authority would have absolutely no ability (or interest) of proving you wrong :wink:

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Paul-Oz - Based on your statement, then it is ok to put just about anything that is within the ballpark.
but maybe there should be a standard rating listed by Openppg in case the authorities go to check.
Cheers

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I had a bit of time to play more with the unit tonight. Here’s what I learnt:

The range of PWM (go signal from throttle) is quite wide - more so than my servo tester so I did a throttle calibration. The response range now seems better.

PWM
PWM1266×944 239 KB

I also changed the ESC timing to HIGH. The motors now run much smoother through the throttle range. None of that ugly resonating (phase mis-firing) that was happening at mid throttle on the INT default setting.
Here’s a link to the document that describes how to do this (different model, process the same):
http://www.hobbywing.com/products/enpdf/xrotorpro25acircular.pdf
Note - you will need separate 5 volts to power your throttle as you connect battery under full throttle to get into these modes.

I’m still trying to find a more elegant solution to attaching the batteries. How are you guys doing it?

5 Likes
67

Great info - thx
cheers

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Thanks for the information Lukas! I wonder why the instructions that came with these ESC’s didn’t have these programming instructions.

When you say you did a throttle calibration do you mean on the ESC using step 2 in the link you provided or did you do some programming on the throttle controller itself?

It says intermediate timing is more efficient and produces less heat but if high timing makes the resonating go away wouldn’t that be more efficient and produce less heat?

Do you think it would be possible to program all 4 ESC’s at the same time so I don’t have to take the back plate off to disconnect the others? Is the reason we need a separate 5v so that you can power on the throttle controller before powering on the ESC’s? What if I just held down the throttle all the way when turning the switch on, would that put it into program mode? I thought the extra leads on the ESC are for programming but we don’t need those for this right?

Sorry for asking so many questions. I’ve programmed RC ESC’s before but this is a just a little different.