Never ending story… the 18650 question…

Hey together! I plan an all terrain 4WD for the cold winter in Russia. For now I think about 4x 170-190kV motors (6474 or 6480) with a 12s battery and ESCape ESC. If everything went how I plan, I will have space for a 6-8p battery. I calculated the max. battery current with 50Ax4= 200A. The question is, do I really reach that 200A current? Or better to say 200A for a longer time (like hill climb)?

I don´t have any experience how much Amps this setup could draw off road. Maybe somebody can share his values with me?

I also made some calculation based on nkon prices: VTC5 2600mA 30A 7p max 210A 231€ VTC6 3120mA 30A 7p max 210A 298€ VTC5A 2600mA 35A 6p max 210A 241€ (special offer price for 3,35€ per cell) Q30 3000mA 15A 8p max 120A 278€ 25R 2500mA 20A 8p max 160A 200€

Based on the numbers the VTC5A would be the lightest and cheapest option. But that´s only the numbers. If somebody can speak out of experience, which would be the best choice for it, I would be very interested to hear it!

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Not an expert here, but I’ve never heard of an esk8 drawing 200 amps. Maybe a racing-build would, but I guess lipos would be a better choice for short time, high amp draw. And li-ions and cold Russian weather doesn’t seem like a good match. As I understand it, cold weather and batteries means poor performance, risk of failure and shortened battery life.

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30q batteries are good for 20a continuous. That’s why most use them because 3ah and 20a discharge. But for you at 7-8p you have options.

50a x 4 is going to feel like a rocket. Like a big one. However this is going to be a peak current. Your high P count will be more for range. It’s possible on 4wd you might not even reach 200a on a 4wd board. Someone else with a mountain board and 4wd needs to chime in.

If you are average weight, 12V60A will shoot you like a rocket during acceleration.

that´s one more question, I´m not sure yet. Just because it can be able to put out 200A, does not mean it´s also practical and controllable. just if I look on my dual drive which I limited to 35A, I reach them for the time I speed up. just for that time, but I reach them. the question how it will be with four motors. The amps just go up linear, or it slow down because of 4 motors which will have less work to do…

rocket yeh :joy: that´s exactly why I ask. What will be the max current I can expect and is also possible to handle on the board.

It’s roughly split between the number of motors.

I have not seen more than 40-60A continuous yet. You would have to be pretty skilled, courageous and athletic to stay on the board above that. I think spikes of around 100-150A can be reached with big awd cans but that is less than a sec and uncommon. If you have a slow blow fuse of 40-60A you should always be fine.

That means I would be fine with a 12s5-6p 30q or even 4p vtc6🤔

um… hell yes. 12s5p is a LOT

https://www.youtube.com/watch?v=ufFDLvNCwR8 by @Ackmaniac Maybe not the best source because it is a dual drive but better than nothing. :slight_smile: 82 amp start is bloody fast (3:39)

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Its not the best to let the batteries cool below 0 degrees since theres some liquid that can be frozen and make the cell puff itself if i remember well, reccomend you to read a bit on batteries and low temperatures But if they are in an enclosure they will heat up itself from the use and the heat will stay inside

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I don’t worry so much about the temperature. As i usually come from warm place and after I start driving they should heat up as you said. Tried it last year with my drone and -20. The only thing is that the range will be not as much as in summer. For real hart times I have one way heating pads for hands. Just put it in the enclosure and should hold everything round about 20-25 degrees for 6-8h

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I want to give you some genral advice regarding your batteries and low temperatures.

  1. Don’t not store the batteries for very long times below 5°C (so don’t store the board in a freezing garage for example)

  2. When the cells they will produce heat which will help to keep the battery at reasonable temperatures (btwmake sure to not hammer on the throttle when you know they are cold, the max. Amp draw ratings do not really apply when the battery is far off the testing conditions) they won’t work as efficient on low temp and battery temperatures below -15°C are very dangurous over all you should make to not use it when the actual cells are < -5°C.

  3. Therefor you should insulate the battery a (regular electrical insulation+ thermal insulation) working insulation material for example would be silicone, non flammable products like expanded glass granule/foam glass or mineral wool(might cause problems when it gets wet) .

  4. By the way after a ride in the snow when you store the board you should check for moisture build up caused by the temperature differences, allow them to dry of fully befor you ride or charge up again.

And to ask your question which cell you should choose … you can basicly use any of these you listed they are all great candidates for a esk8 battery. As long you have a high parallel config (>6-8P) you should be perfectly safe with either of them.

The 200A draw is a burst draw at best, I mean we speak of ~8.5KW power for a board with 20-55 kg. And since you want reasonable speeds (I guess < 65 km/h) this will be geared down by a 4.5 - 6.5 ratio that is probably a torque greater than you can use on basicly any ground anyway, even with 4WD.

So what I want to make clear, any of these cells should work in the appropriate parallel battery setup, the 200A will be a burst at best. You should choose between these cells by reliability, the capacity and cost.

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Thx for the long explanation! I will not store the batteries under 5 degrees and for sure don’t start from a cold battery. There I had already some not so good experience with my drone batteries :sweat_smile:. I usually always open my enclosure after a ride, so there shouldn’t be a problem with water inside too.

But just to understand, that 82a in the video is for one vesc only. So in this case 160a for a start up on flat ground.

When running dual motors you can set the app to show values for two vescs to give realistic values for total power / amp draw etcetera. What makes you think this 82a is for one vesc only? Doesn’t seem right. Also, Max batt is set to 50 A, so the 82 is most probably the two vescs combined.

Depends on the board you are building. If it’s going to look like this: 4WD Monster you can easy reach more than 200A when driving in snow or loose sand…

That’s a monster board. Some big power sucking wheels as well.

Where on earth did you get 30 and 35A from a 18650 cell as CDR? Testing by mooch and the datasheet shows nowhere near 30A. I don’t see why you would need 200A continues for off road, remeber that battery amps is not = motor amps.