[Build Overview] First ESK8, using non-off-the-shelf parts

ESK8 Electronics
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#1

Hey Everyone! I posted on here earlier, and got some great and super useful advice. Basically, I am in the process of building my first esk8, but I’m trying to, for the most part, avoid off-the-shelf components (just for the fun of it). After doing more research, these are some of the components I shortlisted, and wanted to see if there were any immediate red flags in any of them:

Battery:

  • 16S4P; 60V; 3000W; 12Ah
  • Uses 18650 cells
  • 30A Continuous Discharge; 50A Instantaneous Discharge

Motors: (x2)

  • 24-36 Volt; 2970W
  • 8000-9000rpm
  • Officially rated at 200 KV
  • 0.8A-2.2A (High Current at 120A)
  • Includes Hall Effect Sensor
  • 14 Poles

As for the motor controllers, I’m considering a generic dual VESC.

Specific Questions:

  • Do the specs seem okay/compatible? Is there anything I’m missing or that I should be considering?
  • What benefits does a VESC provide over a generic BLDC controller?
  • A lot of the VESCs I’ve seen accept up to 60V, but they specify the battery pack should be up to 12 or 13s. How does this have a significant impact, and if I use one does it mean I’d have to adhere to that number?
  • I was also considering another motor where I can choose the kV to my liking. However, it requires significantly more current (4600W). I just assumed that the battery pack I found wouldn’t be able to power that and disregarded it. Is this assumption correct?

Thank you so much for reading this and helping me. If any other information is needed please let me know!

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#2

I’m still fairly new to this but I’m willing to offer what I do know. As for ESCs if it says 13s max they mean 13s max, full stop. 200kv is gonna be tough to gear correctly if you’re using 16s. 12s is where voltages start to get dangerous. Relatively dry, adult human skin has a certain amount of resistance and working with 12s or lower is generally considered safe. Please be very careful if you insist on a 16s setup, I cant stress that enough.

Also not understanding how you plan to use a 16s battery pack when the motors you have listed say 24-36v. Do you have a link for these motors?

Kind of curious what charging setup you’re going with. Will you be balance charging or using a combination of power brick and BMS. Do you have a BMS picked out?

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#3

Alright so here’s some things:

Yes. Everything seems to be okay, except your esc choice and motor choice. You need an esc that can handle 16s voltage. If you don’t have one, it’ll get bad. The motors, I have no ideas about 24v-36v limit motors…

This may not work if it’s not rated for 16s. I never tried myself since I keep it with the manufacturer statement.

The ability to change your parameters and amps without the limits of what manufacturers limited the esc to. In other words, if you need more torque, you can do it on vesc. More braking power? Yep vesc can do it.

Yes. If you do not, you will blow up the esc you’re using due to high voltage. If you need an esc that can handle your 16s, get a stormcore 100D.

What generates the power you need for your motors is the esc itself. It will take what it needs from the battery and amplify it accordingly. You must however, limit your battery max current and max regen current to your battery spec ÷2 (dual escs), or you’ll be seeing a fireball.

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#4

Thank you for the reply!

As for ESCs, if it says 13s max they mean 13s max, full stop.

Got it, so in that case it’d be best to stick to normal limits of 12s? I’m looking at other options as well.

Also not understanding how you plan to use a 16s battery pack when the motors you have listed say 24-36v.

Sorry, can’t quite see what’s wrong with that :sweat_smile: Is there something I’m missing?

Kind of curious what charging setup you’re going with.

I was going to make my own pack but I’m a high school student and don’t have access to a welder, so just ended up finding a factory in China that can do it for me. They’re offering the custom battery pack with a BMS and a power brick

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#5

Got it thank you! So if I’m understanding correctly, if I were to step it down to a 12s battery pack, the esc should be okay?

Also, just some questions I had (since we got into current):

  • I thought that 2x 24v motors would be good since I assumed that the dual VESC would be splitting the circuit, and since the two motors are identical, they should provide similar resistances, resulting in ~24v to each motor. Is this a fair assumption to make?
  • If I stepped down to the 12s battery pack I’m considering, it has a rated max instantaneous current of 120A, and I went with a Flipsky dual-VESC (taking in continuous current draw of 100A for dual motor drive), would the setup work? I’m not quite sure how to approach this and was wondering if you might have some insight.
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#6

Motors are not usually the factor unless you’re hill climbing. We usually just go with 63XX motors or 50XX motors if you’re doing a stealthy build like the boosted. Think of it as “do I need motors that can climb 25% graded hills or do I live in a flat land and only want speed”.

This is usually how I would do it.

It will. I’ve heard bad things about flipsky escs though, so I can’t say I recommend it. But if they fixed their errors of the past, then sure. I went with a makerx dv6 for my build.

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#7

Brushless motors typically dont have a maximum voltage. Well they do but its usually well over 100V. Its limited by the insulating properties of each individual enamelled wire wind inside the motor. What manufacturers do is recommend battery voltages that are specific to their intended application. So if you took an ESK8 motor rated for 8s and ran it on 12s you wouldnt have an issue. At least not with the voltage.

Its the kv rating that will cause problems. Too high and it will be difficult to gear down to spin a 70 - 110mm or bigger ESK8 wheel.

If you’re sticking to a 16s setup you’ll need a lower kv motor.

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#8

Ah got it, thanks for the clarification. Yeah the motor says the “Rated Voltage” is 24-36V (see below)

image

If I were to go with the 16s setup, would you recommend maybe going back to 150kV motor or is that even too much?

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#9

Some people usually do 140kv as I’ve seen. I don’t know much about it to be fair.

Edit: found a few things. You could run 16s on 150kv motors, but, It will not make any difference than using 12s 170kv motors though. The factor of using 16s probably benefits charging capability (so I’ve read). But it’ll just heat up the copper windings in the motors since the power sourcing them is too high (hence the motor ratings). You can lower the amps for safety and less heating issues though. But you will run into many issues later on so you should focus on your gearing. But yeah, the lower the kv, just means the lower the power consumption. But issues will still be there.

Personally it just means it’s not necessary for a electric skateboard. It’s probably more beneficial to like bikes or scooters since they usually take a lot of voltage to move.

I would recommend going 12s to avoid massive heating issues and accidents if the esc ever dies due to the current.

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#10

Got it thank you. And just to confirm my understanding, the number in parallel only affects capacity of battery (and by extension range of the esk8), is that right?

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#11

Correct. If your cells are 3,200mah and you add one group in parallel you double the capacity to 6,400mah.

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#12

Adding to what kavic said, It also gives more current as well. If a battery gave 15A, doing a 2p will give you 30A, 3p will be 45A, etc. Easier to deal with than having high voltage on an esk8 tbh.

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#13

Sounds good, thank you for all the advice to both of you!

One final question I had: for the motors, I have the option of customizing the KV before order, anywhere from 120-220 KV. If I went with a 12S or a 13S battery pack, do you have any suggestions for what I should go with? I know I can likely just gear (or more likely, chain) it down, but wanted to see if there were any opinions on this matter as well.

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#14

The higher the Kv, the faster you go, but the trade off is low torque. The lower the Kv, the higher the torque, but your speed may suffer. The balanced one I know so far is between 190 and 220 kv.

That’s my go to. Your choice depends on your living conditions. Flat land? Hills? That will determine what you get. That will be on you entirely.

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