## 14S VESC ?

General topics and discussions about the VESC and its development.
scienceworks
Posts: 29
Joined: 27 Mar 2016, 16:27

### Re: 14S VESC ?

but then you will have shitty acceleration and maybe not even enough power to get to topspeed.

im not into skateboards, but i know that most use motors lower than 200kv AND a reduction beltdrive.

Hummie
Posts: 110
Joined: 10 May 2016, 04:05

### Re: 14S VESC ?

but if I upped the motor amp limit while using the higher 200kv I should get the same torque in theory. I should've changed the motor amp limit. With the 60 limit the lower kv go up hills faster.

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

### Re: 14S VESC ?

YOU ARE already running at the 60A limit. Even if your battery current measurement shows 25A.

You could increase that to 120A. This will increase the losses in your VESC by a factor of four. As most people report "about 50A max", setting the limit at 60 and then going uphill at full throttle is asking for trouble. But so far you've been lucky.

As long as your VESCs don't get too hot, you can increase the amps. Up to about 240A according to the datasheet. So if you have exceptionally good cooling, you can probably get a bit higher than 60A.

The inverse of the "kV" is the torque constant. It defines how much torque you get for a given number of amps. So your torque constant for the 100kV motor is about 0.1 and the torque constant for the other is 0.05. So the 200kV motor requires even MORE amps to produce the same torque. Again, you're going past the safe limit for the VESC.

Actually you need 50 or 70kV motors, or you need to change the gearing a bit. use 1.4 to 1.5 times less teeth on the motor gear. As that one is probably already at the minimum you need to increase the other one.

Hummie
Posts: 110
Joined: 10 May 2016, 04:05

### Re: 14S VESC ?

rew wrote:As long as your VESCs don't get too hot, you can increase the amps. Up to about 240A according to the datasheet. So if you have exceptionally good cooling, you can probably get a bit higher than 60A.

ok I can simply check the temp and find the amp limit

The inverse of the "kV" is the torque constant. It defines how much torque you get for a given number of amps. So your torque constant for the 100kV motor is about 0.1 and the torque constant for the other is 0.05. So the 200kV motor requires even MORE amps to produce the same torque. Again, you're going past the safe limit for the VESC.

I forget how many turns of wire are on the 200kv but if there are half the turns as are on the 100kv I would need double the amps put into the 200kv to get the same torque right?

Actually you need 50 or 70kV motors, or you need to change the gearing a bit. use 1.4 to 1.5 times less teeth on the motor gear. As that one is probably already at the minimum you need to increase the other one.

these are 80mm diameter hub motors and so I'm limited to choosing the kv alone. At 80kv I hit maybe 26mph and can fly up hills, the 100kv have a max speed of about 33mph and don't get up hills as fast. But in thinking of just increasing the motor amp limit and watching the vesc temp and in theory it should get up the hill just as fast. And the motor should get just as hot. (The higher kv are getting hotter and they're slower but I suspect because they're under load longer to get to the top) Except the vesc could get hot. So far it only gets warm at most. Do I need to be concerned about any other components getting hot other than the fets as I'm planning to pot the vescs in resin?

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

### Re: 14S VESC ?

rew wrote: As most people report "about 50A max", setting the limit at 60 and then going uphill at full throttle is asking for trouble.

Hummie
Posts: 110
Joined: 10 May 2016, 04:05

### Re: 14S VESC ?

Damn I'm either over the limit if I listen to the max 50 rule but I'm doing fine if I put my finger up to it. I'll have to ride again soon and really check the vescs temp maybe all the seperate components. I'd like to believe that if nothing gets hot I don't have to worry, and stay at 60 amps. I have good passing wind but no heatsinks on the fets as I'd planned , but they never get hot.

Hummie
Posts: 110
Joined: 10 May 2016, 04:05

### Re: 14S VESC ?

What are the safe limits or where could I find them? I've been using the default settings for most

jaroslavnovotny
Posts: 49
Joined: 16 Feb 2016, 13:10

### Re: 14S VESC ?

What are the safe limits or where could I find them?

This thread is starting to be fun

rew
Posts: 943
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

### Re: 14S VESC ?

Hummie wrote:What are the safe limits or where could I find them? I've been using the default settings for most

A safe limit is that you don't hurt your finger if you press it against the FETs right after riding up the hill.

joe90
Posts: 49
Joined: 15 Dec 2015, 16:52

### Re: 14S VESC ?

You can program temperature safety limit.

Base settings:
It start at 80C to ramp down current and stop at 100C
if you keep it like this it will protect your esc.
Benjamin put those limits and tested them.

So if you averheat esc it will self protect.

My setup is good for 25A batt current continious with some air cooling no heat sink
I run 90A phase current
I have 50A batt peak current

At 35A sustained battery current I overheat after 90 seconds

On 12S you can get 1000W continious and 2000w peak for a few seconds
Michel Cote
Twin v4.7 + SK3 6374 149KV
Bicycle
2500W peak/unit on 12S