Motor/ESC brakes under hard acceleration

So my replacement pulleys from johnny arrived on Thursday and I installed them and the new 90mm wheels today, then took the board out for a test ride. First thing I noticed, 90mm is fantastic compared to ~60 :stuck_out_tongue: Second, I noticed that now that I’m using a 15mm belt and pulleys instead of the paltry 9mm, I get 0 belt slippage no matter how hard I accelerate or brake. Woo!

Unfortunately I’m facing a strange issue. When I accelerate hard the board instantly throws me off forwards. It’s not just cutting the power, it’s actively braking. Except it’s not a normal brake. It doesn’t squeal like it normally would while braking (it’s a 150A X-Car esc) and it makes a different sort of noise. At first I thought it was the receiver cutting out due to power brownouts, so I put a 220uf cap on the BEC from the ESC. Tested again, still threw me off. It’s very consistent and I can replicate every time.

So I’m not sure what it could be. It doesn’t sound like the ESC is braking, but it feels like it is. Sort of. I wondered if maybe it could be motor timing, but I don’t know anything about that so I don’t know where to start.

I have the exact same issue with my X-Car Beast… :sob:

Been trying to solve it for months but without any success.

Does it sound and look like this? YT link: X - Car Braking during acceleration

You could be hitting the ERPM limit of your ESC and it is braking to avoid damaging itself. What is the kv of your motor and how many cells is your battery? Although I have no idea what the ERPM limit of that ESC is though, you’ll have to check to see if you’re exceeding it

Check for faults (DRV), I had the same issue but I could kinda about it by accelerating very slowly.

@TeslaAlex Yes, that’s exactly it! Dang, maybe I’ll have to buy a vesc after all :confused:

Except that it does that only if I accelerate hard. If I accelerate more gently I can reach full speed with no issues.

It sounds nothing like braking normally.

These are X-Car ESCs, not vescs, so checking for faults isn’t a thing.

1 Like

Yea, I’ll will definetly throw away that garbage rc ESC and pick up a FOCBOx on the upcoming sale. Im tired of things not working properly, should have gone the VESC route like everyone said, but I was too greedy… :grin:

@Clonkex and @TeslaAlex I have this same esc and I might know what’s wrong. This is just a theory but could you be drawing to much current and voltage sag is making you hit the low voltage? Although from the sound it doesn’t sound like it

I have done several tests with a multimeter and neither Amp draw or voltage sag seems to be a problem.

My specs: 2x 5000mah 3s 20c zippy in series X - car beast 120a 5060 NTM Propdrive 270kv 12/36 gearing

Hmm maybe temp shut off? Do you need to restart the board after?

Nope, no need to restart after it shuts off.

The ESC has a specific light (blue led blinking) for temp shutoff and it doesnt light up that way.

Jeez I don’t know what it could be then. Did you set the motor timing to high and set all the settings? What remote are you using?

I haven’t tried changing the motor timing yet but it’s my next troubleshooting step.

Are you able to reach your top speed with it on the normal setting? When I go mine I could only go half throttle until I changed it

Yea I reach the top speed when accelerating slowly.

Im using this remote: Link

I have the programming card and have tried all possible settings for motor timing, low voltage shutoff etc… This is such a wierd problem… :confused:

Same as Tesla, I can reach top speed easily, I just can’t accelerate too hard.

What remote are you using? The only thing I have not tested yet is to change remote

@Clonkex @TeslaAlex I have know idea why it doesn’t work mine has worked perfectly since I got it although I don’t really do hard acceleration because I will fall off since my deck is so small

It’s kind of unpleasant to test this problem too since it involves accelerating hard with the intention of having the board throw you off violently :stuck_out_tongue:

just scrap it and get a focbox!

1 Like

Have a FVT car esc on my board and when i accelerate hard it cuts off, breaks a little and just coasts for like one sec, after that i have full control again. Powering up a hill and pulling the trigger to accelerate has a similar effect, it just cuts off the power and sometimes puts me in its slow mode to protect itself. I ran a 260 kv motor, i have a 190 kv coming in the mail. It felt to me like the esc couldnt keep up with detecting the rotor position, and just freaked out and decided to cut power to slow down. Maybe i was using too much power, when accelerating and keeping my hand close to the esc it started blowing warm/hot air out of its heatsink. But the esc has always put me in limp mode after spirited riding up a hill, so i guess the issue isnt related to the power draw. Will let you know how a 190 kv works out, also will play with the setting and the software.

1 Like