Unfortunately, since both of the VESCs won’t turn on, I can’t access photos of the config. Here are some of the important settings we changed. Let me know if you have any further insights, but everything we did in the programming should be pretty standard.
Motor current: 65A, -65A braking (both sides)
Battery current: 35A , -12A regen (both sides)
ERPM limit: 80000, -80000
Limit duty cycle current limit start to 85%
It could just be a bad batch of DRV chips, but since its happened twice I think I’m going to get a different VESC (Stormcore) and adjust my build to reduce future risk. Nothing against the Unity per se.
Right. Unfortunately, I can’t quite place the cause at this point. Reducing the length on the battery leads is probably going to happen though. I can change orientation so the wires can be shortened by a foot and a half. I’m also going to get different wires as I can’t exactly vouch for the quality of what’s in there right now…
How would I go about adding capacitance? At this point, I’m going to do what I can within reason to reduce any risk of future damage.
Haha I’m able to get a refund on it right now. I think I’m gonna go with the Stormcore as I can afford to do so and I don’t need to risk another Unity blowout.
I’m new to esk8 so I’m not super familiar with everything despite being an engineer and having decent intuition. So setting the max ERPM is limiting what exactly? I understand what you’re saying for setting the duty cycle, but why shouldn’t I change the max ERPM numbers? Again, my friend is pretty much guiding me through this process and he was directing me to set it to 80000 based on his experience.
That’s great. Keep both wires next to each other. Twisting them together along their length is even better.
Not to sound flippant but you do that by buying capacitors.
The ESC has some already there so you could just buy another set of equally rated ones but installing them requires electronics knowledge, soldering experience, and a good awareness of the safety precautions you need to take. Unless you have done things like this many times before I recommend not trying it.
If you’re getting a Stormcore just do the wire shortening thing.
Another consideration…too much capacitance can burn out anti-spark switches that aren’t rated to handle it.
Duh. Nobody would ever guess that I took an electrical engineering course at my university just a few months ago.
Given everyone’s advice, I think shortening the wire will be sufficient. I also saw there are a couple more capacitors in the Stormcore (which is what you’re implying I think).
Setting the electrical rotational speed above (or below) which the ESC does not send/receive current to/from the motor.
Because each ESC has defaults set by the manufacturer, and for esk8 it’s best to leave them alone. If you were driving a propeller or something, you may opt to lower them in certain circumstances. For esk8, all it does is “cut brakes (& throttle) above X speed”. It’s not limiting the motor speed.
He probably hasn’t hit his limit yet and doesn’t understand what it does. It’s not limiting the motor speed. It’s limiting throttle and brake output. Use duty cycle to limit the motor speed.
And yet another consideration is that if the extra capacitance is on the battery side of the antispark switch, it won’t [accelerate the process to] burn out the switch but it will “leak” battery current while it’s turned off and can very slowly drain the battery, possibly destroying the battery if left to its own devices for too long.
Why is it that its always seem to be the 8301 that blows and not the 8303 on the unities?
Both DRVs runs identical settings but the 5V is taken from the 8301… coincidence?
Is the buck converter the weakest link?
Overloading/ shorting the 5v rail?
He actually sells boards. Off the top of my head, I think he has three unities of varying ages. However, he has sold 70+ unities in boards including recent sales in the last six months. Both of the unities I popped were brand new.
Agreed. Two in a row could be bad ESC to motor connections, motor phase wires shorting against the motor or mount, partially shorted windings, corroded sensor wires, voltage spikes due to long battery cables, etc.
