Hi guys, long time reader but first time poster. I’m building a 4 wheel drive vehicle with VESC based controllers, and I’m looking for an anti spark type switch to power off the VESC so I don’t have to physically unplug the connectors. I’m going to put each individual VESC on a separate switch, so I need high side switching. The flipsky smart enhanced switch seems like a good option, however I would really like to NOT have roll to start. I would rather be able to shut down one or more controllers if necessary. Does anyone know if such a switch exists?
Be careful with the separate switches, some old vesc(maybe 4.10? not sure but I’m sure someone will know it) was blowing up its CAN chip if it was connected to another vesc which was powered on but the first unit was not. I think this is not an issue anymore with VESC6 designs.
I dont know if this anti spark exist’s but as an alternative you could do some Metr profiles where your front motors max duty cycle is 0%( Im actually not sure this would do what I want to achive so some second opinion would be more than welcome )
This way you would not turn off the controller phisically but you would mitigate the real power drains which are the motors.
if you have CAN connecting each esc to eachother with 5V, you only need 1 switch to turn all of them on
i’m not sure how to solve your question, just noting something worth me tioning
Maker x has a pretty tidy solution for you I think @a.smith. But as others have been saying, if your vescs are all connected via CAN, you should only really need one.
From what I understand, the vesc6 revisions don’t have this issue. Also, I think the problem may arise from low side switching anyway?
Thanks for that. It looks like it might be just the ticket. Do you happen to know if those switch the positive or negative leg?
You can prevent the CAN connection from powering up additional ESCs by leaving the 5V pin disconnected.
However, you cannot stop the motor spinning from turning on the ESC, it will do that from BEMF alone, even if there is no battery or antispark switch at all. The difference here is whether the ESC turns back off when the motor stops spinning. If you have another ESC spinning a different motor, and they are connected physically through some means (such as both connected mechanically to the street with wheels) then you can’t realistically have one ESC remain off. Unless you disconnect the motor from the ESC, which opens a whole 'nother can worms.
I feel like what you want is to control some sort of throttle signal to the unwanted ESCs and not actually leave them powered down.
I tried to power up one of the ESCs I have (a flipsky 6.7 mini) regeneratively with no battery attached using a drill on the motor, but I didn’t have any results. Could it be that it just wasn’t spinning fast enough?
To explain what I’m doing a bit better, I’m driving 4 wheels separately using a micro controller talking to each ESC over CAN. I’m not using CAN forwarding. My idea for individually powering on / off each ESC was to isolate one or more in case of a mechanical or electrical fault and for testing purposes. I could probably settle for a 0A idle current condition over CAN which is easy to implement, but I was hoping for a hard power off option to disconnect the ESC from the power bus entirely.
It seems these FSESC 6.7s don’t generate any power when they’re off. I tried spinning up a motor again with no battery connected, and there’s no resistance at all - like the mosfets are open.
They are open, but they typically have body diodes.
Does that mean it should be feeding the ESC some power as long as the motor’s generated voltage is above the forward voltage of the body diode? So probably like 1V.
I’m trying to wrap my head around why I’m not getting the expected behavior of the ESC powering up when spinning the motor. It makes sense that the mosfets can’t prevent reverse current, so why isn’t it happening?
If the ESC is powered up and the current is set to 0, it can freewheel all day and produce no power. So is it possible to reliably achieve that when powered down, or do you need to pull the mosfets into an open state?
I guess the mosfets on this ESC just happen to be open and not conducting, but some stray voltage could potentially change that and cause a braking effect.
What ESC is it?
It’s Flipsky FSESC Mini 6.7