Why is there no on/off switch integrated in a VESC

ESK8 Electronics
1

Hey guys,

after buying a Lou board I want to replace the ESC with a Focbox I have around. What bothers me though is that in order to turn the VESC off/on I have to use an AntiSpark switch somewhere in my circuit. Why is that though? Why doesn’t the VESC have a small switch that can turn the power supply for its “brain” components off or on? The current can’t be high so even the tiniest switch would suffice. There should be no need for an AS when I only rarely disconnect the battery. The Lou even has a push to wake the ESC function - that is awesome and eliminates an additional part.

What i also don’t understand is why even a redesign of VESC6 like uses additional FETs just for the sake of turning the VESC on and off - is that really necessary?

Well I hope someone can help me understand - there is probably a reason and I really want to know.

2 Likes
2

What? you mean a switch to the MCU only?.. you want constant voltage delivery onto the input?. This sentence doesnt make any sense to me.

That redesign doesn’t have anything to do with the original HW verision. I cant see any Fets for switching on that card?. The mechanical switch on the board is for different voltage on the hall sensor input.

3

We never saw the bottom and so it’s hard to say for sure, but it appears they did add FETs for power switching, the three devices under www.flipsky.net on the PCB

4

Why shouldn’t there be a constant voltage on the “input” as long as any power to the brain components is switched off? Does that damage anything? What will be damaged?

Hm? the three fets on top close to the XT-connector are just an AS - the fets for the motor are on the opposite side (there are 12 of them - see post below). The switch is supposed to be wired and not pictured.

5

yes we did see the bottom

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Introducing a constant voltage-source on the drain?.. Not sure how big the leakage and what dissipation and wear that equals to, or what even happens when you roll the board in off mode with live battery wires, but no. you want as good isolation as possible in Power applications. Especially in off-mode. I can’t think of any obvious benefits to this proposal.

8

I don’t understand :frowning: Why would it be worse than having the AS FETs exposed to the constant voltage? There must be a way to isolate the brain components so that they don’t see any voltage when off no?

9

The main purpose of the AS is to limit inrush currents. You wont have that function at all without altering the VESC. The AS also provides a safe Power of stage where the VESC is physically disconnected from the battery. You wont have that either.

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i do not think that the lou board handles 2500w strong batteries=huge currents=boom in shitty parts

11

A normal AS can’t handle 2500W. 50A continuous is the max any AS can handle.

12

I was talking about ESCs with integrated “AS” or an on off switch

13

Why would I have inrush currents when the capacitor stays connected to the battery?

14

Doesn’t matter though no? 2500W is a crazy amount of power and even VESC based systems can’t handle that with the standard AS we have today.

BTW: When talking AS I do not mean loop keys - that’s a different story.

15

Crazy? Idk man my current build I’m working on is 4400 watts at peak power draw. There are 5055 motors that can easily draw 2000 watts.

16

If your system would draw 4400W continuously do you know how fast your battery would be empty? With a 10S4P of 30Q cells you have 12Ah*36V=432Wh --> 432Wh/4400W=not even 6 minutes. Your components would melt by the way - don’t believe marketing terms! Just because a motor can draw such power it does not mean you are actually ever using it. The VESC can’t handle it and a normal battery can’t handle it. And peak usage is an irrelevant number and does not mean anything.

1 Like
17

Is BMS with switch an alternative solution to Anti-Spark Switch?

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18

it’s even bigger than an AS so no. I want to simplify not add even more complexity. I usually don’t use BMSs in my builds - I find them unnecessary.

19

I’m talking about peak power draw.

Also, 2500 watts of battery current is easily within the realm of possibility of exceeding. That’s 50 amps from a 50 volt battery.

I’m not just believing in marketing terms. My last build using a 10S2P lipo had peaks of 60 A. I opted to use a loop key because I was worried about longevity of an antispark.

And regarding why vesc’s don’t have integrated antisparks: A VESC is designed for DIY pick and choose parts. To appeal to more users it’s not included. If a user does not want to use an antispark, they simply don’t have to. Adding an integrated antisparks to a VESC is is just going to take up more size, about as much as an external antispark would be anyways.

A business isn’t going to go that route, because it’s simply not appealing to consumers. Adding more components that can fail onto one PCB is going to cost DIYers more in the long run, as your repair costs and likelihood of failiure go up.

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As I said peak is meaningless, especially not when talking about the AS situation.

Also i don’t believe that to be the reasons why the VESC has no AS built in.

I’d love to hear what actual electronics pros like @JohnnyMeduse or @SimosMCmuffin have to say on this topic.

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Im an EE by occupation :zipper_mouth_face: You seem hard to convince however. Not sure how I can explain things in an easier manner.