Diy anti spark switch?

Hey guys I was thinking about the antispark switch and I thought I could implement it in a cheaper way,

Puting a 3 state switch, with a resistor on the intermediate position to avoid the spark

Do you think it will work?
The switch will be high current supported of course…

If so, what resistor should I use?

And for example, this 3-state 50A toggle switch from amazon for 9$:

    1. I measured the resistance in a cheep multimeter of an existing XT90S as 5.6 ohms
    1. in your drawing you show a 3 pole switch, if the switch is left in position 2 for more than a moment the resistor will blow
    1. The switch you linked is a SPST switch
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Interesting idea, it might work. Get rid of the fuse (put that on the charge port)

I’d try a 10 ohm 5 watt resistor to start maybe like this

See if you destroy that or if it charges fast enough to mitigate spark, adjust the values from there. Maybe go down to 4.7Ω

how you you make the Ω symbol? ascii code?

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I always look up “ohm” on wikipedia and copy it from the text there :laughing:


there is always an easy way… thanks!!!

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^following on from this, you want a SPDT switch

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in your drawing you show a 3 pole switch, if the switch is left in position 2 for more than a moment the resistor will blow

if you can’t find a spring-loaded switch that is either in position 1 or 3, and only passes momentarily thru position 2, you are doomed to have failures

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More trouble than what it’s worth.

Wait for haggybaord antisparks to come out, they will have fully effective smart functions (no push button needed) and be very attractively priced.

Yes they ARE coming out, I can’t say exactly when until the testers are ready to write their reviews.


Is there anything haggyboard cant do? Hey HB dual 6 vesc please.

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Think that may exist

Its gigantic though.


This is my relay-based antispark.
Slowly charges capacitors when button is pressed, capacitor’s voltage turns on transistor that energizes the relay.
But if switch is not toggled, relay does not turn on

Thanks for the tips and measurement!
Why would the resistor blow? Once the capacitors are fully charged (a matter of few miliseconds) the current goes to zero, isn’t it? The resistor only limits the initial infinity current.

Theoretically, I can leave it all at state 2, even drive with it, but the fuse (I was thinking 10A?)
Will blow once driving so the resistor wouldn’t blow either that way…

Correct me if I’m wrong

About the switch, what is SPST? I really just put the chrapest one I found with 3 states… I have no idea what is it

Please elaborate

Thank you!
Why get rid of the fuse?
I was thinking about it to protect it from over current on that state, in case state 2 is stuck or helded too long

I doubt I’ll find one, the hard part was finding something cheap but also heavy duty for high current…

I really don’t understand why it matters
What happens if you leave it on state 2 for long period of time

Once capacitors are loaded no current is flowing unless I run the motors

using your terminology not mine… the switch you posted has only two states not 3 (thus SPST) single pull single throw, you need a SPDT single pull double throw switch to get 3 states…

The resistor will heat (really hot) up when you allow full current to flow thru it other than momentarily…

look at an XT90S that has a resistor in part of the plug that allows current to pass thru MOMENTARILY as you engage the plug… if you leave it plugged in only partially the heat of the resistor will melt the connector…

follow me?


Maybe I’ll put something temporary for now and when it arrives I’ll upgrade to that, thanks! Is there any link to follow that?

What exactly do I see?

He said he used flipsky anti spark switch