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Topic: failing to make an E switch with mosfets... (Read 528 times) previous topic - next topic

ted

This is for 24V may work for 50V, to be safe increase r3 to 1k and test it.


MikeLemon

Hi,

What is your output connected to?

Where is the 50.4V from, what device?

Can you tell us the application of all this?

Thanks.. Tom... :)

Well so the voltage comes from a 12S liion battery connected to 2 bldc esc's to drive electric skateboard motors

TomGeorge

Hi,
Well so the voltage comes from a 12S liion battery connected to 2 bldc esc's to drive electric skateboard motors
So you will be ground switching power to the ESC's, what is controlling the speed of the ESCs?
Because of your load being an ESC with some controlling circuitry attached, you may have to high side switch the ESC On and OFF.
Thanks.. Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

MikeLemon

Hi,So you will be ground switching power to the ESC's, what is controlling the speed of the ESCs?
Because of your load being an ESC with some controlling circuitry attached, you may have to high side switch the ESC On and OFF.
Thanks.. Tom... :)
No the motors are just general loads, I want to make that e switch to contain the whole system and turn it on and off with a small little switch sins there are not alot of switches that can handle that that much current that are of a reasonabke size.

Wawa

#19
May 21, 2018, 12:04 am Last Edit: May 21, 2018, 12:09 am by Wawa
Did you Google "battery isolation switch".
The ones with the red key are common as dogshit.
Just don't switch them on or off when the motor is running.
Leo..

TomGeorge

#20
May 21, 2018, 12:19 am Last Edit: May 21, 2018, 12:25 am by TomGeorge
Hi,
You are calling it an "E Switch" is that an EMERGENCY SWITCH?

If so then forget about any electronics in the "E Switch" circuit, check what you can get in a proper switch and if needed a relay.

Any EM-STOP I fit is purely mechanical and in the live/positive supply line.

If you wish to isolate the entire system, fine.
BUT
You must isolate the positive of the supply, in your configuration, if you isolate gnd, you MAY disable all features, BUT the circuit is still at full positive battery potential with respect to gnd. 

50Vdc shock is not pleasant and can be capable of 1mA needed to cause lethal harm.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

MikeLemon

Hi,
You are calling it an "E Switch" is that an EMERGENCY SWITCH?

If so then forget about any electronics in the "E Switch" circuit, check what you can get in a proper switch and if needed a relay.

Any EM-STOP I fit is purely mechanical and in the live/positive supply line.

If you wish to isolate the entire system, fine.
BUT
You must isolate the positive of the supply, in your configuration, if you isolate gnd, you MAY disable all features, BUT the circuit is still at full positive battery potential with respect to gnd.

50Vdc shock is not pleasant and can be capable of 1mA needed to cause lethal harm.

Tom... :)
It's just going to be used to turn the system on and off externally from a small switch.

I want to predict millions of cycles maintenance free for it and it needs to be super reliable.

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