Switch for high DC current and voltage?

Hey guys,

I'm building a dummy load battery discharger from 10 1500w 5ohm resistors.
This device will carry sometimes 150A on about 80V and sometimes 100V (not for discharge but more like a short stress test).

The problem is, when you connect the last wire to close a circuit then at these amps there is a giant spark that can really create a surge that will break any connector in half when it first touches before it's sitted all the way in.

I need a switch like those 200A 12V car DC trip switches but that will handle a much higher voltage.
Is there such a thing?

Use a inrush limiter instead.

You can either buy one, or make one out of a negative thermal correlation thermisistor. The resistance starts high to limit current, as it gets hot, it lets more power through. Connect it first, connect main load second then disconnect the NTC.

Sunder said:

Use a inrush limiter instead.

You can either buy one, or make one out of a negative thermal correlation thermisistor. The resistance starts high to limit current, as it gets hot, it lets more power through. Connect it first, connect main load second then disconnect the NTC.

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Can I buy this ready to go?
I don't think I have the components nor knowledge to build one myself

The premade ones are for lower voltages, e.g:

https://hobbyking.com/en_us/xt90-s-anti-spark-connector-2pairs-bag.html?___store=en_us

For such high voltages, i suspect you'd need to build it yourself, but I'd be happy to be proven wrong. I have only ever made one in my life so I am not an expert.

It was just an NTC in line with a small, easy to connect molex. Could do it with any connector. Only thing you need to work out is the size and resistance of the thermisistor.

How would one build a switch in order to switch between a 36V battery and a 48V battery, knowing to change the controllers LVC which is easy to do on the fly. I have been doing it manually with wires coming out of the controller.

ON-ON toggle - https://www.be-electronics.com/product_p/41-253-1.htm

6A @ 125VAC 4PDT on-on

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If it fuses together on the inrush current even with the ASXT90's then I will know to buy a higher amp toggle switch.
I may just have one operation that changes the battery, plus changes the lvc of the controller, so 5PDT or 6PDT.

Personally I recommend a triple throw switch. You can get one that actually has terminals for the center position, or a center-off, but in either case you don't use the center position. This gives you a complete "off" position, between the two packs, and ensures you cannot accidentally make-before-break due to arcing or switch design (which would short the two packs together).


You also don't need to switch the negatives--all the grounds can be tied together, and simply switch the positives.

So you can use a 1P3T-center-off, which would be around 1/4 the size. (possibly important since you'll need a largish switch to handle the battery current).

Sometimes they're called ON-ON-ON or ON-OFF-ON rather than 1P3T.



I haven't looked thru what's here
https://www.mouser.com/Electromechanical/Switches/Toggle-Switches/_/N-5g2j?keyword=1P3T
but that's once possible source.

Some others:

https://www.google.com/search?q=1P3T-center-off++%2Btoggle+-slide+-rocker&btnG=Search&num=100&newwindow=1


Keep in mind you want a DC-rated switch; the AC-only-rated ones may have a smaller gap between contacts so any arc that does start in an AC-switch used on DC may not extinguish, and continue arcing across even once it's switched over to another contact, if there was enough current flow to start with. (another reason to use an ON-OFF-ON or 3T-center-off version).