Minimum specs for precharge switch?

[johnxsi]

I'm wanting to put in a momentary button switch to control the precharge circuit and was wondering if there are any minimum specs for the switch?

I'm running a 16S 6P A123 pack, so do I need a switch that can handle 52V/15A? Switch ratings all appear to be contiuous, not peak.

Thanks!

 

[jamo96]

It all depends on the value of resistor you choose. Higher value = lower current and hold switch for longer, Lower value = higher current/hold switch for shorter period.

I am not sure what everyone is using out there as pre charge resistors. I just built myself a inrush suppression circuit with 4 x 4110 FETS, 2 resistors and a capacitor. It fits inside my 12 FET controller. No sparks. No button or resistor to forget (though prob wasting a hopefully small sum of watts whenever running)

 

[wesnewell]

You don't need a switch for a precharge resistor, but if you want one, any mini toggle switch will work. Once you hook up the mains, all current will flow through it.

 

[nicobie]

I've been running a cheap one from radio shack with a 300 ohm resistor on my 24s system with no problems.

 

[johnxsi]

Cool, thanks guys!

 

[CanadianWinters]

I used a 380 Ohm 3.75W resistor that I had sitting in my little lab.

These power resistors can also be "recycled" from ATX power supply or old CRT monitor electronic boards.

It works great on my setup: 36V Li-ion 24Ah battery & ku123 30A controller.

This is what I did (with videos): http://jacklithium.wordpress.com/2012/07/31/anti-spark-system-inrush-current-limiter/

 

[wavezz2k]

From this thread, thanks BTW, I added a slight twist.

I was planning to use a 40a relay, and went ahead and added the precharge with a momentary pushbutton. My switches are weatherproof enclosed, and using a relay, I'm not directly switching the mains. So, No Zap. Frankly, don't like the idea of snapping 200 amps 70 v in a drizzle, which is common here in winters.

The relay is $5, readily available, and is only about 1 inch cube. Waterproof rockers are from radioshack, $3.

Still doing bench tests on this , but gives the idea with a slight twist. Cheers.

 

[dnmun]

why not use mosfets for the switch like jeremy?