I'm an Electrical Engineering student still new to power systems. I'm working on a project that uses a 24V and 200Ah battery bank made up of 4 AGM lead acid batteries. The batteries are supplying four brushed DC motors, the motor drivers, various sensors, and two Arduino Megas. Maximum continuous current draw from the system will be about 80A total. I need a safe way to create a battery disconnect for the system that is controlled by a large push button that is remote from the battery bank.

I've been looking at contacts and relays as well as a key actuator disconnect switch like one on McMaster-Carr (item # 7110K42). It is rated for 100A at 12VDC. I should mention that the product is on a tight budget which is why this is an option as opposed to a contactor.

I am wondering if it is possible to use two of the key actuator switches, since the battery bank is composed of four 100Ah 12V batteries, and an actuator switch could be placed somewhere in the battery bank that could disconnect power to the whole system safely.

I am worried about the specific placement and also potential arcing during switching. I'm getting buried in research and am just hoping for a little input or guidance on which direction to continue research and tips on how to proceed.

Much thanks.


1 Answer 1


Unless your load can also be split in half, I would not recommend splitting the supply in half by using two switches. I know this suggestion is going to be crude and some people would definitely take issue with it, but I've done it myself in a pinch (to control a 24VDC 2hp motor @ 60+amps). I just took a DC circuit breaker that I found on an old solar charge controller setup. They don't cost too much and also offer your over-current protection. See solar suppliers (such as https://www.wholesalesolar.com/circuit-breakers) for a selection of high current DC breakers, though you can probably find cheaper ones that aren't for a specific market like solar.

  • \$\begingroup\$ Would any other circuitry or components be needed along with the circuit breaker? Most of what I'm finding on wiring of circuit breakers is pertaining to AC in a residential use. This does look like a cost effective solution and may work, so thanks! \$\endgroup\$
    – egcfsu.13
    Commented Jul 13, 2017 at 21:05
  • \$\begingroup\$ An appropriately sized circuit breaker should be stand-alone. It's not going to give you over-voltage or under-voltage protection, but that's not so much an issue with lead acid batteries. And the breaker gives you your over-current protection, which you won't get with a simple switch. Do take into account the amount of surge current that is present in motor applications (could push you well above 80A) - you mentioned motor drivers in the mix, but you can still get a surge. \$\endgroup\$
    – Will
    Commented Jul 14, 2017 at 21:21

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