relay control of 40A peak motor - beefcake?

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lingon27
Posts: 1
Joined: Fri May 11, 2018 9:37 am

relay control of 40A peak motor - beefcake?

Post by lingon27 » Fri May 11, 2018 10:12 am

I am working on an automatic door opener/closer that uses:
a car window motor
12v car battery
2 stop sensors (just mechanical switches)
arduino uno r3
motor driver shield (old version DEV-09815) running 2 relays.

The inrush current for when the motor starts is about 40A, steady state when moving is 7A. It will run twice a day for 3 seconds unless I'm testing it. (I have a circuit diagram but getting it uploaded to a link hasn't happened yet.) One side of the motor goes to NO (supply 12v) or NC (ground) of one relay. So the motor normally is grounded, then depending on which relay switches the motor will get 12v on one side which chooses direction. That means both the NO and the NC need to be able to handle the 40A peak current, right?

I would love to use a pre-built relay shield with the diodes, etc, all in there so I don't have to design/build my own. But I can't seem to find anything that can deal with such high current. The beefcake relay KIT-13815 only does 20A/10A. Is it correct that I shouldn't use that for more than 10A, even for a few milliseconds? Where can I get the peak current info vs steady-state limits for the beefcake relay board?

Thanks.

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