Dear community
I want to use a DC device that draws from a 42V battery, 15 amps of current in its maximum functionality. All arduino relay modules that i know of, they work at 10A, 30 VDC. My question is:
If my device draws 5 amps, at 42 V, will it be a problem for the relay? I cannot fully understand how DC voltage is related.
Those small relays are only rated to 28 or 30 volts DC and 5 Amps for inductive loads. What are you switching with the relay?
There is a 30 Amp model but switching high current DC with cheap relays is risky.
The problem with switching DC with a mechanical contact is that when you interrupt DC you get an arc. Unlike AC, DC does not turn itself off many times per second, and above about 30VDC the arc tends not to go out, but carries on with the current flowing through the resulting plasma. This quickly destroys the contacts. Relays to switch DC above about 30V are expensive as they have to deal with this. I suggest you use a MOSFET instead.