Relay size for wiring aux lights to high-beam power?

I am about to embark on trying to mount up some Rigid light pods on my Sprinter and my plan is to use a relay with the control power coming off of the power wire to the high beams and the supply power for the lights coming off the aux battery under the hood.

This has been discussed before but one piece of the puzzle I just cannot find: Any idea how low I need to have the coil current on the relay so it will not mess with the Sprinter electrical system and cause the headlight out warning light to come on when I tap in to the high-beam power wire? Basically what relay should I use? There are 1 zillion options out there. I can find a good Panasonic relay with a coil current as low as 67 mA for like $5 (https://www.digikey.com/product-detail/en/panasonic-electric-works/ACV31012/255-5270-ND/644633), or I can get an ETA solid state relay with a coil current of as low as 10 mA for more like $42 (https://www.digikey.com/product-detail/en/e-t-a/ESR10-NC2A4HB-00-D1-17A/302-1466-ND/6490745)

I will spend the money if that is what is needed, but if it is overkill I will just go with the Panasonic one. Any experts out there have any advice? Am I approaching this wrong?

Thanks in advance,
JR
 

autostaretx

Erratic Member
If you're leaving the original high beams still connected, then a 67 ma 12 v relay should be invisible to the Sprinter.
That's less than one watt. (as the specs say: 800 ma, 180 ohms)

The normal H1 or H7 lamps are 55 watts, so that's over 4.6 amps that it's expecting to see ... which is about 2.6 ohms.
(there are factors such as bulb in-rush, etc, but for this those numbers will suffice)

It should work fine ... i might be temped to go for "overkill" and use a 30-amp rated set of contacts.
(not knowing what your light bar characteristics are)

--dick
 
Thanks autostaretx, I am going to mount 2 light pods on the hood using the Van Compass mounts. Each light pod is rated for 3.5 amps, so 7 amps total. I figured a relay rated for 20 amps would be a sufficient safety factor, however a 30 or 35 amp relay is basically the same price. I may just get a higher-capacity relay in case I use it for a 20-inch light bar some day in the future. Thanks for your Insight, much appreciated.
 

Aqua Puttana

Poly - Thread Finder
To my knowledge the lamp monitor circuits look for low or no current. They aren't designed to look for higher current. Any relay coil will be fine.

My data is that headlamp bulbs come in varying power configurations. Many owners change over to higher wattage lamps than OEM without the monitors noticing.

:cheers: vic
 

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