View Full Version : Relay question

28 February 2011, 1955
I've got a standard automotive relay that I'm using to switch on a warning light to show that my contactor is active. I go from the engine kill switch to the coil of this relay, then to the coil of the relay that switches on my controller, then to ground. Trouble is I'm getting a 6V drop across this coil and it's not strong enough to close the contacts without a tap. It also means the downstream coil is also underpowered and also needs a tap to help it close. I was using one of the original bike relays yesterday and it was working fine, but I just checked it again and it has a 5V drop.

Something doesn't seem right here. Would you expect such a drop across a relay coil? Is two coils in series a bad idea? What alternatives do I have?

28 February 2011, 2031
OK, answered my own stupid question. Just ran a separate +ve lead from one coil to the next, and then separate grounds. Duh! I really should try and think before I act. :D

I've let the smoke out of my ignition coil in the process though. So one problem solved and another created. :(

01 March 2011, 0330
You are going to be the wiring guru after all of this! :) Keep the faith!!!

01 March 2011, 0858
Nice! I'm having a very similar problem relay coil inline with the contactor circuit that doesn't seem to be working). Based on this, maybe i'll try moving the coil negative to go straight to ground (well, isolated controller RTN) rather than the next link in the contactor circuit. Thanks!!!

01 March 2011, 0934
You are going to be the wiring guru after all of this! :) Keep the faith!!!
It's all a good learning exercise. :) Just as long as I don't kill myself trying, right? :D

Hope this works for you Tango!