6v relay

Here is my question. If I connect a 6V relay to 12V, will it fail? I searched and searched and could not find an answer to this question! Thanks,

Yes it will fail.  If you have 2 of them, you can wire the coils in series to make it a 12 volt relay.

I will occasionally run a 5vdc relay with a 100 ohm resistor in series with the coil on a 12vdc system and I've never had one fail.Kevin Pierson

The point is it's only the coil voltage that's important, NC (87a), NO 87 and common (30) are normally listed in the specs along with amperage. E.g. 6amps at 250 volts.

Find out the solenoid's/coil's resistance. The get the closest resistor and connect it in series with the solenoid. . EG - if 60 Ohm, get a 1 Watt 56 or 68 Ohm resistor. If 160 Ohm - get say a 1/2 Watt 150 (else 180) Ohm resistor. As above, contacts for 6V & 12V don't matter - it's their curent rating that count. FYI - resistor wattage rating is VxV/R where V = voltage across resistor (say 6V; assume up to 7-8V in 12V vehicles) and R = resistance. EG - 6x6/60 = 36/60 = 0.6W rounded up to 1W. 6x6/160 = 0.225W, but use 1/2W minimum resistor (physically robust etc). Or worst cases: 8Vx8V/60R & 160R = 1.06W & 0.4W; so 1W & 0.5W should be fine.