How do you wire 2 12v relays in series to make them 24 volts?

ilyafish · May 07, 2009, 11:05:41 PM

Long story. But we leave tomorrow and ended up acquiring some new equipment today which is forcing us to now take the trailer since there is no room in the bays. Wasnt anticipating this at all, so obviously no time to order 24 volt relays off the internet and get them shipped. I will make calls tomorrow to a few places and try to locate 24 volt relays, but assuming i will have a hard time finding them, just seeing how i would go about wiring 2 12v relays in series to make it 24. A diagram would be awesome. I plan on using Craig's schematic on his toad converter.

Nusa · May 07, 2009, 11:56:21 PM

Umm....just wire the coils of two 12V relays in series on the 24V activating circuit, observing polarity if there's a diode involved. Wire up the rest of one relay same as if it were a 24V one. Ignore the other relay...you're only using it to play the role of a cheap resistor.

fe2_o3 · May 08, 2009, 12:03:01 AM

Many forklift repair companies will have 24 volt relays. Cable

Sean · May 08, 2009, 12:05:45 AM

http://www.busconversions.com/bbs/index.php?topic=11296.0

JohnEd · May 08, 2009, 12:55:07 AM

IM,

First of all, to do this the 12 volt relays must have a ground "terminal". Many us the frame of the relay as the path to ground and making that work is far to complicated for this situation. Connect the relays like you would connect two 12 volt bats.....+ to - and then the free minus gets connected to ground and the free positive terminal on the second relay will be the point where you attach the controling signal. The little cube relays that are rated for 30 amps would work really well and they are so cheap you would not consider the ebay option unless you live way out there.

HTH,

John

jjrbus · May 08, 2009, 03:13:59 AM

Hmmmmmmm?? Its real early and I just woke up so maybe I am missing something. If you are doing what my slowly awakening brain thinks you are doing, just replace the bulbs in the trailer with 24V bulbs or get a set of magnetic lites and replace the bulbs in them with 24 volt bulbs. Then do the fancy hi tech stuff at your liesure.
HTH Jim

Chopper Scott · May 08, 2009, 05:24:09 AM

Could you wire a light and then the relay in series. Just a thought. Later

JackConrad · May 08, 2009, 05:33:56 AM

Quote from: Chopper Scott on May 08, 2009, 05:24:09 AM
Could you wire a light and then the relay in series. Just a thought. Later

Hmmm, i think that would work and would also give you a built in test light to confirm relay is working. Of course, if the light fails, the relay will quit working, UGH Jack

Len Silva · May 08, 2009, 06:42:18 AM

The typical 12 volt automotive relay coil is about 90 ohms, 1.5 watts. Use a 100 ohm, 5 watt resistor (Radio Shack 271-135) $1.99 for two.