Monday, June 16, 2008

2nd relay added

Some time ago I added a switch that allowed me turn off the electrical portion of the heater system. By default the Plantdrive kit (at least when I purchased mine) wires the Vegtherm and 6 port Pollak fuel selector valves together on the same switch. To do this a relay is used. I didn't really know what the relay did, I just installed as directed.

Because the Vegtherm and resistance wire I added draw a large amount of amperage one must use large gauge wire for these items. Since a switch is used you must get a very high amperage one. The problem with this is that you end up running 10 gauge wire through out the dash which isn't practical. A relay lets you use smaller gauge wire for the switch portion of the system but yet deliver the high amperage load to the destination (Vegtherm / resistance wire in this case).

As mentioned, the electric heaters and Pollak are on the same switch and hence relay. When I added the separate switch to turn off the electric portion of the system I had to connect it to the high amperage output of the relay. This required using heavy duty (10G) wire to the dash and switch. After I burned out the second switch with a rating of 3o amps I installed a switch with a 50amp rating. This switch worked fine but would still get hot at the connectors and I never fully installed it into the dash because it wouldn't fit as it was too large for the knockout (forgot to take a picture).

After the 2nd switch burned up I posted a question on the forums about finding a 50amp switch and someone suggested I add an additional relay. Today I did that and it seems to be working. I have to post again to see if I wired it correctly since I just mirrored the existing relay. I have to put the wiring harnesses back on

wiring is as follows:

Left relay (original)
red on top is power in from breaker (the thing between them)
green is switch output to fuel selection valve(Pollak / 3 port valves) w/additional 12v supply
black wire ground
bottom red provides high amperage output to second relay on right

Right relay (new)
red on top power in from left relay
black ground
red on bottom is high amperage output to Vegtherm/injection line heaters
Blue is to electric on/off switch in dash w/additional 12v supply

Update: I had to pull power for the 12v switched power supply for the 2nd relay(blue wire) from the diesel/VO switch so that the 2nd relay is only powered when the switch is thrown to VO. Otherwise the relay would be on all the time and I would have to remember to switch it on or off.
There are other ways to do this (see smellslikefries's consol). My system is extremely manual and computer controlled systems are available along with variations on what I've down.

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