Best way to hook up seat heaters

[Ashyukun]

When I had the new seat covers put on my seats a few months back, I had seat heaters installed at the same time. However, I had other fish to fry at the time and didn't wire any of it up to the car at the time. As weather is starting to turn cold and I have the car in the garage dealing with another issue I figured it would be a good time to hook it up. However, I'm not certain the best way to do so.

What I was thinking about doing was hooking it up directly to the battery (fused, of course...) via a relay triggered by the aux relay- that way it would not be interfering with any of the other circuits in the car, but would only work when the engine was on (so I couldn't accidentally leave it on and either start a fire (shouldn't be possible, but...) or drain the battery down.

Thoughts?

[DMCMW Dave]

I just installed a set in a car and considered doing the same thing. Unfortunately the seat heaters that this particular owner provided were intended to be connected straight to the battery, and I wasn't about to run the heaters directly off the car's aux circuit due to the added load. The heaters themselves came with a relay arrangement, but all that did was put them in series for low heat and in parallel for high heat. I was disappointed that they didn't have some sort of timer to shut off after a while (like on other cars I've owned).

I considered working out a relay arrangement as you describe but in this case we decided that the owner would be careful and use the battery disconnect anyway so we didn't go that far.

All you would really have to do is have a relay (or two) triggered by the main relay and fed from the battery and you whould be fine.

[TTait]

Fair warning though, I have a unmarked switch installed next to the driver window switch, one of the ones sold by Houston...

The thing is - I turn that switch on with my elbow all the time. At least once each time I drive the car. If you use one of these switches, I'd also look at putting a small idiot LED somewhere so you know when you have hit it by mistake.

Maybe its just me, but it can't be - statistically speaking.

[WelmoedJ]

If there's no breaker (switch) somewhere in the feed to the seat heaters, the heaters will draw current the moment the aux relay is turned on.
Having them on for too long may drain the battery to the point your car will have problems starting.

Therefore, like Tom advices and IMHO a switch in this circuit is a must.
Instead of a toggle switch in one of the dummy switches you may prefer a push button type switch with hold function.
You also could rework the dummy to operate as the failsafe cap of a command switch (meaning you have to open/flip the cover before using the switch).
That way your new switch also is hidden.

Welmoed.

[Bitsyncmaster]

You could wire your relay to the rear defrost indicator light. If you don't use the rear defrost, just pull that defrost "timer". That should turn the heaters off with the key and also remind you they are on.

I'm still thinking of doing that with my wideband select function. I also hit that added switch I used beside the window switch.

[Dracula]

I was thinking about installing seat warmers when I have my seats redone, but it seemed to be a tad redundant, since I can't drive the car the only time its cold enough to need them. I may still go with ventilated seats, though.

I also used to have problems engaging the dummy switches when I a manual engagement switch for the cooling fans in that position. It was another reason I designed a replacement.

In relation to this thread itself, shouldn't this be in the "Mods" section of the forum?

[DMCMW Dave]

The seat heaters that I used came with a three postion (HI - OFF - LO) switch that was about 1/2" diameter, and included red/green LEDs for indicators. I drilled holes in the two dummy switches to mount them. They were intended to be mounted in the die panels of the seats (in most cars). Could easily have been mounted next to the lighter but I don't like drilling holes in OEM metal non-replaceable parts.

[Farrar]

I had a heated seat by accident once when I accidentally severed the power leads from the seat belt sensor and they ended up touching the seat rail. You have been warned...

Farrar

[Ashyukun]

The seat heaters that I used came with a three postion (HI - OFF - LO) switch that was about 1/2" diameter, and included red/green LEDs for indicators. I drilled holes in the two dummy switches to mount them. They were intended to be mounted in the die panels of the seats (in most cars). Could easily have been mounted next to the lighter but I don't like drilling holes in OEM metal non-replaceable parts.

That sounds like almost exactly what I have and how I plan to mount the switches. I do kind of like the idea of wiring them up to use the defroster light (also reminds me I should figure out why my defroster isn't working right...), but I think the lights on the switches themselves should be good enough...