$28 seat heat pad replacement DIY

[Turbo_Bimmer]

Originally Posted by pezho405

Mine burned through the seat and made a hole. if i turn it on and look in the hole i see sparks and stuff

I suggest that you don't use it until you fix it. Some members had damaged clothings, and others almost lost control of their vehicle when surprised by the burning on their butt!

[pezho405]

Originally Posted by Turbo_Bimmer

I suggest that you don't use it until you fix it. Some members had damaged clothings, and others almost lost control of their vehicle when surprised by the burning on their butt!

Yeah i was waiting for my friedn to drive up sitting in car with heater on, the drive there i kept smelling something burn slightly thought it was possibly oil or something but then kept sitting there and felt my side of my but get hotter and hotter..

There should be a recall for it or something, saftey issue isnt it?

[stewey]

Thanks Turbo! Seems like putting the new pad between the old pad and the leather is key to keeping it in place. Or would you do it differently next time?

I was considering using an even higher value resistor. I think a .68 ohm resistor will give us 68W. I think it would take 1.44 ohms to get us back to 50W. Am I calculating this wrong?

Digikey has 1.2 ohm resistors rated for 60W which should get us to 54W. Also, the 60W resistors are about twice as much as the 50W ones. I take it you are worried about running more current through them than they are spec'd for?

[bcredliner]

Great write up!

[Turbo_Bimmer]

Originally Posted by stewey

Thanks Turbo! Seems like putting the new pad between the old pad and the leather is key to keeping it in place. Or would you do it differently next time?

I was considering using an even higher value resistor. I think a .68 ohm resistor will give us 68W. I think it would take 1.44 ohms to get us back to 50W. Am I calculating this wrong?

Digikey has 1.2 ohm resistors rated for 60W which should get us to 54W. Also, the 60W resistors are about twice as much as the 50W ones. I take it you are worried about running more current through them than they are spec'd for?

You can put the pad directly under the leather or under the existing BMW pad. The heating is faster directly under the leather. I found that the X5 was slow to heat compared to my ex-E46, that's why I installed it directly under the leather.
I think a higher value resistor could be used for a more 'OE' heating speed / power but the wattage of the resistor will need to be increased since more voltage will drop through it.

[stewey]

Thanks again Turbo. I think I'll start with a 50W 1.2 ohm resistor. Looks like that will be ~54 watts across the circuit with ~30 going into the mat and ~24 going to the resistor.

[traveldad]

I'm impressed with your solution and ability. It will work on most autos.

I would have been inclined to try and find a seat cover from a wrecked vehicle, wonder what becomes of good seats. traveldad

[alinvictor]

Thanks Turbo. You made a lot of us happy.....

I already ordered my parts and something I would mention is that a 2ohm 100w resistor may do the job for the ones that will like some slower heating. To keep in mind is that the power should be calculated at ~13.0-13.5V considering the car is running and the alternator/regulator is pushing voltage.

[puddinboo]

nice pics , only thing i would add is to get a pair of hogring plyars , to make things go alot easier for those metal hog rings that hold the fabric to the seat frame.

[m5james]

Nice job