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Re: Slightly different Seat Heater Question

MSV96 wrote:
> In a message dated 12/22/97 glen powell <gpowell@acacianet.com> writes:

> I think it is Nichrome wire (I believe I read that here in an old
> post...perhaps one of Igor's?).

Yes, that was mine, over a year ago. I think it's NiCr, at least
partially, woven into Cu strands.
> Since I too will undertake this project soon, is the consensous to twist and
> heatshrink or solder and heatshrink? 

Solder it. You need to achieve as little connection resistance as
The resistance of each cushion is only 0.7 to 1 ohms. At 14v from the
Alt you'll get about 200w max (I am neglecting losses for simplicity).

If your connection has, say, 0.3 ohm of parasitic resistance, you'll get
about 70w of losses applied to a tiny contact area of the said
connection and it will burn out (in notime).

>My thoughts are that soldering invites failure.

True, but unless you have the facilities for spot welding tiny
electronic components, soldering is still the best approach. 
I once broke the connector on the Intercooler temperature sensor, and
found out that the connector was made out of steel, I couldn't solder
the wire to it.
So I cut off the second wire, took the sensor to work and spot welded
two little (1x5mm) strips of chemically pure Ni shim stock, that I had
in my lab.
After that resoldering of the wires became a snap.

Interweave the ends of the heater wire, solder them and heat shrink.
Don't twist them together.

I fixed my both seats 3 years ago, they still work well.
Igor Kessel
'89 200TQ -- 18psi (TAP)
'98 A4TQ -- FINALLY!
Philadelphia, PA