[Sean Graham]

So, it turns out that the heated steering wheel uses more than a single seat.

Inspired by the Volt post in their forum, I decided to take my ammeter to by Bolt and measure what was happening with both the heated seats and steering wheel.

Long story short:

One Seat:
- High 35W
- Medium 28W
- Low 20W

Steering Wheel: 47W

The values for the seats are odd. Regardless of the setting, when you turn them on they start at 3.85A and drop pretty quickly to 3.5A until the seat is at the desired temperature.

On high, this then alternates between 3.5A and 1.8A with 50/50 cycle (every 10 seconds).

On medium, this alternates between 10 seconds at 3.5A and 6 seconds off.

On low this is 8 seconds on full, 10 seconds off.

With both seats running at full, it was roughly 5A (65W) average, bounced around a lot.

The steering wheel starts at 6A, decreases over time to 3.6A continuous.

12V rail voltage was almost exactly 13V at this time

#Science

 

[JC Bolt]

I would not have predicted that, based only on surface area. Thanks for the good info!

 

[LectricBill]

Thanks for the info. I'm used to being concerned about heating elements' draw, having had to deal with anemic motorcycle alternators and heated clothing.

As far as the Bolt is concerned, if I'm looking at pulling 82W out of a battery that routinely supplies 20,000 watts, I'm gonna go for comfort!

 

[Catster]

The steering wheel heater seems to start out quite hot, and then the temp tapers back to a comfortable warm after a couple of minutes, making me inclined to leave it on even after the wheel and interior has warmed up. I would think that this warm wheel mode would be drawing significantly less than a heated seat. Knowing this still won’t prevent me from using mine! Blower on 2 speed (after initial warmup on 3 or 4), temp on 72 or less, heated seat on 1 makes for a cozy driver’s seat!

 

[GJETSON]

So, it turns out that the heated steering wheel uses more than a single seat.

Inspired by the Volt post in their forum, I decided to take my ammeter to by Bolt and measure what was happening with both the heated seats and steering wheel.

That is pretty amazing. My back feels pretty warm with the seat on high. The wheel has never felt that warm. But that could be a difference in the sensitivity of the nerves.

I did a 131.7 mile drive yesterday, in low to mid forties weather, and total overcast. I ran the seat and steering wheel heater the whole time, and turned the heat on at 74 F whenever the cabin felt cool. I had Torque Pro going the whole time. After the first 10 miles the trans temp had risen to 120 F, and stayed between 90-120 F the whole way, depending on speed. I assume that thermistor is in the motor/gear case somewhere? At least it reflects the power electronics/motor coolant loop temperature.

Watching the cabin heat pop up to 7500 watts when I'd turn it on got me to wondering why GM didn't bother to run the power electronics loop through the cabin heater loop, on its way to that big radiator at the front? Tesla does that on the Model 3. Actually, Tesla doesn't use a tankless heater at all, just messes with the phase timing on the motor to get it to overheat a bit, and runs that through the dash heater core, on the way to the radiator..

How much could a valve and some hose cost to preheat the cabin heater coolant to 90-120 F?

 

[NY-Rob]

Interesting findings @Telek ....


Thanks for your efforts!


Have definitely noticed the steering wheel heat modulating down after the first few min... it's quite hot at first then just settles on warm for the duration.

 

[hatchy]

I use the steering wheel heater quite often. And I'm in socal. Pretty much the only time I use cabin air heat is for passengers. Majority of time the a/c is in use it is for passengers too. I never had seat or wheel heat before, and I didn't think I would like it. Man I was wrong. Its great even in mild cold like what we have here.

messes with the phase timing on the motor to get it to overheat a bit, and runs that through the dash heater core, on the way to the radiator.

Elegant solution.. me likely.