garsh
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Heated Seats & Steering Wheel - what's the power draw?

Mon Nov 12, 2012 7:04 am

Has anybody measured the power draw of the heated seats or the steering wheel?

I think I'm noticing a decrease in efficiency when I use them, so I'm wondering if they aren't quite as insubstantial as I thought they were.
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EatsShootsandLeafs
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Re: Heated Seats & Steering Wheel - what's the power draw?

Tue Nov 13, 2012 10:53 am

Not sure. I'm not even sure they impact the "accessories" reading, or whether its reading of them is accurate. I cannot imagine the draw is that substantial, though.

Segue: anybody else's steering wheel pulse? By this I mean it gets really nice and warm at first and then after a couple minutes will cool down until it's barely warm, then heat up again. Really annoying. This is my first car with a heated steering wheel though and it's a really nice comfort.

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dgpcolorado
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Re: Heated Seats & Steering Wheel - what's the power draw?

Tue Nov 13, 2012 11:54 am

EatsShootsandLeafs wrote:Not sure. I'm not even sure they impact the "accessories" reading, or whether its reading of them is accurate. I cannot imagine the draw is that substantial, though.
According to Phil ("Ingineer") the accessories meter is fake: it just adds up fixed values for the baseload and accessories that are on, for example, the headlights. So far as I am aware it doesn't have a value for the heated seats or steering wheel heater, perhaps because they weren't on the first LEAFs and the algorithm wasn't adjusted for cars with the cold weather package.
Segue: anybody else's steering wheel pulse? By this I mean it gets really nice and warm at first and then after a couple minutes will cool down until it's barely warm, then heat up again. Really annoying. This is my first car with a heated steering wheel though and it's a really nice comfort.
The steering wheel heater has a thermostat that cycles it on and off to keep it from overheating.
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Nubo
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Re: Heated Seats & Steering Wheel - what's the power draw?

Tue Nov 13, 2012 12:41 pm

EatsShootsandLeafs wrote:Not sure. I'm not even sure they impact the "accessories" reading, or whether its reading of them is accurate. I cannot imagine the draw is that substantial, though.

Segue: anybody else's steering wheel pulse? By this I mean it gets really nice and warm at first and then after a couple minutes will cool down until it's barely warm, then heat up again. Really annoying. This is my first car with a heated steering wheel though and it's a really nice comfort.


AFAIK, the 12V accessory draw is "estimated". Not sure how intelligently but it doesn't necessarily seem to track what I'm actually doing with the car. You can get some idea of the max current draw for the steering wheel and seat heating by looking at the fuses; will give you an upper bound and the actual use will be less. Definitely a lot less than the main heater!

The steering wheel heat is welcome, but frustrating. I understand the idea of a thermostat but the way it's implemented seems silly. Imagine if your home thermostat worked this way! :o :roll:
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Re: Heated Seats & Steering Wheel - what's the power draw?

Tue Nov 13, 2012 12:49 pm

one thing that can be said is, they are a fraction of what the heater draws and worth every penny!
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dgpcolorado
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Re: Heated Seats & Steering Wheel - what's the power draw?

Tue Nov 13, 2012 7:03 pm

Nubo wrote:...The steering wheel heat is welcome, but frustrating. I understand the idea of a thermostat but the way it's implemented seems silly. Imagine if your home thermostat worked this way! :o :roll:
My home thermostat does work this way: if the furnace ran continuously my house would rapidly overheat. I even have my thermostat programmed to have a wide temperature variation so that the furnace doesn't cycle on and off very often but runs longer each time it kicks on.

Consider that the steering wheel heater needs to heat up enough to be useful when the car is below 0ºF but not overheat if someone uses it at 55ºF. Given that large range, just having a resistance heater that runs continuously would be impractical. Having a resistance heater for such a tiny application that can vary temperature by adjusting current flow, or use multiple heating elements depending on temperature, would add complexity and cost. By comparison, a thermostat that turns the current on or off is pretty simple.

At least one person has already complained that it is "too hot"; barring an actual defect, I presume that if the steering wheel heater is "too hot" it is being used in conditions too mild for it to be needed.
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Nubo
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Re: Heated Seats & Steering Wheel - what's the power draw?

Tue Nov 13, 2012 7:48 pm

dgpcolorado wrote:
Nubo wrote:...The steering wheel heat is welcome, but frustrating. I understand the idea of a thermostat but the way it's implemented seems silly. Imagine if your home thermostat worked this way! :o :roll:
My home thermostat does work this way: if the furnace ran continuously my house would rapidly overheat. I even have my thermostat programmed to have a wide temperature variation so that the furnace doesn't cycle on and off very often but runs longer each time it kicks on.

Consider that the steering wheel heater needs to heat up enough to be useful when the car is below 0ºF but not overheat if someone uses it at 55ºF. Given that large range, just having a resistance heater that runs continuously would be impractical. Having a resistance heater for such a tiny application that can vary temperature by adjusting current flow, or use multiple heating elements depending on temperature, would add complexity and cost. By comparison, a thermostat that turns the current on or off is pretty simple.

At least one person has already complained that it is "too hot"; barring an actual defect, I presume that if the steering wheel heater is "too hot" it is being used in conditions too mild for it to be needed.


I understand the need for a thermostat. I'm just saying the wide temperature swings are neither necessary nor useful.

Most home thermostats have a maximum swing of 3 degrees or so. Going much larger is counter-productive because people start feeling drafts and turn up the heat to compensate. Going by feel I'd say this steering wheel heater has a swing of 30-35 degrees.

There is nothing complex or expensive about putting a feedback device in the loop. I imagine there already is a simple one, as you suggest -- to turn on and off at certain temperatures. It doesn't need to "adjust current flow", it just needs to turn on and off more frequently so that the swings are centered more closely around the mean. Why go from "too hot" to "too cold"? I want a comfortable steering wheel, not a "Goldilocks Device". :lol:

Driving for 10 minutes with a "cold" heated steering wheel seems ludicrous.
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garsh
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Re: Heated Seats & Steering Wheel - what's the power draw?

Wed Nov 14, 2012 7:27 am

dgpcolorado wrote:So far as I am aware it doesn't have a value for the heated seats or steering wheel heater, perhaps because they weren't on the first LEAFs and the algorithm wasn't adjusted for cars with the cold weather package.
That's correct. I'd be happy with that sort of estimate of usage. It's unfortunate that Nissan didn't include these values in the meter.
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Randy
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Re: Heated Seats & Steering Wheel - what's the power draw?

Wed Nov 14, 2012 7:42 am

The aftermarket seat heaters I bought are rated something like 50-60 watts each...Noise in the scheme of 20,000-50,000 watt average traction battery usage...

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Re: Heated Seats & Steering Wheel - what's the power draw?

Wed Nov 14, 2012 8:00 am

LOVE the heated steering wheel!

As far as the pulsing, it reminds me of staying with my grandmother when I was a kid and having electric blankets on the bed. They would heat up, turn off and then heat up again. They weren't fancy enough to maintain a set temp, just a setting of how long they stayed on before cycling.

I find myself holding the top of the steering wheel as it warms up and working my way down as it gets hot and then working my way back up. Maybe it helps you stay awake?

Philip
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