Heated seats with engine off

[Nick R]

I was kind of curious about this. I stopped tonight at a restaraunt to pick up dinner on the way home, curbside takeaway. I sat in my car outside for about 10 minutes. I was fairly low on gas, so I shut off the car and ran on aux, and out of curiosity cranked up the heated seat to max, and to my surprise, it still ran- even while on battery.

This brought up an interesting question: How long would that take to drain the battery, and would the car automatically shut it off once the battery got to a critical point?

I had assumed up until this point that the heated seats would not work with the engine off: apparently I was wrong.

 

[spasm3]

What size fuse controls the seat warmer? That might give some insight as to the maximum draw in amps. I would guess 75% of what the fuse is rated.

 

[Rand]

what exactly does shut off car and ran on aux mean?

you had the key on accessory?

FWIW. thats normal as far as I know.

Seat heaters are usually in the 45Watt range.

 

[Kuato]

Originally Posted By: spasm3
What size fuse controls the seat warmer? That might give some insight as to the maximum draw in amps. I would guess 75% of what the fuse is rated.


On the right track. Fuses are rated in amp/hours. First find the correct fuse and rating. Then check battery as to rated amp/hours. Divide battery capacity by fuse rating and you will have your answer. Of course this will be off somewhat, since the amp rating of the fuse is the maximum capacity, above which it will trip, so battery life will be slightly longer than calculated.

 

[NMBurb02]

Seeing as your vehicles are relatively new, they may have a battery saver mode, which my '06 Grand Prix has, which may cut power to the seat heaters when the battery hits a certain charge level. Your manuals might shed some light on that topic.

 

[Chris142]

Im guessing that it would drain the battery pretty quick.

 

[eljefino]

I recall a GM(?) FSM claiming the rear window defogger would cut out if the volts dropped enough, while running.

If you have a body control module giving you your phantom power there is almost certainly a battery saving mode.

And it sounds pretty nice.

 

[SteveSRT8]

Originally Posted By: Nick R
I was kind of curious about this. I stopped tonight at a restaraunt to pick up dinner on the way home, curbside takeaway. I sat in my car outside for about 10 minutes. I was fairly low on gas, so I shut off the car and ran on aux, and out of curiosity cranked up the heated seat to max, and to my surprise, it still ran- even while on battery.

This brought up an interesting question: How long would that take to drain the battery, and would the car automatically shut it off once the battery got to a critical point?

I had assumed up until this point that the heated seats would not work with the engine off: apparently I was wrong.


In our fleet trucks the battery is automatically disconnected after a certain voltage threshold is reached. The intent is to save the battery.

NONE of the accessories work after about ten minutes or so anyway due to a timer on the truck that goes by when you turn it off. Either by time or open a door...

 

[gathermewool]

Kind of a misnomer, battery savings mode. Sounds more like a slow killer than a stab to the heart. For me, if the car is off, all accessories are off as well.

 

[IndyIan]

I was actually wondering the same thing a few days ago, in case I got snowbound sometime.
A quick search says a car battery has around 45 amp hours, and if the seat draws 45-60 watts that would give you 8-10 hours without any other draws. But realistically I'd think you would be prudent to only go for an hour or 2 to not stress the battery too much, especially to restart the car in cold weather.
10-20 minutes here or there probably is insignificant, but I do make sure to turn off the passenger seat if its left on.

 

[SteveSRT8]

Originally Posted By: gathermewool
Kind of a misnomer, battery savings mode. Sounds more like a slow killer than a stab to the heart. For me, if the car is off, all accessories are off as well.


Call it whatever you want, it keeps you from walking!

 

[gathermewool]

Originally Posted By: SteveSRT8
Originally Posted By: gathermewool
Kind of a misnomer, battery savings mode. Sounds more like a slow killer than a stab to the heart. For me, if the car is off, all accessories are off as well.


Call it whatever you want, it keeps you from walking!


You don't agree that, under normal circumstances, a nanny device shouldn't have to turn accessories off to let you know you've been drawing on the battery too long? I'm not talking about accidentally leaving a light on...

 

[SteveSRT8]

Originally Posted By: gathermewool
Originally Posted By: SteveSRT8
Originally Posted By: gathermewool
Kind of a misnomer, battery savings mode. Sounds more like a slow killer than a stab to the heart. For me, if the car is off, all accessories are off as well.


Call it whatever you want, it keeps you from walking!


You don't agree that, under normal circumstances, a nanny device shouldn't have to turn accessories off to let you know you've been drawing on the battery too long? I'm not talking about accidentally leaving a light on...


I hate anything that adds to unneeded complexity. Just creates another failure point.

But since I have many other drivers, some who are not paying attention like you or I would, and this solid state device rarely fails, it works well here...

 

[gathermewool]

Originally Posted By: SteveSRT8
Originally Posted By: gathermewool
Originally Posted By: SteveSRT8
Originally Posted By: gathermewool
Kind of a misnomer, battery savings mode. Sounds more like a slow killer than a stab to the heart. For me, if the car is off, all accessories are off as well.


Call it whatever you want, it keeps you from walking!


You don't agree that, under normal circumstances, a nanny device shouldn't have to turn accessories off to let you know you've been drawing on the battery too long? I'm not talking about accidentally leaving a light on...


I hate anything that adds to unneeded complexity. Just creates another failure point.

But since I have many other drivers, some who are not paying attention like you or I would, and this solid state device rarely fails, it works well here...


Very good point.

 

[Doog]

Originally Posted By: gathermewool
Originally Posted By: SteveSRT8
Originally Posted By: gathermewool
Kind of a misnomer, battery savings mode. Sounds more like a slow killer than a stab to the heart. For me, if the car is off, all accessories are off as well.


Call it whatever you want, it keeps you from walking!


You don't agree that, under normal circumstances, a nanny device shouldn't have to turn accessories off to let you know you've been drawing on the battery too long? I'm not talking about accidentally leaving a light on...


It is a power saving mode built into the firmware logic on the control modules. Made to keep the vehicle in running mode as long as possible and prevent the advent of a battery failure. Not a "nanny device".

 

[hattaresguy]

Modern cars will kill the power before the battery gets to low to start the motor. With the seat heaters that will happen pretty quickly!