[dopper99]

I noticed today the heated rear window seemed to take a heck of a long time to clear this morning and a lot longer than my old E90. There was no ice on the window – just condensation. I also noticed that the mirrors take a while to clear, although I’m sure I’ve read this on another thread. Is this normal for an F30?

Conversely, the windscreen actually defrosts very well – with the windscreen blower on. Even with ice on it, it will defrost completely with a light frost in around 5 mins without the need to use a scraper or de-icer. First car I’ve had that does that (bar Ford’s quick clear windscreen).

[Thompjas]

Spooky, I have just posted a post around teh same issues - though I believe that the windscreen on mine clears slowly when compared to my previous Insignia.

Deffo the rear window takes absolute ages, even more important on the saloon where we do not have a wipe to clear off the glass.

Just out of interest, what blower settings are you using to clear the windscreen?

[dopper99]

Hey Thompjas, yes seen your thread too!!

To defrost the windscreen I just press the windscreen button, on the far left and touch nothing else. I think the A/C is on, but not sure if that works below a certain temp anyway. It was -0.5 deg C this morning and it defrosted very well.

It defrosted similar a couple of times last week too (I only had my car last Monday so still getting used to everything).

[gtsussex]

Does take a while. Tend to start car, set defrost & turn on heated seat and wheel, lock car, have cuppa and then get into clear heated car with hot seat and steering wheel. Know you're not allowed to do on road but nothing wrong with doing on private land.

[Eccles Ken]

I have always put my car in garage so happens minimum no of times . Incidentally I have space only for BMW below 15ft 3ins - do hope when I get it measurements of length specified are right otherwise ".........boohoo".......

[d4springer]

I noticed the rear window taking a while to defrost also, seems a bit longer than on the E92, didn't notice so much on the mirrors though, had a lot of steam rising of them, looked a bit odd from the outside! But rear window was definitely a while before I even started to see the elements appearing. I try not to use de-icer so I tend to start the car up 5 to 10 mins before I head off.

[HighlandPete]

Speed of defrosting will depend to a great degree on consumer load from start up. Energy management will clock or limit the high energy users, if there is not the battery or alternator capacity to serve them all.

The demands can be massive if you have rear heated screen, mirrors, heated seats and the like all switched on together. There is also the electric PTC heater element in the HVAC unit, which gives the more instant front screen demisting. Even worse if the engine is on idle, as alternator is not at full capacity.

BMW set a 'priority' list for consumers, so some functions get reduced output. Typically heated rear screen and mirrors are high up on that list for electrical load reduction.

HighlandPete

[dopper99]

Seems they are all the same then with regards the time it takes to clear the rear screen. One could assume it may be some “ECO” thing so that less energy is used to save fuel – probably.

[dopper99]

Originally Posted by HighlandPete

Speed of defrosting will depend to a great degree on consumer load from start up. Energy management will clock or limit the high energy users, if there is not the battery or alternator capacity to serve them all.

The demands can be massive if you have rear heated screen, mirrors, heated seats and the like all switched on together. There is also the electric PTC heater element in the HVAC unit, which gives the more instant front screen demisting. Even worse if the engine is on idle, as alternator is not at full capacity.

BMW set a 'priority' list for consumers, so some functions get reduced output. Typically heated rear screen and mirrors are high up on that list for electrical load reduction.

HighlandPete

That sounds a more plausible explanation.

[Thompjas]

I will switch off Eco Mode another time and see if 'comfort' assists more !!

[dopper99]

Originally Posted by Thompjas

I will switch off Eco Mode another time and see if 'comfort' assists more !!

I think the car starts in Comfort mode?
Unless you are making a conscious effort to put it in ECO Pro mode then it should already be in Comfort on start up.

[d4springer]

Originally Posted by HighlandPete

Speed of defrosting will depend to a great degree on consumer load from start up. Energy management will clock or limit the high energy users, if there is not the battery or alternator capacity to serve them all.

The demands can be massive if you have rear heated screen, mirrors, heated seats and the like all switched on together. There is also the electric PTC heater element in the HVAC unit, which gives the more instant front screen demisting. Even worse if the engine is on idle, as alternator is not at full capacity.

BMW set a 'priority' list for consumers, so some functions get reduced output. Typically heated rear screen and mirrors are high up on that list for electrical load reduction.

HighlandPete

I don't switch on any other heating elements first thing, I even turn the stereo off and make sure the car is in Comfort and mostly don't bother with the max windscreen blower, still seems to take longer for the rear window to heat up, not a big deal but I did notice it in this car compared to my last one

[Thompjas]

Originally Posted by dopper99

I think the car starts in Comfort mode?
Unless you are making a conscious effort to put it in ECO Pro mode then it should already be in Comfort on start up.

I do have a 320Ed, so it always starts in Eco Mode - I will have to read the manual to see if I can alter this for the winter months !

[dopper99]

Originally Posted by Thompjas

I do have a 320Ed, so it always starts in Eco Mode - I will have to read the manual to see if I can alter this for the winter months !

Oh, didnt realise some cars start in ECO mode.
I tried it once.

[HighlandPete]

Originally Posted by d4springer

I don't switch on any other heating elements first thing, I even turn the stereo off and make sure the car is in Comfort and mostly don't bother with the max windscreen blower, still seems to take longer for the rear window to heat up, not a big deal but I did notice it in this car compared to my last one

Is this while stationary, or are you on the move?

Putting the electrical loads in perspective, even if we switch off some of the smaller consumers, we still run the heavy demand items like the HVAC heating element and rear screen.

I haven't the data for the F30 but in the E9* diesel models the PTC auxiliary electric heater is 1250 watts. Even that is limited in current draw.

The only power that is available to the electric auxiliary heater is the excess power from the alternator. The maximum heat output available is 1250 watts. At maximum heat output, the current draw is limited to 74 amperes (± 10%). The electronic circuitry in the electric auxiliary heater automatically adjusts to the respective minimum. (Request of the IHKA and limitation by the DME.)

That is a massive part of the available energy at idle and will be 'doing its best' to warm the cabin as fast as possible. Now add a rear screen and mirror elements, all energy hungry.

If you are on the move, then the alternator will be generating more amperage, and we get faster demist response.

HighlandPete

[TonyS]

Originally Posted by HighlandPete

Is this while stationary, or are you on the move?

Putting the electrical loads in perspective, even if we switch off some of the smaller consumers, we still run the heavy demand items like the HVAC heating element and rear screen.

I haven't the data for the F30 but in the E9* diesel models the PTC auxiliary electric heater is 1250 watts. Even that is limited in current draw.



That is a massive part of the available energy at idle and will be 'doing its best' to warm the cabin as fast as possible. Now add a rear screen and mirror elements, all energy hungry.

If you are on the move, then the alternator will be generating more amperage, and we get faster demist response.

HighlandPete

Yikes - 1250W? You're right, that is a huge load.

Is this HVAC heater standard on all F30s, or only fitted on diesels as they heat up slower? I wasn't even aware that it existed before now.

[HighlandPete]

Originally Posted by TonyS

Yikes - 1250W? You're right, that is a huge load.

Is this HVAC heater standard on all F30s, or only fitted on diesels as they heat up slower? I wasn't even aware that it existed before now.

The Auxiliary PTC electric heating element is listed for F30 diesel models.

Miss it in my petrol 535i, it is the only negative about the car. Miss the fact the 330d diesel, would start giving cabin heat almost immediately.

When I get to the next village (3-miles) ECT is about 53 - 55C (similar to the diesel at around freezing temperatures) I'm no where near at the same cabin heating. It is just warm, where the 330d would be pumping out loads of heat.

It takes a lot of energy to get a warm cabin a freezing temperatures.

Posted this comment in another topic last winter.

I'll add another comment about the amount of heat we need to warm a car.

I've used an electric fan heater (for many years) to thaw out my cars on frosty days.

I run a 2kW heater and it takes about 30 minutes to thaw all windows and put a reasonable amount of warmth in the cabin. That's at around -2C ... in a 3-series touring. It uses a Kilowatt's worth of energy to do the job! Get it any colder and that increases dramatically. 5-series touring takes another 15 minutes to do a similar job as in the 3-series.

Food for thought isn't it? We have alternators of around 200 amp capacity using up to around 8hp, and still we have to have electric consumers being controlled.

I remember the days of living with the 15 amp dynamo, how we have moved on.

HighlandPete

[TonyS]

Originally Posted by HighlandPete

The Auxiliary PTC electric heating element is listed for F30 diesel models.

Miss it in my petrol 535i, it is the only negative about the car. Miss the fact the 330d diesel, would start giving cabin heat almost immediately.

When I get to the next village (3-miles) ECT is about 53 - 55C (similar to the diesel at around freezing temperatures) I'm no where near at the same cabin heating. It is just warm, where the 330d would be pumping out loads of heat.

It takes a lot of energy to get a warm cabin a freezing temperatures.

Posted this comment in another topic last winter.




Food for thought isn't it? We have alternators of around 200 amp capacity using up to around 8hp, and still we have to have electric consumers being controlled.

I remember the days of living with the 15 amp dynamo, how we have moved on.

HighlandPete

Thanks for all that - interesting stuff.

Yes, the electrical power that's required by modern cars is quite amazing. I too was thinking about the old days of dynamos earlier on when I read your previous post

[Betoni]

I wondered if starting the remote auxillary ventilation would help defrost in the morning. So I am sitting in my car (waiting for my daughter to finish gym) with car off and locked and have started the aux ventilation via my IPhone. Interestingly the start/stop button lit up and a slight whiring sound from the dash and I can just (and I mean just) feel a slight breeze if I put my lips to the vent (got a few strange looks doing that one!!!). So don't think that helps or in fact think it does much at all - unless I did something wrong!

I know some people start their cars and then leave it defrosting but how do you lock your car as I thought the keys needed to be in ther car for it run?

Also I was told it not a good idea to leave a cold car idling - although it was my Grandads advice 22 years ago when I had my first car a 1.0 Metro City X so maybe technology has moved on a bit (that car even had a choke!)

[HighlandPete]

Originally Posted by TonyS

Yes, the electrical power that's required by modern cars is quite amazing. I too was thinking about the old days of dynamos earlier on when I read your previous post

When I had my Ford Cortina Mk2 GT, it was fitted with a 22/25 amp dynamo if I remember correctly. We'd have the option to run a pair of decent spot lights, or the wipers, along with main beam on a wet night. Run both and the ammeter indicated you were into negative output.

We had to do our own energy management in those days, or you'd soon get a flat battery.

HighlandPete

[HighlandPete]

Originally Posted by Betoni

I wondered if starting the remote auxillary ventilation would help defrost in the morning. So I am sitting in my car (waiting for my daughter to finish gym) with car off and locked and have started the aux ventilation via my IPhone. Interestingly the start/stop button lit up and a slight whiring sound from the dash and I can just (and I mean just) feel a slight breeze if I put my lips to the vent (got a few strange looks doing that one!!!). So don't think that helps or in fact think it does much at all - unless I did something wrong!

I know some people start their cars and then leave it defrosting but how do you lock your car as I thought the keys needed to be in ther car for it run?

Also I was told it not a good idea to leave a cold car idling - although it was my Grandads advice 22 years ago when I had my first car a 1.0 Metro City X so maybe technology has moved on a bit (that car even had a choke!)

You don't have independent auxiliary heating in the F30/1, just the ventilation option (cold air).

An idling cold engine is not a good idea, never has been. Diesels take ages to warm at idle. Users are doing it for the electrical functions to heat, not really the engine. Best to drive off after a few seconds for fastest engine warm up.

HighlandPete

[Rodders123]

Originally Posted by Betoni

I wondered if starting the remote auxillary ventilation would help defrost in the morning. So I am sitting in my car (waiting for my daughter to finish gym) with car off and locked and have started the aux ventilation via my IPhone. Interestingly the start/stop button lit up and a slight whiring sound from the dash and I can just (and I mean just) feel a slight breeze if I put my lips to the vent (got a few strange looks doing that one!!!). So don't think that helps or in fact think it does much at all - unless I did something wrong!

I know some people start their cars and then leave it defrosting but how do you lock your car as I thought the keys needed to be in ther car for it run?

Also I was told it not a good idea to leave a cold car idling - although it was my Grandads advice 22 years ago when I had my first car a 1.0 Metro City X so maybe technology has moved on a bit (that car even had a choke!)

Key doesn't need to be in car after you've started it. I usually start mine then lock it while it defrosts.