Using demisters without heating

Mihir

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Wanted to check if there is a way to use the front demistifier without turning the heating on? The reason I ask is the rear demistifier can be used on its own without the heating turned on. I assume it uses the 12V battery for the operation as I do not see the change in range when its turned on. But whenever we start the front one, it always starts the heating(set at auto) by default. Can it not work without heating like the rear ones do? Do the front ones also use 12V battery or HV batteries?(Heating does use the HV, its clear from the range difference once heating is turned on). I am using RainX products for defogging etc. But wanted to learn/understand if this was possible to control/manage it from within.

There may be science behind it too but any ideas or inputs will be useful behind the understanding of it all.
 

Kithmo

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Unfortunately no, the front screen is cleared by the fan and heat from the HVAC system which uses the HV battery.
I do miss my 12v electric Quickclear windscreens I had on the Fords, these would be ideal for EVs.
 

N2STY

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You could try a aftermarket 12v one it would not kill the hv battery?
I see they do 12v heated blankets as well
 

Alb

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The amount of energy consumed in the demisting mode is fairly trivial because you only need to have it engaged for a couple of minutes at most.
 

Gadget Geek

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You could always try a wipe on glass treatment. There are plenty out there, some work well and others . . .
 

Mihir

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Why do you not want the heating on? If the screen is misted then use the demister!
On a long journey and a rainy day, the rear demistifiers are on most of the time and it does not affect the range either. I use heated seats which gives me the warmth. So I do not necessary want to use the heater all the time when I want the demistifier on( And heating reduces the range when on). More than the range its starting and stopping for a few minutes on a long journey. I'd rather have it on most times like the rear. Since the rear works on 12V, I was just wondering if there was a way to make the front ones work on the 12V too without the heating.
 

drmcw

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Sounds like you're worrying about range which implies you've bought the wrong car for your use cases. You should be able to use the car like you would an ICE car. If the front window fogs I just hit the demist button until it clears.
 

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Ford has the ownership for patents on front screen heater wiring. When they owned Jaguar that technology was brought across, and remains there now.

As such, the blower and heater needs to be turned on to clear the front screen.
 

N2STY

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It's a shame you can get heated front screens but I bleave ford own the Patent it would be the perfect solution

As I type it gets mentioned 😁
 

Gadget Geek

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Wanted to check if there is a way to use the front demistifier without turning the heating on? The reason I ask is the rear demistifier can be used on its own without the heating turned on. I assume it uses the 12V battery for the operation as I do not see the change in range when its turned on. But whenever we start the front one, it always starts the heating(set at auto) by default. Can it not work without heating like the rear ones do? Do the front ones also use 12V battery or HV batteries?(Heating does use the HV, its clear from the range difference once heating is turned on). I am using RainX products for defogging etc. But wanted to learn/understand if this was possible to control/manage it from within.

There may be science behind it too but any ideas or inputs will be useful behind the understanding of it all.
 

drmcw

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Maybe I'm flogging a dead horse here but 12V devices will provide maybe hundreds of Watts whereas the car heater can provide kilowatts of heat. All the systems are ultimately powered by the main battery so cut out the inefficient 12v middleman and use the heater to clear a windscreen efficiently and quickly!
 

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BarryH

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You could try a aftermarket 12v one it would not kill the hv battery?
I see they do 12v heated blankets as well
Whether the actual heating element is Low Voltage 12v or High Voltage 456v it matters very little it all comes from the same place ultimately that's the power you put into the HV battery, doesn't it? The 12v battery doesn't top itself up by magic. When you are in the car with it turned on the 12v battery is kept topped up by the inverter powered from the HV Battery. The time you run it for is very minimal on the whole because it is so efficient combining as it does the AC to dry the air and the heater to warm the air. Personally, I find it works best if you also turn the heat knob to the maximum setting and by the time I've walked around the car and used a rubber squidgy to clear condensation off the outside of both front door windows my screen is clear on the inside.

I'm not frightened of turning on the AC in winter either especially in the winter on a rainy day and this seems to have absolutely no noticeable impact on the range as the tinny motor used in the MG's AC compressor is so efficient so consequently, I've never suffered from the steamed-up windows that many people comment about on this forum - I guess the way I use the HVAC I have a drier car. Also by using the AC in conjunction with the heater rather than the heater alone (after the initial blast) I only ever need the heater on the mid setting which saves more power than the heater alone at a high setting to keep the car demisted.

What do others think the explanation might be?
 

drmcw

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Whether the actual heating element is Low Voltage 12v or High Voltage 456v it matters very little it all comes from the same place ultimately that's the power you put into the HV battery, doesn't it? The 12v battery doesn't top itself up by magic. When you are in the car with it turned on the 12v battery is kept topped up by the inverter powered from the HV Battery. The time you run it for is very minimal on the whole because it is so efficient combining as it does the AC to dry the air and the heater to warm the air. Personally, I find it works best if you also turn the heat knob to the maximum setting and by the time I've walked around the car and used a rubber squidgy to clear condensation off the outside of both front door windows my screen is clear on the inside.

I'm not frightened of turning on the AC in winter either especially in the winter on a rainy day and this seems to have absolutely no noticeable impact on the range as the tinny motor used in the MG's AC compressor is so efficient so consequently, I've never suffered from the steamed-up windows that many people comment about on this forum - I guess the way I use the HVAC I have a drier car. Also by using the AC in conjunction with the heater rather than the heater alone (after the initial blast) I only ever need the heater on the mid setting which saves more power than the heater alone at a high setting to keep the car demisted.

What do others think the explanation might be?
Same for the leaf, I just use it all the time. If you are worried about range then just dropping your speed will save you far more than turning off the heating/AC.
 

Kithmo

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I now have 3 x 1kg and two smaller car dehumidifier bags in the car and have cleaned the interior and exterior of all the windows with Rain-X window cleaner and have virtually no misting up. I don't have to use the demister as I used to on rainy days, I just set both the heat and fan to 3 blobs to keep it clear if it's a bit cold.
 

JCFlippen

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Whether the actual heating element is Low Voltage 12v or High Voltage 456v it matters very little it all comes from the same place ultimately that's the power you put into the HV battery, doesn't it? The 12v battery doesn't top itself up by magic. When you are in the car with it turned on the 12v battery is kept topped up by the inverter powered from the HV Battery. The time you run it for is very minimal on the whole because it is so efficient combining as it does the AC to dry the air and the heater to warm the air. Personally, I find it works best if you also turn the heat knob to the maximum setting and by the time I've walked around the car and used a rubber squidgy to clear condensation off the outside of both front door windows my screen is clear on the inside.

I'm not frightened of turning on the AC in winter either especially in the winter on a rainy day and this seems to have absolutely no noticeable impact on the range as the tinny motor used in the MG's AC compressor is so efficient so consequently, I've never suffered from the steamed-up windows that many people comment about on this forum - I guess the way I use the HVAC I have a drier car. Also by using the AC in conjunction with the heater rather than the heater alone (after the initial blast) I only ever need the heater on the mid setting which saves more power than the heater alone at a high setting to keep the car demisted.

What do others think the explanation might be?
I have always used air con all year round in my past ICE cars and also in the ZS EV Gen1. Misting up is not a problem but I do use an Amazon Silica Gel pack to keep condensation down overnight.
 

Tim Green

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I always use the front Demi’s tee button if the screen fogs. The interesting thing is that it turns on the air on and the blower at full power. BUT you can turn the blower down to minimum so is a useful way to have heater and air on on at the same time. I haven’t managed to find any other way.
 
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