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vince_13
can anyone tell me why the heated front screen is on a timer? in comparison to the rear heated window where you turn it on and off, the front screen will go off after a length of time
Lenny
[quote name='vince_13' timestamp='1358884234' post='229328']
can anyone tell me why the heated front screen is on a timer? in comparison to the rear heated window where you turn it on and off, the front screen will go off after a length of time
[/quote]
The heated windscreen is more powerfull than the rear demister.
It is on a thermostat which trips off to prevent overheating
It also trips off to save your car battery and fuel consumption. Notice how your headlights dim when heated windscreen is active.
It draws 20amps of power from the car.

The heated windscreen is two elements fed seperatly through two fuses,
One element for passenger side and one for drivers side,
If a fuse ever blows you will clearly see the divide in elements as one side will be clear and othe frosty.
martyntdci
Ever since my alternator packed in and also had electrical gremlins at same time. I've not used the front screen. As lenny said it draws loads of power from every where and tbh imo it car.nt be good....

This is my opinion tho.
..
k13r4n
[quote name='Lenny' timestamp='1358886571' post='229341']

The heated windscreen is more powerfull than the rear demister.
It is on a thermostat which trips off to prevent overheating
It also trips off to save your car battery and fuel consumption. Notice how your headlights dim when heated windscreen is active.
It draws 20amps of power from the car.

The heated windscreen is two elements fed seperatly through two fuses,
One element for passenger side and one for drivers side,
If a fuse ever blows you will clearly see the divide in elements as one side will be clear and othe frosty.
[/quote]

+1 agree here lenny has it bang on also note
when your electrics are on your rear window will work whereas your front won't
TDCiST
Your rear should be on a timer also... I believe all focus have this now (please correct me if I'm wrong).

I think it's set to anywhere between 10 an 12 minutes and can be changed via IDS or that Russian software...

Whereas the front is timed at 4 minutes (I believe) but you rarely need more than this!
Stoney871
My rear demister switches off automatically.
vince_13
wow thanks guys, alot of info there i didnt know, yeh leeny i had noticed that, i always thought it was because i was on tick over, so dim the lights to divert the current to more necessary functions, no idea it was 20amps

i hadnt tried it with the engine off either but worth knowing
Andy H Dibley
[quote name='vince_13' timestamp='1358924790' post='229477']
wow thanks guys, alot of info there i didnt know, yeh leeny i had noticed that, i always thought it was because i was on tick over, so dim the lights to divert the current to more necessary functions, no idea it was 20amps

i hadnt tried it with the engine off either but worth knowing
[/quote]

Don't believe you can use either the front or the rear with the engine off.

If you think of them as effectively shorts across the the battery, that's what they are. The front is made up of a lot more 'elements' than the rear. If you look close enough they're spaced about 2mm apart and cover the entire screen. That's a lot of elements.

Top tip. If your car is snow covered, clean the door area, open up, start the car, turn on the heated screens (mine auto brings on the heated front and rear screens), then set about getting the snow off, leaving the windscreens till last. Then after a minute or two, then entire screen of snow will just slide off. The ice underneath will have melted and brushing away the covering of snow will leave you with a clear and clean screen to start driving.
artscot79
you cant switch the front on without the car running the car wont allow you to since it draws such a high current the car prevents it from being activated till the car is started even then if it detects a low battery it wont allow it to switch on great way to tell if youre batteries toast the rear is set to 15mins and switches off itself the front is as said 4 minutes trust me even with mega thick ice you dont even need 4 minutes and from experience just setting the aircon to hot and windscreen does just as good a job of melting the ice
whitelightning
Hi, can i join the "heated debate" ha see what i did there....anyway,

my front screen demists with a 2 inch line down the centre that remains un heated, like a focus splitscreen if you will?
Any ideas? No damage on screen stone chips etc. I looks to be the original screen too.

seems odd
thoughts.........

thanks
artscot79
the centre is the last part to heat up as it heats from the sides inwards if after 5 mins which is the max time the heater is on it still hasnt cleared then its likely the centre wires are broken though i doubt it the centre just takes a bit longer than the rest thats all
whitelightning
Thanks. hmmmm it doesnt get that long because it gets switched off.........lol!!! when i switch on again still wont clear, wires then?
Cheers
artscot79
Sounds like the wires if its just the centre thay doesnt clear but both sides do if you look close enough you may see the breaks in the wires unfortunately these cant be fixed the only other thing i can think of is the plugs under the scuttle need cleaned but that means exposing the pollen filter and i wouldnt do that till i needed to
whitelightning
Thanks, yeah that old pollen filter trim fight eh? Big jollies getting that out in one piece!
vince_13
heres a question, this morning on the motorway going along at 65 bout 2900rpm i put the heated front screen on and noticed the headlights dip, surely if the engine is running at 2900rpm therefore turning the alternator, surely there would be enough power being supplied for the lights to be on and the front screen on?
stef123
[quote name='vince_13' timestamp='1360257713' post='233994']
heres a question, this morning on the motorway going along at 65 bout 2900rpm i put the heated front screen on and noticed the headlights dip, surely if the engine is running at 2900rpm therefore turning the alternator, surely there would be enough power being supplied for the lights to be on and the front screen on?
[/quote]

Any heated screens i have come across are fed from 2x 30 or 40 amp fuses (cant remember which), so even with good revs its still alot of power for the alternator to supply. the headlights alone without any other lights will be drawing around 9 amps
alexp999
Don't forget as well, the alternator puts all its power through the battery first to provide a stable voltage and everything is still sharing that power through the battery.
stef123
[quote name='alexp999' timestamp='1360260658' post='234004']
Don't forget as well, the alternator puts all its power through the battery first to provide a stable voltage and everything is still sharing that power through the battery.
[/quote]

the fuse-boxes are fed from the same point where the alternator connects to the battery so the battery only really supplies more power where the alternator cant provide it.
voltage stabilisation is done at the regulator

just my 2p's worth
alexp999
Ah ok, I thought the alternator passed the power across the battery at higher voltage then the battery provides a stable 12V.

Otherwise the entire electrical system would be running higher than 12V?
stef123
[quote name='alexp999' timestamp='1360261237' post='234010']
Ah ok, I thought the alternator passed the power across the battery at higher voltage then the battery provides a stable 12V.

[b]Otherwise the entire electrical system would be running higher than 12V?[/b]
[/quote]

correct, the alternator produces an a/c voltage, which is then turned to dc (by a rectifier) and at a stable voltage by the regulator (the black bit on the end of the alternator)

so yes the electrical system does run at a bit more that 12v
Stoney871
The system usually puts out about 14v and as stated the rectifier makes sure that the voltage is stable then the GEM makes sure the right amperage gets to the right parts.
Nathan_M
If its the same as my MK6 Fiesta you get 4 minutes on the front screen, although it doesn't seem to affect my motor as it sits at a high idle when its cold and this seems to counteract the power draw from the heater in the Front and rear windows, if you have the interior fan on 4 as well you will notice that it sounds more like position 2 when you have it all on, i would have thought that even at idle the alternator would have enough output to power the engine and all internal electronics by design they must expect people to use everything at once.
vince_13
[quote name='stef123' timestamp='1360261551' post='234014']
correct, the alternator produces an a/c voltage, which is then turned to dc (by a rectifier)[/quote]

didn't know that, i was under the impression they output dc, is it rectified at the alternator then?

i thought the same Nathan, i suppose though if the alternators job is to keep the supply of average 12V constant and stable, when the heater is on it will draw on the battery (like any other device) therefore leaving the alternator to catch up, (if that makes sense)
stef123
[quote name='vince_13' timestamp='1360268303' post='234053']
didn't know that, i was under the impression they output dc, is it rectified at the alternator then?

i thought the same Nathan, i suppose though if the alternators job is to keep the supply of average 12V constant and stable, when the heater is on it will draw on the battery (like any other device) therefore leaving the alternator to catch up, (if that makes sense)
[/quote]

the alternator on its on will produce ac (no rectifier/regulator), its then rectified to dc and then regulated to 14.4v (the actual voltage is determined by the ecu)
the regulator and rectifier are all part of the alternator

the alternator cannot cope with all electrical demand, and more so as the alternator heats up so the battery is what supplies the power required - hence why you get dimming lights and the fan slows down (the voltage has dropped because the alternator cannot supply anymore juice)
vince_13
thanks stef123 learnt something new :)
whitelightning
As long as the engine is running the alternator charges and runs the electrics as a 12v system. It not a dynamo...the lights don't dim when you slow down ( i hope)! Or get brighter when you speed up..........The front screen takes a huge whack of power as do headlights, we have to look after these old alternators especially when you hook up two amps and a sub and 4 6x9 speakers!!
vince_13
[quote name='whitelightning' timestamp='1361288441' post='237051'] we have to look after these old alternators especially when you hook up two amps and a sub and 4 6x9 speakers!!
[/quote]

haha dont i know it, those days are long gone :P played havoc with my old fiesta alternators, 2 alternators and 3 batteries in 6 months is not good
Lenny
[quote name='whitelightning' timestamp='1361288441' post='237051']
As long as the engine is running the alternator charges and runs the electrics as a 12v system. It not a dynamo...the lights don't dim when you slow down ( i hope)! Or get brighter when you speed up..........The front screen takes a huge whack of power as do headlights, we have to look after these old alternators especially when you hook up two amps and a sub and 4 6x9 speakers!!
[/quote]
If you have an amp fitted in your motor you may like to purchase a pivot mega razin voltage stabiliser kit.
Its a series of capaciters which supplys more instant power resulting in consistant voltage supply to your electrics, with no strain or draw being put on your altinator.

Beware of cheap ebay imitations they don't work, I've bought two replicas on ebay 100% crap.
Buy only from the offical pivot website.

[IMG]http://i575.photobucket.com/albums/ss192/lennymanwoods/pivot-mega-raizin-voltage-stabilizer-volt-meter-100-japan-1010-04-didomydude8.jpg[/IMG]
[IMG]http://i575.photobucket.com/albums/ss192/lennymanwoods/Mega3.jpg[/IMG]
[IMG]http://i575.photobucket.com/albums/ss192/lennymanwoods/Mega5.jpg[/IMG]
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[IMG]http://i575.photobucket.com/albums/ss192/lennymanwoods/MTC_7653.jpg[/IMG]


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