Heated windscreen drawing too much current
Discussion
I have a MkII Focus ST and the heated windscreen was recently replaced with a Pilkington Glass model.
I've had problems with the battery recently and a local garage diagnosed that when the front heated windscreen is on the voltage output from the battery dips below 12 volts and keep on dipping. You can see this as the lights dim and the heater blower speed decreases.
The battery itself is fine according to the test equipment, however if I don't drive the car for a few days I have come out to a dead battery - could the above problem be draining it when the car is off?
Has anyones seen this before? I've had the windscreen wiring and earths checked and they're fine. The only thing it could be is the Windscreen itself being faulty.
I've had problems with the battery recently and a local garage diagnosed that when the front heated windscreen is on the voltage output from the battery dips below 12 volts and keep on dipping. You can see this as the lights dim and the heater blower speed decreases.
The battery itself is fine according to the test equipment, however if I don't drive the car for a few days I have come out to a dead battery - could the above problem be draining it when the car is off?
Has anyones seen this before? I've had the windscreen wiring and earths checked and they're fine. The only thing it could be is the Windscreen itself being faulty.
Unlikely as there is no power to the heated window when the car is switched off. Try removing the fuse for the heated window and see if the battery problem goes away. I have had a similar problem recently where the battery voltage dropped below the threshold required to operate the starter. It would seem that the current drain from a small fridge in the boot is sufficient to prevent the battery from reaching full charge again after starting and just sitting with the first position ignition on for a few minutes is enough to prevent starting again. I have unplugged the fridge and no further problem so far.
The odd thing is that I noticed "Power steering failure" appearing on the display on startup just after the windscreen was fitted.
Once the car had started, the warning was cleared and the steering was fine. I seem to only get this happen when the car hasn't recently been driven. If I charge the battery I do not get this message either.
It appears that there is something up with the windscreen. On the diagnostic the volts just kept dropping when the screen was active, and I've had the car nearly stall when the windscreen was on.
Once the car had started, the warning was cleared and the steering was fine. I seem to only get this happen when the car hasn't recently been driven. If I charge the battery I do not get this message either.
It appears that there is something up with the windscreen. On the diagnostic the volts just kept dropping when the screen was active, and I've had the car nearly stall when the windscreen was on.
My heated windscreen is fused to 60 amps each side, so in theory it could draw 120 amps.. When I turn it on I definitely hear the strain, all the lights dip and the fan slows down. If I stall or even nearly stall the windscreen turns off automatically.
I digress, a slow battery drain is not likely to be the windscreen at all. How old is the battery? Is the dashboard turning off after a short time, or is it staying on?
I digress, a slow battery drain is not likely to be the windscreen at all. How old is the battery? Is the dashboard turning off after a short time, or is it staying on?
Peanut Gallery said:
My heated windscreen is fused to 60 amps each side, so in theory it could draw 120 amps.. When I turn it on I definitely hear the strain, all the lights dip and the fan slows down. If I stall or even nearly stall the windscreen turns off automatically.
I digress, a slow battery drain is not likely to be the windscreen at all. How old is the battery? Is the dashboard turning off after a short time, or is it staying on?
Battery is five years old. The battery test equipment said it was still good.I digress, a slow battery drain is not likely to be the windscreen at all. How old is the battery? Is the dashboard turning off after a short time, or is it staying on?
No, the dashboard goes off.
Peanut Gallery said:
Cheers!
Confirm when you turn the windscreen on everything takes the load, but when you turn it off everything bounces back to normal?
5 years is still young, but not out of the question I am afraid. (3 batteries in a row have died at 13 months in a previous car)
Yep, that's correct.Confirm when you turn the windscreen on everything takes the load, but when you turn it off everything bounces back to normal?
5 years is still young, but not out of the question I am afraid. (3 batteries in a row have died at 13 months in a previous car)
I've had my battery tested at two different garages and they both said it was fine but undercharged. For the most recent one I had given it a full charge with trickle charger two days before, and the day before had done a 90 mile round trip.
The guy at the most recent garage seemed absolutely convinced that the voltage readout shouldn't have been dropping like that.
This is interesting... I've charged the battery up using my CTEK charger and the charger claims it is fully charged.
However, turning off the charger and checking the battery with a multimeter shows a voltage of only 12.23 volts.
The table on http://www.aa1car.com/library/2003/us20310.htm says this is only a 50% charge. Does this indicate the battery needs changing?
However, turning off the charger and checking the battery with a multimeter shows a voltage of only 12.23 volts.
The table on http://www.aa1car.com/library/2003/us20310.htm says this is only a 50% charge. Does this indicate the battery needs changing?
I went to the on-board battery voltage reader in mine, rough numbers are about 14 when idling, no load. Turn on the windscreen, drops to 13.3 and stays there. Turn on everything else and it drops to about 10! (I mean everything else...)
What voltage are you getting when idling and no load?
What voltage are you getting when idling and no load?
stevensdrs said:
Your battery needs replacing, as does mine which is only holding a 50% charge.
I took it to a Ford garage that diagnosed the battery actually.Seems fine so far with the new battery, and from a quick test with the blowers the voltage now doesn't seem to drop when using the heated windscreen.
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