Hi guys am I correct in thinking the heated front screen won’t work if the battery is not fully charged like the stop /start feature 

2013 ecoboost petrol 

cheers 

It’s not as sensitive as stop start. It will operate when stop start will not but yes if the battery is too low then the heated screens won’t work. It doesn’t need the battery to be fully charged though. 

As Alex has said it's not as sensitive as Stop/Start, but if the state of charge is less than 70% the front screen will not operate.

Thanks guys 

i thought it was broke but as I do around 40 miles a week it must be low charge 👍

on my older Mk2 you can feel and hear the car react to the button - it pulls major current - which seems odd if you see the small wires

9 hours ago, unofix said:

if the state of charge is less than 70% the front screen will not operate

Isn't this just utterly ridiculous? A vital safety feature disabled when surely the alternator must have the capacity to power it and still have some reserve to charge the battery. What are they thinking?

8 minutes ago, mjt said:

when surely the alternator must have the capacity to power it

but just think of all those emissions it would cause. we have to save the dolphins @StephenFord has told me 🤣 and he got that information direct from a Tree Hugger 🤣😂🤣 

1 hour ago, mjt said:

Isn't this just utterly ridiculous? A vital safety feature disabled when surely the alternator must have the capacity to power it and still have some reserve to charge the battery. What are they thinking?

It wouldn’t surprise me if the alternator can’t put out that much current at idle. 
 

It’s also not a safety feature it’s a convenience feature. It’s not standard on all models. Before Fords patent ran out it wasn’t on any other make. You can just use the blowers it will take longer though. 

I was also under the impression it looked at state of battery charge. But on my 2007 fiesta 1.6tdci which I had for 9 years on original battery the heated front screen never stopped working so it couldn’t be very sensitive to battery state on that car. I thought it might be more sensitive on a diesel due to glow plugs taking a lot of power also. I don’t know if the percentage of battery state of health is programmed differently on different models / years.    Edit: actually thinking about this more maybe it’s different on cars with bms. 

On later models all high draw equipment (stop/start, heated screen etc) will only work if the state of charge is high enough. However, the default is to have a target of 80% state of charge for the battery and after that the alternator free-wheels. The system also limits the amount of current available to charge the battery. This is all in the name of emissions as the alternator creates a drag when charging. The trouble is, the system then shuts off the high-draw equipment if the state of charge drops too low. The consequence is that in cold weather, or with short journeys, the state of charge never reaches the target and things stop working. My wife had an old Fiesta without this system and the heated screen worked perfectly in all weathers. My nice shiny modern S-Max refused to clear the front screen in the first frost it encountered. However, with Forscan, I have changed the Target State Of Charge from 80% to 90% and everything now works all the time.

11 hours ago, alexp999 said:

It wouldn’t surprise me if the alternator can’t put out that much current at idle.

That shouldn't prevent it being re-enabled once the alternator reaches a speed where it can sustain it.

11 hours ago, alexp999 said:

It’s also not a safety feature it’s a convenience feature.  You can just use the blowers it will take longer though

I can't agree. The ability to rapidly clear the screen is an important additional safety feature.

5 hours ago, mjt said:

 

I can't agree. The ability to rapidly clear the screen is an important additional safety feature.

I think the other guy covered it, its a convenience feature.... you can stand in the cold, car locked, engine off, and get all the windows clean, then drive away

with global warming its 3 days a year you get ice on the screen, its not 7 months solid

2 hours ago, Botus said:

...with global warming its 3 days a year you get ice on the screen, its not 7 months solid

Ironic that, 'global warming', and we're complaining about an icy windscreen  🤣

Dunno about you but our screens are already frozen tonight, and were for the last 2 nights as well...I wish 3 days was all we had.  Heated screen is the main thing I miss from Ford's!