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Full Version: God Give Me Strenght,,, Alternator Advice!!!
Ford Owners Club - Ford Forums > Ford Models > Ford Focus Club
Mike77
Ok ppl, I'll try give you the short version. Tested the alternator the other day, and with engine on and ancillary's going, I can only get a reading of approx 11.5v max 12v auto spark said it was goosed. So swapped it yesterday, pain in the arse of a job, but then getting the same readings but also battery light was staying on. Took it off again, swapped it for another new one. This time no battery light, but only showing 11.6v when ancillary's running ? Is this how it should be ? It's driving me mad.

Figures as follows,
Engine off 12.3v
Engine on, nothing switched on 14-15v
Engine on, ancillary's running 11.5v

Don't know if its related but the dash info ie outside temp, distance to empty etc etc still playing up. Really hope someone can shed some light on this, regards, Mike.
Aaron111111
You should be seeing about 14.4v at the battery with engine running so you have an issue with maybe a bad earth or broken wire, maybe even a fuse blown if the alternstor circuit has one. (Not sure on the focus)
Aaron111111
Sorry didnt read the bottom of your post!!! However id still look at a bad earth or broken earth wire
Mike77
It is about 14.4 ish with engine on, but only until I switch on the heated screens, heaters lights etc, then it takes a dive to below 12v, not thinking it should drop so low,first car I've had with the smart charge system so not very clued up on it, and dont know the operating variants of the system.
artscot79
jesus do mechanics know bugger all with the engine idling the heated screen if you read the manual draws mega current which is why you shouldnt use it unless you need to with all that on the readings will drop as the screen is taking 3 times the amount of current as all the rest put together if you had used the accelerator to spin the alternator up youde have found the readings would climb with headlights and rear screen on is how it should be tested not with alll of it and the front screen its too much for the alternator to take at idle there was nothing wrong with youre original alternator it was working as it should be if the alternator was faulty the heated screen wont turn on at all youre supposed to use the heated screen and fan then switch off asap then use the rest mate i will bet a months wages if you take it to ford they will tell you the same
wish you had pm me first mate as you didnt need that alternator or the hassle fitting it in the first place
Mike77
I wasn't sure pal, so even took it to an auto electrician, and he said it was gone.... Was talking to my dad about it before I stating I wasn't sure the guy was right. I was jaust led to believe that anything below 14v with engine on and things running was bad. So just lights and rear screen... I'll try that and post results, thanks mate.
artscot79
yep the front screen uses the same power on its own as the rear screen headlights main beam indicators and radio together so you can see why all of it and the front screen would drop the readings with all that on if you rev the engine to 2500 rpm the reading would increase the alternator cant cope with that load running so slow it needs speeded up and most cars dont have heated front screens the auto electrician clearly didnt understand smartcharge as if the battery is near full charge and the electrolyte is hot then the alternator reduces the output automatically and can drop below 14v with all electrics off as the battery discharges the alternator increases the output to the battery to recharge it in the old days below 14 was bad but with fords smart charge its not uncommon
Mike77
Hi artscot, just tried again like you said, and the readings didn't drop as low, think with lights and rear heated it was 13.2v, lights & both heated screens was 12.4v then down to 11.9v with heaters on full blast too. Did try revving it earlier with everything on, and although it did raise, it was a very small one, from around 11.3 upwards slowly not getting up to 12v, bu only did it for about 30 seconds,,,, does that sound right? Thanks for your assistance, its much appreciated.
artscot79
Sounds about right to me the alternator cant cope with all the load however as the heated front is only for use when necessary it wasnt designed to be used while driving it will only stay on for 5mins max if i remember the rear screen is 25amp the front is 75amps just those 2 alone is 100amp add the lights at 25amp heater at 30 amps thats a lot to deal with rear screen and lights on the reading should drop and go up to 14.4 when revved as the revs drop the reading will drop just lights 14.3 even in mine if you switch headlights on and front screen watch the lights dio the more you add the harder it is for the alternator to cope what was the issue with the dials ?
Mike77
It's not the dials as such, just the computer display that shows the mileage, mpg outside temp etc,,, when I switch on, they have started randomly flicking through, and I have no control over it, pressing the button on the end of the indicator stalk or using the toddle switch has no effect and they continue to do their own thing, sometimes it will stop and be ok, others it will stop but which ever one it stops on its locked there ???
FOCA
[quote name='artscot79' timestamp='1355003296' post='220254']
jesus do mechanics know bugger all with the engine idling the heated screen if you read the manual draws mega current which is why you shouldnt use it unless you need to with all that on the readings will drop as the screen is taking 3 times the amount of current as all the rest put together if you had used the accelerator to spin the alternator up youde have found the readings would climb with headlights and rear screen on is how it should be tested not with alll of it and the front screen its too much for the alternator to take at idle there was nothing wrong with youre original alternator it was working as it should be if the alternator was faulty the heated screen wont turn on at all youre supposed to use the heated screen and fan then switch off asap then use the rest mate i will bet a months wages if you take it to ford they will tell you the same
wish you had pm me first mate as you didnt need that alternator or the hassle fitting it in the first place
[/quote]

+1 i was about to post similar info,

the smart charge system requires a silver calcium battery,

Usually drivers do not switch all their electrical stuff on at once and drive around at tickover, as artscot has said, the revs go up as you drive and the heated windscreen switches off after 5 minites and gives the battery a chance to recover from the energy removed by starting
Mike77
I replaced the battery a few weeks back, and it is a silver calcium one.
artscot79
Nowt to do with the battery or alternator thats a stalk issue the scroll mechanism on the stalk is on its way out ide get a second hand one and swap them over
Mike77
Just been on eBay looking, and they are roughly 25 quid, so think that will be my next step, all other functions work on there, indicators main beam etc, just nothing from the rocker switch or the button on the end. But it will work at random times... Thanks for you help artscot, took the car out earlier while connected to a battery tester, and its charging as it should be, so I'm gonna move on from that episode now lol.
artscot79
No worries many garages and even auto electricians know sod all about smart charge when its those types of things ford dealers are best they may be dearer but they save you money rather than spending cash on bits you dont need
jeebowhite
As arts said, most the time they just know how to read the words on a computer screen, its rediculous. As long as your engine only current is above 14v then the battery and alternator are fine, anything below that with any electrics running is expected. If you drop below 9 volts with electrics running you might be up the creak, but I cant see that being an issue.
Mike77
Yes, I now have a better understanding of the way these systems work, all is fine regarding the alternator now. So once again, thanks to all for the help :-)


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