alaattin Posted October 24, 2021 Share Posted October 24, 2021 Hello, I have 2011 ford fiesta 1.4 96ps. I changed alternator and battery but still reading 13v. after I changed voltage regulator, I can read 14v but the car is battery light is on. I couldn't fix this problem. any one help me ? Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 I think you have shorted something out. You changed the alternator then the voltage regulator on the alternator, yes? If the light is on, that could be for a number of reasons but I would first check all the earths to the engine are intact and well tightened before strongly suspecting that the new regulator is short. Quote Link to comment Share on other sites More sharing options...
alaattin Posted October 24, 2021 Author Share Posted October 24, 2021 13 minutes ago, anon said: I think you have shorted something out. You changed the alternator then the voltage regulator on the alternator, yes? If the light is on, that could be for a number of reasons but I would first check all the earths to the engine are intact and well tightened before strongly suspecting that the new regulator is short. I actually bought the car a week ago. It didn't start and I changed the battery. then it was necessary to remove the alternator 4 times. First of all, I just changed the connector, I couldn't get any results, it was still charging 12.9-13v. Secondly, I connected a different brand connector and reached the value of 14v, but the battery warning lamp inside the vehicle came on. I changed the original alternator for the 3rd time, this time the lamp was dead, but the vehicle was charging as 13v. Finally I installed the old alternator and I'm still looking for what caused the problem. (it drops to 12.9 when I turn on the headlights and air conditioner) Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 What do you mean by the connector? are you talking about a plastic and metal object with a flat terminal on it that comes off the back of the alternator with a screw or two? Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 While I am waiting for the answer to that one, does the battery go flat overnight? I have a theory but I want to make sure of a few things to ensure that any advice I give you can be backed up with a reasonable expectation that it might work. Quote Link to comment Share on other sites More sharing options...
alaattin Posted October 24, 2021 Author Share Posted October 24, 2021 8 minutes ago, anon said: What do you mean by the connector? are you talking about a plastic and metal object with a flat terminal on it that comes off the back of the alternator with a screw or two? Yes, it is meaning voltage regulator. Quote Link to comment Share on other sites More sharing options...
alaattin Posted October 24, 2021 Author Share Posted October 24, 2021 8 minutes ago, anon said: While I am waiting for the answer to that one, does the battery go flat overnight? I have a theory but I want to make sure of a few things to ensure that any advice I give you can be backed up with a reasonable expectation that it might work. No, i can start every morning and it is work. Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 I think that the alternator may be providing current through only two of its three phases. I reckon the diode pack is faulty so it makes some charge but is not making what it should. You need a new alternator. One that works. Quote Link to comment Share on other sites More sharing options...
alaattin Posted October 24, 2021 Author Share Posted October 24, 2021 6 minutes ago, anon said: I think that the alternator may be providing current through only two of its three phases. I reckon the diode pack is faulty so it makes some charge but is not making what it should. You need a new alternator. One that works. I replaced with new alternator but i took same result. Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 That makes little sense. Is there power to the voltage regulator ? (battery voltage should be present with ignition on.) Quote Link to comment Share on other sites More sharing options...
Pep943 Posted October 24, 2021 Share Posted October 24, 2021 Hi I am having the same issue, battery warning light is on, new battery 3 months ago no problems then last week warning light, car has always started even after a few days, changed the alternator for second hand one but still the same, any advise to remedy v welcome Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 Then take it to a garage Pep because your last guess was wrong and costly. 1 Quote Link to comment Share on other sites More sharing options...
unofix Posted October 24, 2021 Share Posted October 24, 2021 Could you just imagine carnage if people tackeled surgery the way that some try car repairs 🤣 1 Quote Link to comment Share on other sites More sharing options...
anon Posted October 24, 2021 Share Posted October 24, 2021 They do. Have you never heard of the Kardashians? Quote Link to comment Share on other sites More sharing options...
Stuart.W Posted November 1, 2021 Share Posted November 1, 2021 Hi all, I'm here after googling the same issue that I believe alaattin has. My Gran's car is 2009 Fiesta Edge, 1.4 Petrol, Auto', 52K miles, owned from new, serviced by myself. Last week the battery went flat after never struggling to start since 2.5 years ago when I put a new (first replacement) battery on, Bosch S4 calcium. I believe the car is unable to charge up adequately due to low charging voltage and after every use the battery voltage decreases slightly until it won't start. Charged battery over night and checked voltage at 12.8volts, started car, drove 6 miles to get hot, checked hot idle voltage at 13.6volts with no load and 13.3volts with high load. After a few more short journeys its now at 13.0v / 12.7v respectively. I removed plug from alternator that goes to ECU and after 10 seconds, 14v showing so I assume the connector and loom are not at fault, perhaps this indicates the alternator is also ok but my ST180 will charge at 14.6v after a warm start. Changed battery for identical Bosch S4 from wife's KA which charges at 14v and starts perfectly but made no difference to Fiesta low charge voltage of 13v, wasn't expecting anything but I could check it for free, so I did. I can only think of replacing the alternator but it seems many people have done this and still have the same problem. I have FORScan (limited version), I am yet to check error codes and temperature sensors. It seems a few people online have seen generator error codes but have not gone away after replacing the alternator, it seems the most common cause for low voltage charging is non calcium battery type or faulty signal wire/loom which I'm sure I don't have. I have not found anyone who has had to replace the ECU or a sensor to resolve this issue, the thought of taking it to Fords and my Gran paying £1000's isn't appealing..... Can anyone suggest anything to try please? Quote Link to comment Share on other sites More sharing options...
anon Posted November 1, 2021 Share Posted November 1, 2021 A word of warning. Disconnecting anything from an ECU is risky. They can take readings base on what they cannot see and start turning off systems for indeterminate periods of time. I think that code readers are of no use for this particular problem because they will be unable to sense the place where the voltage drops. I strongly suspect that the car's earth returns are aged and resistive. I would try fitting a couple of new earth straps, where they are currently fitted to the car. They can easily age through heating over ten years of starting a car and become so resistive as to soak up half a Volt or so, not the 30 milliVolts that I would normally expect. It is inexpensive to do, will not take all day and can not do any harm. They can be the braid type from your local accessory shop. Those will be much cheaper and stouter than those supplied by Ford. Quote Link to comment Share on other sites More sharing options...
anon Posted November 1, 2021 Share Posted November 1, 2021 If you have a good meter, measure the drop from the cylinder head to the battery earth and if it is greater than 200mV when starting the engine- bingo! Quote Link to comment Share on other sites More sharing options...
Stuart.W Posted November 2, 2021 Share Posted November 2, 2021 Thank you anon, that's great advice. The front heated screen was replaced 9 days ago and I thought that they had done something because the car was perfect before and since then it's had this fault. The negative earth strap from battery to front left chassis suspension turret didn't look or feel as new when I moved it out of the way (whilst still attached to the chassis) and Autoglass would have disturbed this too so thank you I'm off to check that and the above. Quote Link to comment Share on other sites More sharing options...
anon Posted November 2, 2021 Share Posted November 2, 2021 A couple of questions. A new heated screen adds another dimension. Was the heater working before the screen was changed? I would try the charging system performance with the windscreen fuse out just in case it has either been wired up wrong or the relay has welded shut and the windscreen is on all the time. Quote Link to comment Share on other sites More sharing options...
Stuart.W Posted November 4, 2021 Share Posted November 4, 2021 Thanks anon, yes the windscreen heater was working both before and after replacement. I have an accurate but basic multimeter so have just measured the voltage difference between battery terminals and then between cylinder head and positive terminal, its only a 20mv drop when the engine runs at both 13v and 14v (yes, it has since been back up to 14v, see below). On Tuesday morning the car sat at 12.01v before starting perfectly in 6c? temp, it gradually rose to 14.3v within a few seconds, I had moved the main earth strap to feel the flex at the chassis end but I don't think this had anything to do with seeing 14v charging. I then did 70 miles and tested the charging throughout the day, after 6 miles with a short Motorway sprint the charging was 13.7v, after a further 27miles it was still at 13.7v. Did 4 miles around town and 13.1v charging. Left car for 5 hours, cold engine, 12.3v before starting and idled with 13.1v, putting a jump lead across the main earth strap made no real difference, <10mv. Yesterday morning the car sat at 12.22v and gradually rose to 13.1v after starting well first time, I can only assume that this is how the Ford smart charge system is designed to work? I think (and hope) that the car's battery had been drained whilst the windscreen was replaced and for some reason didn't charge up during the one short journey it had since then and before the next time it was used when the battery was so flat that the ignition lights didn't even come on and yet nothing had been left on to drain it to our knowledge. This makes no sense to me as the alternator should have put more charge in unless the smart charge system doesn't work below a certain voltage? She didn't see any warning (battery) light come on but I doubt she would have noticed. It doesn't give me confidence when I don't know exacty what happened and why but the car runs perfectly, starts first time and strongly. I will definitely post here if the battery goes flat again and wish alaattin luck in sorting their car issue. Anon, thank you, I very much appreciate your advice on what else there is to look out for, I wanted to ask what sort of meter and technique would I require for measuring the drop between the cylinder head and battery earth when starting the car please? Quote Link to comment Share on other sites More sharing options...
anon Posted November 4, 2021 Share Posted November 4, 2021 If you are seeing an increased voltage after a run and that voltage does not decay after an hour to the initial voltage then the system is charging. I have the luxury of good and expensive test gear but you have used what you have methodically which is fine, your 20 mV drop looks good and moving the earth has brought you back to the 14 volt range. I would simply replace the earth strap as that was what you moved before you got. back to 14.3V. Quote Link to comment Share on other sites More sharing options...
Stuart.W Posted November 10, 2021 Share Posted November 10, 2021 Many thanks 👋, I hope anyone else that sees lower than normal conventional 'old school' (14+) voltage has a smart charge system still functioning correctly and not a fault elsewhere causing continual flat batteries, my gran's Fiesta has been faultless since her mystery flat battery. Quote Link to comment Share on other sites More sharing options...
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