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Discussion Starter #1
Hi everyone, first post so I hope I'm doing everything right! I've been searching for information on this 'problem' for weeks and can't seem to find a convincing answer.

OK so I've had the car (a 1.0 Ecoboost Focus, 2013, UK) for a few months and the first indication anything was wrong was Stop-Start wouldn't function. Not something which would bother me itself but I wanted to know why it wasn't working.

I did a bit of digging and found out a bit about how it's fussy about things like battery condition and voltage, so I waited until after I'd done a few long journeys and still nothing. Alternator seemed OK, producing just under 15v right after starting. I hooked it up to a battery charger (using post for ground, not battery terminal, as instructed by manual) and the battery would not go above about 12.32v despite hours of charging. OK so the battery is toast, I ordered and installed a replacement, 12.8v out of the box, did the BMS reset and Stop-Start starts working as expected.

However, after a few days the voltage was back down around 12.5v which had me concerned. My commute to work is only a few miles but still it should be plenty of time to replenish the energy taken by the starter motor.

I once again checked alternator voltage after starting which seemed fine, and responded to increased load such as lights, heated windscreen, etc. However I waited for a minute or so and the voltage dropped right down to ~12.3v. It still seemed to respond to load though, e.g. it initially dropped after adding load but came back up to the 12.3v mark as though the regulator is just avoiding charging the battery.

The problem is, today the battery is now back to 12.2v despite fully charging it again last weekend and I'm concerned it could be something about the smart charging system not allowing the battery to receive a full charge, and could be causing premature wear/sulfation. I've not noticed any battery warning lights, and were it not for checking voltages, the car has given no indication anything is wrong.

Is this behaviour normal?

Many thanks for reading, feel free to ask for any further details, I've just included what I think is relevant.
 

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Discussion Starter #3
Thanks for your reply, I've had a read through that PDF. That and a few other sources have mentioned that optimum 80% value, but in my case it seems to be consistently a fair bit below that, 50-60% going by battery voltage (I know it's not a perfect indicator), and seemingly not continuously charging the battery even when it's in this state?

I know I'm probably over-thinking it, I just don't want to be going through batteries if something isn't right.

As an aside, is it harmless (to BMS for example) to give the battery a full charge occasionally?
 

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A new battery dropping to 12.2 volts is NOT normal. Regardless of what the charging system does minute to minute the battery should be staying toward the higher number (12.8) if getting the proper amount of charge. A new one can drop a little as it settles in but 12.2? No way.
 

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Discussion Starter #5
That's pretty much my thoughts. Any suggestions on what it could be/what to do about it?

The alternator *seems* OK, in that it can output a good charging voltage at times and there are no warning lights/messages. Is there a way to reset the charging system for example?
 

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Discussion Starter #6
Just to update, there are no DTCs showing on forscan and battery age is (correctly) showing at 20 days. However it's also showing as 80% charge for this voltage.

Does anyone know why that would happen?

Thanks.
 

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From the .pdf.............

'Conventional charging aims to charge the battery to the highest possible levels. During this process the battery temperature is monitored and the battery must not be overcharged.

By comparison, Smart Regenerative Charging uses the information from the battery monitoring sensor to maintain the battery at a calibrated state of charge (approx. 80%) at all times. This means that the battery has a certain amount of extra charging capacity at all times.'

That at face value and if true has to be one of the dumbest things I have ever heard of. Essentially saying the battery never charges up fully and of what POSSIBLE use is 'capacity' if one is NOT going to use it by default. All it does is put the battery 20% closer to a fail, it defeats the entire idea of current held in reserve. It IS a 'storage' battery after all. Now kept free of 20% of its' potential storage. How utterly lame.

Some idiot engineer probably has a reason for it and likely involves more trips to the dealer as a result. Probably to save the alts from as much failure since they apparently are not smart enough to design them to last under heat, the big problem for the last 15 years now.
 

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If the alt still uses the utter crap diode attachment method the earlier ones used then the alt may be bad as they tend to crack the diode leads. Then vibration makes them 'sing' to not connect sometimes in use although the alt on a tester may show it as being good all day long. The fail may not show until the alt is good and hot.

The earlier ones commonly test good yet change one and car goes back to running fine.

Someone needs to establish that the battery is not slowly leaking down while car sits too.
 

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Discussion Starter #9
I think the idea behind it is to make use of regenerative charging for the battery where possible, as an opportunity to save fuel. A novel idea in theory, but how much difference it makes (economically and environmentally) with real-world driving offset against likely more frequent battery replacements is another question though!

In reply to your second post - as far as I can tell, there's nothing wrong with the alternator itself, rather some controller seems to be detecting the battery SoC incorrectly. From what I can tell, it's doing a good job of maintaining the battery at what it considers to be 80%, it's just a shame that's 12.2v or so...

I'm just a bit lost as to what I should do about it. I've had the problem dismissed a couple of times due to battery and alternator working fine under test, and I'd rather not pay Ford their diagnostic charge to do the same (or tell me what I already know - no DTC codes present) unless I know for sure they will understand the problem.

Just to go into a bit more detail about forscan observations - I can pull up state of charge along with battery current in the software 'dashboard' and watch what happens. Resting, the battery is around say 80%, with current at a few amps from the battery (ignition on, engine off). Starting registers a few hundred amps and discharges the battery slightly - this is followed by the alternator feeding tens of amps into the battery for a while to bring it back to the 80% mark, at which point it cuts back to around zero again. This all aligns with voltage measurements I've taken at the vehicle battery.

The alternator responds correctly to changing loads e.g. heated windscreen will register initially as a large negative current from the battery, then it ramps back to around zero as the alternator adjusts. Again this agrees with voltage observations - an initial dip followed by a return to battery voltage.
 

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A battery at 12.2 volts is not at 80%, they are considered at zero % at 12.0 volts. That would be on a fairly new one, an old one it could be true on. On a new battery at 12.8 volt I would think 80% would be 12.5-.6.

At least on the earlier cars with a little less electrical load than yours the batteries give trouble at 12.2 volts, I consider 12.3 as the absolute lowest one can go before having troubles. Not all particular cars will do it right on cue but enough of them after my testing of hundreds while doing it as a job to draw a pretty good conclusion that holds up really well.

I myself am pretty quick to suspect any absolute numbers given by foreign (non-OEM) software and forscan fits that to me. While it's very useful I've found some software calculations to not be as accurate as I think they need to be. Battery volt there may be more accurate than % which cannot actually be measured per se. Charge cannot be measured on the fly 100% accurately anyway as some of it is surface and needs time to sink into the plates to get a real world battery reading.

If the system stops charging at 80% then there will be NO regenerative charging going on, the same control being exerted in any case.
 

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Discussion Starter #11
With regard to the voltage not being 80%, yeah that's exactly what I mean about something being amiss.

Forscan (or any similar software, OEM or otherwise) is only displaying a number reported by the car, it's not measuring anything itself, and it tallies with observations made with a multimeter across the battery terminal - i.e. what I explained about it stopping the charge early.

The car's BMS estimates this battery percentage (SoC) based on resting voltage combined with current measurements taken from the current sensor on the negative terminal of the battery (and maybe other sources); it knows how much current has flowed to/from the battery.

The 'smart charge' system pulls back on regular charging i.e. at idle, when cruising, etc when the battery reaches 80%, but by leaving 20% 'empty', it allows regenerative charging when engine braking for example - the alternator can put energy back into the battery that would otherwise be lost to heat in the brakes. If the battery were maintained at 100% constantly, there would be nowhere for this energy to go.
 

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The battery can overcharge a certain amount past 100% and then eat it later and what surface charge is. How you can get well over 13 volts yet come back later and it's gone. So, the last sentence there is wrong. There IS a place for it to go. To a certain point anyway.

If the battery is maintained at 100% ALREADY why do I even NEED extra regenerative input? See where I am going with that? Not saving anything, ALL alts on the planet have greater charging power (75-100 volts) than what the batteries can hold and the battery just gets it when needed.

If I am in the dead of winter and trying to start a car I want 100% in my battery NOW, not only at coasting time. Having 100% power is about having max CCA available at the time the greatest load is put on the system. 80% won't cut it there.

And pretty sure you are confusing regenerative charging with regenerative braking which is more what you are talking about, there is no 'regeneration' with an alt as alts have externally excited fields rather than permag ones. In other words an alt can not 'generate' power. Only a generator can do that. The alt can still charge at coastdown but they've done that for 65 years. The only real difference there recently is the use of decoupler pulleys to let the alt coast down at a different rate from the engine. That's more for idle quality than anything else.

Focus alts have used a version of smart charging since '00, I rebuild those. The earlier ones still charge the battery to the full 100%, I can't say about later versions but if they lower it it's likely to protect the weak -ssed alts Ford makes, they overheat at the drop of a hat. The aftermarket had to step in and redesign parts on the earlier ones because Ford refused to try to improve them. It's a Ford thing now, if a part works for a while, they do no mods to improve that like they would have back in earlier years, it's more important now to sell more parts to replace the bad ones instead. It makes the company more money.
 

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Discussion Starter #13
That's just the theory behind it - you need to have somewhere to put the energy (and quickly) if you're to make use of regenerative charging.

Charging a battery much past 'full' will result in overcharging e.g. turning the electrolyte into oxygen and hydrogen, or even heating and boiling it off in extreme cases, potentially harming it either way. There's a finite amount of energy that the battery can store, and charge state also has an effect on charge acceptance i.e. how much current the battery can usefully accept - maintaining the battery at a lower SoC like 80% means the regenerative charging system can dump more energy into the battery in short bursts when it's available - maintaining the battery at close to 100% would result in negligible recovered energy therefore rendering the system useless.

I've heard about systems which use a large capacitor for this storage rather than the battery and avoiding the potential downsides.

As for where the efficiency benefits come from, the alternator obviously puts an extra mechanical load on the engine via the accessory belt when it's outputting power (noticeable by a change in engine tone or momentary drop in idle revs when switching on large loads), which results in increased fuel consumption. In theory, if the system can recover sufficient energy from regenerative charging, it may never need to place additional load on the engine in such a way that it would increase fuel consumption.

It's first and foremost a way of improving fuel economy, at least under certain circumstances. Like auto stop-start, how much difference it makes under various driving scenarios is going to vary.

A normal alternator regulator will just hold the voltage around the float charge level of the battery, responding to changing current demands (I assume you mean amps rather than volts - voltages that high would destroy the regulator and battery, let alone the car's electronics). As charge current taken by the battery is a result of voltage applied to it, the smart charge system can constantly vary the voltage to alter the current, as far as equalling the battery's own voltage so as to power attached loads without actually passing any current into the battery.

Cars utilising this technology however do tend to use fairly large batteries anyway, so even at 80% SoC they're likely storing more energy and CCA ability than a standard battery would have done.

Anyway...

That's the theory behind how it works. I'm just wondering about why the system would wrongly measure state of charge!
 

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I meant VOLTS, you can't get amp without getting volt too. All alternators for the last 50 years have had the ability to make up to 100 volts when left unchecked by a regulator.

'In theory, if the system can recover sufficient energy from regenerative charging, it may never need to place additional load on the engine in such a way that it would increase fuel consumption.'

Not necessarily so, the charging slows the car down faster at decel, as always there is no such thing as free power. Magnets exert drag on charging rotors. Not possible anyway, you need the car more in steady state or increasing state (accel) than decel and always, the 3 states are never close to equal. The theory is perpetual power which does not exist.

And you still have missed the point that an alternator cannot generate power without power being supplied to it in a field, that's NOT a generator. Meaning there is no 're-anything'..................regenerative power is made up out of nowhere, the making device generates it with no power going in to do it. It requires big magnets which alts do not have.

FYI, a battery when supplied with diodes to retain charge IS a capacitor in its' action and behavior.

I think you are confusing new wave technology used in hybrids and electric cars with non-hybrid tech.
 

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Discussion Starter #15
I'm afraid you're the one misunderstanding a few concepts and/or my posts. An alternator being electrically able to create a voltage of 100v under fault conditions does not mean it could do anything useful with that; as I said it would most likely destroy the regulator (semiconductor devices have breakdown voltages), and even if the alternator were capable of maintaining any current at that voltage (likely not with a big lead acid battery in circuit), it would not be useful for actually charging a 12v battery as opposed to releasing a lot of gas through electrolysis and boiling of the electrolyte. But this is not something I was ever saying - there's nothing overly special about the physical alternator in this system, just the ECU has more control over the excitation current vs a normal system.

The part you quoted is exactly right if you read it properly. If the system can indeed recover sufficient energy from regenerative charging (i.e. energy which would otherwise be lost as heat in the brakes), the alternator may never need to run in such a way that it causes the engine to draw additional fuel. That's in an ideal world of course - in reality, that's likely to vary based on driving conditions. Slowing a car requires the braking system to dissipate a lot of energy - provided it can be usefully recovered through regenerative charging (batteries have their limits with regard to charge acceptance), it's not hard to see why even short bursts of slowing would be enough to power a vehicle's basic electrical systems.

At no point did I mention or even imply the notion of perpetual energy.

I'm not sure what you're getting at with regard to 'NOT a generator' - do you mean an alternator? Because an alternator is a generator. In fact that's exactly what Ford call the alternator in their service manuals. Generating electricity is not exclusive to the permanent magnet variety.

You're partly right about power needing to be supplied to the field coils (the excitation current, which is controlled by the regulator to vary the alternator's output), however the amount of power used for the excitation current is far smaller than what the alternator produces, or else what's the point in having one? In fact I'm not sure what you think the point of an automotive alternator is if it's not to generate electrical power from mechanical input?

Regenerative charging/braking is just a way of recovering energy from slowing a vehicle which would otherwise be lost to heat. It's not exclusively used in hybrid/electric vehicles and the principle is very similar in Ford's regenerative charging system - just in this case they're not putting the electrical energy back into traction motors from the battery. In fact the technology has a lot of applications including in trains - slowing high speed trains takes a lot of doing, and being able to dump some of that energy back on to the electrical grid helps to resolve some engineering challenges, and save on replacing brake pads! Even when the energy can't be recovered, some trains use dynamic (or rheostatic) braking, where they use the traction motors as generators (same as hybrid/electric cars), but dump the electricity into resistor banks with huge cooling fans blowing across them.

A battery does not need diodes to hold a charge (diodes in the form of an FBR are used at the alternator's output to rectify AC into DC) and is a very different device to a capacitor. At a very simple level they store electrical energy but do it in very different ways. An advantage to using a capacitor (usually double layer, often marketed as 'supercapacitors' in this sort of application) over a battery is due to a capacitor's greater specific power, better cycling ability, and not having to endure the negatives of holding a lead acid battery at less than a full charge.

Now we understand I'm not confusing anything, and that I'm perfectly happy with how the system works, I wonder if anyone understands the system from a diagnostics point of view as per my original posts?
 

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Hello ExSpark.

Before I comment in your thread, I need to introduce my lack of knowledge & experience with your 2013 (Euro) smart charging system.

I have no idea what is wrong, but wanted to chime-in anyway.

After reading the PDF (linked in post#2); the system seems very strange to me because of my total-lack of experience with it. I also agree with some of amc49's comments and insults about this system.

My 2004 has a smart charging system, but it is much different, and it does not have a battery monitor sensor (BMS).

...the first indication anything was wrong was Stop-Start wouldn't function...
This Stop-Start is engine ignition? -right? So your car engine was not starting? So, your car did not start until after your replaced the battery?

...I'm concerned it could be something about the smart charging system not allowing the battery to receive a full charge,...
Me too.

Something does not seem right to me. Battery voltage too low.

Take another look at that PDF, at the last paragraph... Please forgive me and the asterisks **** below. An error in my copy-paste.

"To*function*with*high*accuracy,*the*Battery*Monitor*Sensor*must*be*recalibrated*at*regular intervals. A*recalibration*occurs*during*a*rest*period*when*the*battery*quiescent*current*is*less*than 100mA. This*rest*period*must*last*for*at*least*3*hours. The*longer*the*rest*period,*the*greater*the*accuracy.
The*timeframe*in*which*a*recalibration*must*take*place*is*seven*days. If*the*system*has*been*unable*to*carry*out*a*recalibration*within*7*days,*the*SOC*accuracy cannot*be*guaranteed. This*will*result*in*the*Start*–*Stop*and*SRC*systems*being*deactivated."

Maybe your car is sometimes unable to re-calibrate the BMS? Maybe the BMS (PCM) is not performing this test due to a parasitic battery current drain just above the 100mA threshold?

Maybe the BMS is not feeling good, and it just needs a pint of beer and a warm hug? #carsneedlovetoo

Good luck.
 

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Discussion Starter #18
Thanks for the response Marde. I don't disagree with some of the opinions posted about the system e.g. about battery treatment and likely real-world benefits, but I've not done much in the way of research into how well it all works. Like I say though, it likely has a lot to do with individual driving style (e.g. neutral coasting when slowing won't help it) and whether most miles are highway or city driving. I understand the theory behind it reasonably well, and it must make enough of a difference to at least lab MPG figures to be worth implementing for Ford.

Auto stop-start is an increasingly common (at least in Europe) feature aimed at reducing fuel consumption/emissions when idling. Given some requirements are met e.g. the engine is warmed up and electrical demands are manageable, the system will automatically shut off the engine when the gearbox is in neutral and the clutch lifted (and some equivalent for auto transmissions). Pressing the clutch to engage a gear automatically restarts the engine (quickly). If a drive involves lots of waiting in traffic or at lights it can make a fair difference, but at the expense of increased wear and tear on the starter motor, though they're usually beefed up to compensate somewhat. Some systems even stop the engine at a precise point, storing a fuel-air mix ready to ignite in one cylinder, and firing the spark to aid in restarting with less starter motor wear.

Why I thought that was an indication of battery trouble, is that battery condition/SoC are common reasons for the system not activating. It's not the feature I missed in itself, rather it was indicative of something else.

I did perform a parasitic drain test and while I can't remember the exact reading, I remember it was below the threshold for BMS calibration, and the car is frequently left with plenty of time to calibrate.

Having said all that, after checking for DTCs with Forscan and allowing the system to perform some self-tests, I've been driving about as usual and voltages weirdly seem far more reasonable now; e.g. 13v ish straight after ignition-off (so clearly charging) and 12.5-12.7v resting, more where you'd expect it to be for an 80% target.

I'll keep an eye on it, but maybe some self-test or random event has reset something. I'm not going to pretend I know exactly what has changed though!
 

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Hi, haven't been here for a while but there's some very interesting insight being shared on this thread, that is so pertinent for the kind of skills required by the DIY auto mechanic nowadays. I have never diagnosed an issue like this before but I stumbled across the Helm Ford Focus 2012-13 Shop Manual in my archive and I think it might help you, especially Section 14. I've uploaded it here -

http://www.filedropper.com/helmfordfocus2012-13shopmanual

Just use something like WinRar to uncompress and open file Index.htm in the main folder.

Good luck
 

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Discussion Starter #20
Hi polygon, thanks I actually stumbled upon that manual in another thread when I was initially researching this problem. The troubleshooting sequence for the charging system didn't reveal any sequence; the alternator was functioning correctly and responding to commands, and no DTCs present.

It's why it's particularly strange - like I say the BMS was reporting the battery at 80% state of charge when it clearly wasn't. If something pulled the battery below reported 80%, it would recharge it to that 80% mark then stop. And likewise if the battery was over 80%, it would cut back on alternator current allowing the battery's charge to drop back to 80%.
 
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