Ok

There's probably been quite a few posts about the batteries on the mk3 fabia forum but for some reason every time I try searching it brings up results for the whole of briskoda. 

 

Problem is as follows. 

 

I have been getting start stop errors for the last couple of months with and without the emc error light on the dashboard. 

 

Most recent it was saying that the voltage was low disabling the start stop system. 

 

Just got hold of a cigarette lighter charger that shows the battery level and as can be seen in the attached photos which were taken after the engine was started, when I arrived at work and turned the engine off and before the car was started 8.5hours after leaving work. 

 

Unfortunately where I live I have no way of getting a charger connected to the battery on the car and no safe location to put the battery on charge in the house. 

 

Driving to and from work is a 10 mile round trip all at motorway speeds and I might get to do a 100 mile round trip on a weekend with the car sitting in between each journey for several hours. 

 

Any suggestions about how I sort this one out?

 

The first thing I would do is fit a new battery and bench test the old battery to see if it's worth keeping and using as a stand-by spare batttery by fully charging it and seeing how long it takes the voltage to drop to various voltage points, such as 12.8V, 12.7V,. etc.

 

My current new Varta SLA (Sealed Lead Acid) battery takes almost one week to drop to 12.8V after being fully charged, and almost eight weeks to drop to 12.7V. By fully charging the battery once it had dropped to 12.7V I was able to calculate that in those 8 weeks the battery had lost just over 10% of its capacity, ie. this is the amount of self-discharge...and is surprisingly low as I had expected a much higher rate of self-discharge from a SLA battery.

 

As it's a stop-start car I would use the superior AGM battery rather than the cheaper, lower quality EFB battery that I've heard Skoda fit to new stop-start cars in the factory. Bear in mind, that most people probably don't fully charge their 12V car batteries because to fully charge them you need a trickle charger (perhaps only 0.2A) that only cuts out when the charging voltage gets to about 14.95V...which can take many days to do. It's OK to have a car battery charger that initially charges at a higher rate such as 3.5A, but then switches over to the trickle charge rate when the charging voltage gets to a certain point.

 

Edited 2 September, 20241 yr by Carlston

Just as an additional note. 

Car is a 21 plate 1ltr auto estate. 

Charge voltage with engine running 14.6v

Battery voltage after 5 mile drive 12.4v

Battery voltage after sitting for 8.5 hours 11.9v

3 hours ago, mikec said:

Just as an additional note. 

Car is a 21 plate 1ltr auto estate. 

Charge voltage with engine running 14.6v

Battery voltage after 5 mile drive 12.4v

Battery voltage after sitting for 8.5 hours 11.9v

 

After 8 hours of sitting my car battery reads about 12.3V measured at the cigarette lighter socket with the ignition turned on but the engine not running (and not having been run for eight hours). In the winter when the temperature is very low this measurement can drop to about 12.1V.

 

Below 12.0V sounds slightly low and I suspect the battery is in need of replacement.

 

From reading other posts, I suspect it might be common for factory fit EFB batteries to need replacing after about 4 years, ie. they don't have a long life. If Skoda had fitted an AGM battery in the factory I expect this would have been a lot longer.

 

I've just measured the voltage of my AGM battery (with an accurate multimeter) at the cigarette lighter socket with the ignition on. The car has been sitting for over 8 hours and with the interior light off the voltage is 12.44V and with the interior light on the voltage is 12.41V. When the interior light is turned off again, the voltage quickly returns to 12.44V. The temperature is about 20 degrees Centigrade, so the battery voltage is slightly higher than it would be if I had measured it in the winter at about 0 degrees Centigrade. This shows that your battery at 11.9V is highly suspect because this kind of voltage shows an almost flat battery or one that needs replacing urgently. The difference between an 11.9V battery and a 12.4V battery is night and day, ie. one has very little power left and one has loads of power left. To demonstrate how even a small load on the battery causes the voltage to drop, I disconnected the battery, ie. removed the negative terminal. The voltage immediately increased to 12.64V and continued to quickly rise, soon reaching 12.69V, ie. almost 12.7V. This means that the measured Voltage is almost 0.3V higher with the battery disconnected compared to the battery connected with the ignition on and the interior light on. A 12.7V battery when measured with it disconnected, ie. no load on the battery, is probably about 90% fully charged. A car's electrical system probably never fully charges a car battery because to do that requires a very small trickle charge, perhaps around 0.2A. If a car's electrical system tried to fully charge a battery, ie. to 100% of its capacity, it would probably damage one or more of its six cells.

 

Edited 2 September, 20241 yr by Carlston

If you really feel you have no safe place to charge the battery (this isn't a lithium battery) in your house then the best thing for you is to replace the battery with a good quality new battery.  It is also best to 'code' the new battery and will certainly be required if changing from EFB to AGM battery.

 

You might have some drain on the battery from some item drawing power whilst the car is parked up, above and beyond the unusual factory stuff, do you have any items added to the car not from factory, a dash and/or rear camera, etc.?

 

14 hours ago, mikec said:

 

I have been getting start stop errors for the last couple of months with and without the emc error light on the dashboard. 

Most recent it was saying that the voltage was low disabling the start stop system. 

14 hours ago, mikec said:

Driving to and from work is a 10 mile round trip all at motorway speeds and I might get to do a 100 mile round trip on a weekend with the car sitting in between each journey for several hours. 

For months you have been getting a message that tells you the battery is low enough for the computer to disable the start/stop so your driving is insufficient to charge the battery enough to resolve this, once the battery is low and recharged enough the battery is worn more and more, a downward spiral which gets harder and harder to reasonably recover the battery from.

 

14 hours ago, mikec said:

There's probably been quite a few posts about the batteries on the mk3 fabia forum but for some reason every time I try searching it brings up results for the whole of briskoda. 

There certainly have, I have put many here and elsewhere on Briskoda.  I can post loads of info for you or you can search on here by using the 'Search' box at the top right of the page and using the drown down arrow in it to click on 'This Forum' for Mk3 Fabias.

 

If your car is under warranty have you checked with the Dealership, also for any (admitted) VWŠkoda recalls (there was one for earlier cars relating to battery issue CU97).

 

As a 2021 car is there any chance it might go back to covid production building times, have you had any other electrical issues?

 

I don't know Bletchley now (I used to live in Wolvertun, Brad'l, New Brad'l (Bradville) but that was many decades back) but wonder if you could if required on a new battery use a solar charger at home, or work,

 

There are lots of variables and bear in mind your plug-in digital meter reading is with you sitting in the car not when parked and locked up with whatever electrics are drawing power at either times.  The following VW figures would refer to the battery out of the car sitting on a bench. -

 

Charge level             No-load          voltage

1.28 g/cm3                 100%              12.7 V

1.21 g/cm3                 60%                12.3 V

1.18 g/cm3                 40%                12.1 V

1.10 g/cm3                 0%                  11.7 V

 

Ring charger figures -

 

12.7v - 100%             12.5v - 90%               12.4v - 80%               12.3V - 70%

12.2v - 60%               12.1v - 50%               11.9v - 40%               11.8v - 30%

11.6v - 20%               11.3v - 10%

 

HTH.

 

Edited 3 September, 20241 yr by nta16

I do have a nextbase 422gw dashcam hard wired in the car (can't remember which fuse it was piggy backed to) will have to check if it was permanent live or ignition live. 

 

After a 5 mile drive from home to work the charge on the battery had gone from 11.4v to 12.4v so hopefully it'll be a simple case of moving the dashcam power feed to a fuse that is definitely ignition only once one has been found with a multimeter 

You still want to fully or as very much possible ("fully") charge the battery to get the best out of it.

 

If you can borrow a multimeter I think it's best to check the battery at the the battery terminal posts as many hours as possible after driving the car or charging the battery with the bonnet up and car locked(?) (I think that's possible I forget) and car left for about half a hour for the computers and other stuff to settle, might be more on a 2021 car I don't know.  Then allow say 0.2v or 0.3v for parked up use.  This gives an idea of the battery, then if it can be repeated many hours later without the car being used it will give an idea of any drop in the battery.

 

Best not to let the battery so low that the start/stop doesn't work other than in circumstances as explained in the Owner's Manual.

 

Good luck.

Seeing as you have a DVM plugged in at all times, the clues to having a healthy battery is that when you are driving "under power" as opposed to "on the over run", that DVM should be reading 12.6/7/8 and a bit less at idle when stopped at lights.

 

The battery in my wife's 2015 VW Polo is an EFB and it sometimes does not end up well enough charged at the end of a run to enable auto stop/start - but I have worked out that that is only down to the way that "journey has gone" as I find that I can frequently end up with the car harvesting the charge from the battery - to save wasting energy. Driving in an "energetic/aggressive" manner will usually mean avoiding that happening - but give you worse MPG figures!

9 hours ago, rum4mo said:

DVM

That confused me.  😁  When I read it I thought you meant the camera, digital video monitoring?, Google gave me Doctor of Veterinary Medicine for DVM search, then I clicked on DVM electronics images of Fluke handheld meters and finally it clicked, photos at top of thread. 😆

 

I'm not so keen on those, a permanent display tends to get ignored and sometimes difficult to see in daylight (like "smart" phone  and other portable device screens), garish bright colours, gives something else to distract from driving and worry about.  VW should provide this information on the dash something you can scroll the thumbwheel to see like oil temperature.

 

A mate has a permanently installed DVM into the dash, can't see it in sunlight, didn't stop him leaving the heated windscreen on and draining the battery at the start of his journey in France.  😄  He wired it so that the tell-tale light operated instead when he put his lights on!  And he's altering the wiring on his mate's kitcar so that it has a fusebox(!), I asked if he thought that was wise, I dread to think how it'll be as his car has a spiders web of wiring from the add-ins on it.  I did mention how well fibreglass burns.

 

Hello there,

 

If you unplug the Battery Control Module from the POSITIVE terminal on the battery, This will disable the start-stop system and will allow the alternator to charge the battery to capacity.

 

If you are not aware, and AFAIK, the alternator will ONLY charge the battery when braking on overrun (Car in gear, off the accelerator, braking). "Regenerative Braking". 

 

 

Cant find a photo for the fabia, but it looks very similar to this.

 

Bare in mind it will throw up an error for the start/stop system.

 

Hopefully doing this every so often will help charge your battery

18 minutes ago, lewiswal47 said:

 

 

If you are not aware, and AFAIK, the alternator will ONLY charge the battery when braking on overrun (Car in gear, off the accelerator, braking). "Regenerative Braking". 

 

 

 

Where did you get this information? "Regenerative Braking" is a feature on Electric cars. I have never heard of such a thing on a ICE car. 

 

25 minutes ago, Norton Ian said:

 

Where did you get this information? "Regenerative Braking" is a feature on Electric cars. I have never heard of such a thing on a ICE car. 

 

Hi.

 

I understand "Regenerative Braking" typically refers to switching the polarity on electric motors to recuperate energy. 

 

The fabia is a micro-hybrid vehicle with this technology. You can read more here; https://www.yuasa.co.uk/info/technical/micro-hybrid-hybrid-vehicles-explained/

 

The fabia falls under this category;

Charge Management & Regenerative Braking (Micro hybrid 2)

A typo, negative side of battery.

 

For the rest this is from VW in 2009. - SSP-426-Start-stop-system-2009.pdf

 

More like very inaccurate info, the alternator will always charge the battery in normal driving but only up to a certain level of SOC, leaving enough "space" for it does when it is making use of what would otherwise be wasted energy that the system does during the over run and/or braking phase to "cram" as must extra charge as will be accepted by the battery, that is known as regenerative braking on these cars.

2 hours ago, nta16 said:

A typo, negative side of battery.

 

For the rest this is from VW in 2009. - SSP-426-Start-stop-system-2009.pdf

 

You’re correct yes, Negative indeed.

 

Mixing up my lefts and rights 😂

30 minutes ago, rum4mo said:

More like very inaccurate info, the alternator will always charge the battery in normal driving but only up to a certain level of SOC, leaving enough "space" for it does when it is making use of what would otherwise be wasted energy that the system does during the over run and/or braking phase to "cram" as must extra charge as will be accepted by the battery, that is known as regenerative braking on these cars.

 

Interesting, You learn something new every day.

 

I questioned my skoda dealership on the system whilst I was there and I was told essentially the car only maintains the basic charge needed (around 60% they said) and it only gets a good charging on good runs with overrun.

 

Looking on my OBDeleven also shows my battery to be at 62% capacity at present.

 

Hence why I have always opted for the occasional run with the module disconnected for some charge

9 hours ago, lewiswal47 said:

Mixing up my lefts and rights 😂

I reverse things all the time, often thinking I mean the opposite and forgetting which opposites are actually correct.

 

 

8 hours ago, lewiswal47 said:

(around 60% they said)

That's the lowest figure I've seen being quoted for this mostly I've seen 80% and recently 70%, as AGM batteries are said to be happy at 80% I'd have thought that'd be the figure but I forget things and who knows what figures VW set in their computer programs.

 

I've no idea how accurate OBDEleven or other meters are and whether it's referring to state of charge or health but just having it plugged in will pull some little voltage in its use.  For voltage see the VW and Ring figures and allow for any car electrics running and the OBDEleven but I'd have thought the OBDEleven would just show a voltage figure rather than percentage, if the 62% is state of health then the figure is more useful as a comparison against later figures and again how accurate is the figure and would it vary with another meter being used.

 

 

9 hours ago, lewiswal47 said:

Hence why I have always opted for the occasional run with the module disconnected for some charge

Some posters have put they disconnect for very long periods and others have put not to as it messes with VW's computer programming and system running, I've not seen anyone putting the world has ended either way.  I just leave it connected (generally switch off the start/stop each trip or engine start) and just do a few very occasional battery recharges using an appropriate battery charger maintainer having read the instructions in the car's Owner's Manual and charger.  This is because my wife's car regularly does very short journeys.

 

It's not just journey length it's how much of the various car's electrics is used before the start, during and after the journey.  As well as driving differently some people use a lot more than others.  I think a coin-slot meter for battery use would be useful to teach some what uses how much, particularly for young pampered offspring.

 

Attached will give you more info. - SSP-504_Vehicle_Batteries.pdf

 

One thing that I'm confidant that the car will do, is to correctly take care of any demand that you place on the alternator, in terms of when you switch on heated windows and lights etc.

6 hours ago, nta16 said:

I've no idea how accurate OBDEleven or other meters are and whether it's referring to state of charge or health

 

OBDEleven just reads the cars own sensors so its accurate to the start/stop systems information.

 

I took note of my "Battery Charge Condition" rating before and after a 50 minute (mainly motorway) and it changed from 62% to 63%. Not a great improvement. No air con, window heaters, no high demand really.

 

Also interesting that the alternator sits at a constant 14.6V whilst the battery only sits at 14.3. 

 

There are however plenty of options for live data which im going to trial in order to fully understand when and how the system charges the battery

"Battery Charge Condition" I'm not sure what this means, is it a human language translation from another language to English.  Others I've seen show battery charge in volts and battery "health" in percentage.

 

1 hour ago, lewiswal47 said:

Also interesting that the alternator sits at a constant 14.6V whilst the battery only sits at 14.3. 

 

There are however plenty of options for live data which im going to trial in order to fully understand when and how the system charges the battery

I'll leave this to @rum4mo as I think he has graphs of such(?).  Some of those selections would be interesting to see to compare with static tests with a multimeter.

 

Do have a read of those pdfs I put up, and they're from VW.