I think my wife's 2012 Fabia Elegance estate 1.2TSI petrol (105PS) needs a new battery.

The alarm has been going off randomly, and it doesn't start quite as easily as it used to.

I checked the voltage and it was 11.9V, so I reckon it's on the way out.

I suppose having lasted 8 years is pretty good going.

 

Everywhere online that I try seems to think it needs an 012 battery, but they are 210mm long, whereas the original one in the car is 240mm - I think that might be an 027.

I can't see any obvious model number on the existing battery.

 

Anyone know what the correct battery is for this car?

 

Thanks.

Edited 30 October, 20205 yr by cliveb

11.9V isn't on the way out, it's completely knackered!

 

https://www.puretyre.co.uk/car-battery-specification-chart/

 

A very handy little chart, this plus a tape measure should answer your question.

41 minutes ago, sepulchrave said:

11.9V isn't on the way out, it's completely knackered!

 

https://www.puretyre.co.uk/car-battery-specification-chart/

 

A very handy little chart, this plus a tape measure should answer your question.

 

Thanks for the chart. The only battery that has the same dimensions as the existing original is 027, so weird that everyone says the car needs 012.

 

Agreed that 11.9V is very low. Amazing that the starter motor even turns over! But the car does still start fairly easily. Go figure.

It's a low compression petrol engine, you could probably hand crank it.

The problem is the voltage, not the current, the cars electronics hate low voltage, the starter motor doesn't care, the starter would still turn with 6V, it would just be very slow.

If its the same as mine, 027 is correct. This is the one I had recently. (eBay). A shade under £60.

 

1x Premium 64Ah 640CCA 12v Type 027 Car Battery 4 Year Warranty - EA640

OK, so I got a Yuasa 65Ah 027 from Tanya. (Excellent service from them, BTW).

Fitted it without any problems and assumed the problem would be sorted.

 

But no! The alarm went off on its own again yesterday.

Now wondering whether to even attempt to get the problem diagnosed. My guess is that it could take a long time and cost quite a lot of money to have it traced by a pro.

Or might it be that the car's data system keeps info about what caused the alarm to trigger that can be easily read by a dealer?

 

Given that most people ignore car alarms, perhaps it's simpler to just unset it when locking the car. But would that invalidate the insurance?

Prior to fitting the new battery, did you charge it? 

I have had numerous batteries that, despite saying they are fully charged from purchase, have been put on a charger with built in tester, only to say they are around 60% charged. They are usually dry charged from new and then, once purchased, the acid is added and to me, that seems to be why they then need additional charging as they may well have been standing around ages first, then filled with fluid that may just then dilute the charge a little. I may NOT be technically correct on my description but it seems to be the case, regarding the charge, anyway! Test the charge and if needed, top it up fully.

A note - "dry charged" means that the battery was originally filled with electrolyte (dilute sulphuric acid), fully charged, then drained. A normal, wet cell lead-acid battery cannot be charged dry. The battery is then drained to reduce the risk of spillage during transport/storage - and to reduce the rate of self-discharge while stored. It is correct that the battery should again be fully charged before being put into service.

2 hours ago, mrgf said:

Prior to fitting the new battery, did you charge it? 

I have had numerous batteries that, despite saying they are fully charged from purchase, have been put on a charger with built in tester, only to say they are around 60% charged. They are usually dry charged from new and then, once purchased, the acid is added and to me, that seems to be why they then need additional charging as they may well have been standing around ages first, then filled with fluid that may just then dilute the charge a little. I may NOT be technically correct on my description but it seems to be the case, regarding the charge, anyway! Test the charge and if needed, top it up fully.

 

Its been at least 15 years, maybe 20 since I have bought a new battery where the cells could be refilled, they have all had the top part of the case with the breather galleries bonded on during manufacture.

 

If only I were able to top up batteries during service, I have wrecked a few casings trying to do so.

 

No argument against checking the state of charge before fitting to the vehicle & charging before cranking if it is low.

Modern sealed Lead acid batteries are filled and sealed at manufacture, they use calcium to prolong shelf life and reduce self-discharge. As soon as such a battery is filled it is immediately available for use and requires no charging beforehand, it is conceivable that a battery that has sat on the shelf for a long time would need a top-up charge but it's very unlikely.

There is no accurate way to determine charge capacity of a lead acid battery but if it's new then it'll be VERY close to 100%.

Close enough to fit and forget about.

23 hours ago, cliveb said:

OK, so I got a Yuasa 65Ah 027 from Tanya. (Excellent service from them, BTW).

Fitted it without any problems and assumed the problem would be sorted.

 

But no! The alarm went off on its own again yesterday.

Now wondering whether to even attempt to get the problem diagnosed. My guess is that it could take a long time and cost quite a lot of money to have it traced by a pro.

Or might it be that the car's data system keeps info about what caused the alarm to trigger that can be easily read by a dealer?

 

Given that most people ignore car alarms, perhaps it's simpler to just unset it when locking the car. But would that invalidate the insurance?

Get it scanned with VCDS or similar. My bet would be cracked wiring between the driver's door and body, or a flaky switch inside the lock, either of which could intermittently make the alarm think the door has been unlocked and decide to go off. The door control module will have stored codes related to this if it happens to be the problem.

JR and Sepulchrave, I agree with the sealed part, my comment was old tech for batteries but still later then the old "Top up with distilled water" Type ones. They still used to get filled and sealed at least for some time after this. But regarding the charge state, if there is no accurate way to determine the charge capacity, how can you know if its close to 100%? Thats a contradiction in terms, surely? I realise that a worn battery will still tell you it is fully charged and at 100%,, once you charge it, despite its capacity being way down on the capacity it would have started from when new but as I have mentioned, I have had a few batteries that have been "Brand new" which still stated on a reliable charger, to be around 60% and which took a decent charge until full. I have also had new batteries I have accepted as being fully charged and they have been the ones I have had to replace quicker so I am happy in my calculation that charging prior to fitting, is still much better. If you have had a duff battery, waited a few days say, for a replacement, etc, why not just go through the motion of charging fully anyway? There is absolutely nothing to be lost. I know any battery only has a finite amount of charges that can be put in to it but that one, along with a certain amount of "Top-up" Charges you may give the battery during its life, will not impact on that and MAY actually improve on it as when driving, you will most likely take out more power then you put back in, if you drive very short distances, low revs, heater and lights etc all on. It used to be said that it takes around 15 mins of continued driving, to put back in the charge used, starting the car initially.

As others have said, a car alternator (or generator/dynamo) won't easily charge any battery to completely full.

That's because they are "one step" chargers and use a compromise voltage.

To fully charge a lead acid battery you really need at least three steps. First a rising voltage that keeps the charging amps constant whilst the battery voltage improves. Once the charging voltage reaches about 14.4v, the charger should switch to constant voltage mode, stay g at 14.4v whilst the amps gradually diminish as the battery voltage continues to improve up to its "surface charge" voltage of about 13.3v. That gets you a 100% charge, and the charger then switches to a maintenance voltage of about 13.5v (just higher than the surface charge voltage) to maintain the battery in a fully charged state.

Your alternator uses a maximum voltage of about 14–14.2v. This gets a good but not full charge into the battery (that needs 14.4v or thereabouts), but Since the alternator STAYS at that 14.2v or so rather than dropping to 13.5, it can end up overcharging after a long drive, but only a little at that 14.2v setting and lead acid batteries are usually quite good at accepting a slight overcharge.

So putting a brand new car battery on a multi step smart bench charger overnight is a good idea just to get the battery right up to specs.

In fact I do this with all car batteries once a month or so, just to make sure the battery does see a 100% charge every now and then. My batteries last a long time.

Stop/start driving is hard on batteries too - that slightly low alternator voltage won't charge it full and every start drains the battery a bit, and together with the heavy electrical load of modern cars, it is possible to have the battery continually at part-charge, which results in a shorter life. An occasional charge from a bench charger is good for battery life.

 

 

Rob Boardman

, former ATC, truck Driver and Reader of Everything

Go here:

 

https://batteryuniversity.com/

 

Rather than performing obscure rituals you can learn about the actual chemistry very quickly and easily.

 

If you pour fresh dilute sulphuric acid into a brand new but dry lead acid battery you will have 100% of the battery capacity available for use right away. I already told you this.