Hi folks,

My 1.6diesel greenline would not start the other day, after sitting for 72hours the battery (less than 12months old) was at a meagre 3.5volts!

Parasitic draw was the RAC suggested culprit, my tests however show a normal draw of 0.03A

Has anybody any ideas what could have caused such a dramatic battery depletion?

Thanks in advance

Matty

Well of course it could be a Battery problem.

Fully charge it & check voltage. Let in stand overnight. Then check voltage again.

Let us know the readings.

Edited 2 June, 20251 yr by Carlodiesel

I put a new battery on Saturday morning. Last night it was 12.6, this morning it was still 12.6…. I’ve not used it all day and it’s still 12.6.

The old battery shouldn’t have dropped to 3.5v so quickly, the battery was only 12months old

Age has nothing to do with it.

Only last week I got a new battery for a M/c & it was 11v delivered.

Next day it was 10v. Not used.

I fully charged it. Let it stand overnight & it was 10v again.

Got it replaced foc.

Dig out your receipt & give them a call.

My January 2015 Greenline battery must be on borrowed time but still starting like new.

I got the new battery for free as a replacement, but it was suggested that a drop as low as 3.5volts would be indicative of damage to the battery by overcharging or overdraining and that the warranty should not technically apply.

2 hours ago, Urrell said:

My January 2015 Greenline battery must be on borrowed time but still starting like new.

That's pretty good. Had to replace our Subaru's after 12.5 years in April after it started behaving strangely but still started first time. I trickle charged it every month with a CTek but it was finally terminal all of a sudden - wouldn't start or charge and the idle was bouncing to 3000rpm on its last trip. Both the Subaru and Yeti (8 years old) have had a new Varta from Tayna now !

i buy new battery every 5 years or less, nevermind of battery state..

2 hours ago, imart143 said:

i buy new battery every 5 years or less, nevermind of battery state..

You are free to do as you please but that is probably very wasteful, car batteries must remain one of if not the most oversold car parts, replaced prematurely out of choice in your case or through over-use, abuse and neglect and lack of knowledge, that more drivers had more of with previous generations of cars and people.

Edited 4 June, 20251 yr by nta16
typos

If I get a new battery I always check if it is fully charged (to 100%) and if not fully charge it to 100% with an appropriate battery charger (at low amps 4-amps for modern medium/larger before fitting to the car.

An AGM can arrive with 12.4v charge (full might be 12.8v or 12.9v) and be ok to be fitted to a modern stop/start car but I still fully charge it to 100% just so I know exactly how the battery is when I fit it as a new battery.

Very rare to have a duff battery (unless perhaps you're a car manufacturer like say VW or Nissan then you blame the battery manufacturers to cover yer arse, perhaps, maybe, allegedly, surely not VW, no).

If you buy a cheap battery and/or from a cheap or poor quality supplier then it may be out of date old and/or stored and kept incorrectly.

@Mattylomas1 for your previous 12 month old battery to drop to 3.5v sitting in the car for 72 hours seems very strange - if required are you sure the previous battery was 'coded in' correctly, on here a chap had a professional auto-electrician key in 7ah instead of 70Ah and it done for his battery after x-months (I forget x). I've seen 2.5V on a neighbour's Beemer that had been sitting for months and less than 1v on a Jag XJ that had been driven that day (coldest of the year) and had the heated seats on and other stuff showing the car off (at 5am!) to Jag owner's boss despite knowing the battery was low for a number of weeks (some people don't help themselves). I had to check my multimeter as I thought the cold was affecting its electronics.

A 2025 VW I'd only hope to see 8-10 years out of the battery but a 2012 I'd expect longer but different people use different amounts of electricity and different use of the car, plus a 13 year old car isn't new of course but used and worn to varying degree.

i buy a new one and after 5 years its near eol, because of many cold starts and stop go driving. i am buying oftenly Exide, and when i think its done i give it for gift to someone who have no money for new EFB+ battery.

i charge battery on external charger every 6 months.

i dont buy VAG batteries. too expensive.

exide efb for my car is 130€ in my country.. AGM is 160€. takling about 60 Ah

maybe i put AGM next time. what do you think. ofc decoding in odbeleven.

or this, 62 Ah thats with new stickers

Edited 4 June, 20251 yr by imart143

We see very few EFB + battery here I have no idea if VW even have a coding for such, OBDeleven might but that is not the same thing.

I find it best to charge to the battery to full 100% charge (if the battery will take it) not the VW 70, 75, 80%, using an appropriate battery charger maintainer following the instructions of the charger and those in the 'Owner's Manual' for the car, using a charger of lower amps, currently I use a 4-amp charger on my wife's 2015 Fabia. It can take many hours to top that up. You charging every 6 months to however you do it might be enough and ideal only taking readings would really tell but it is much more than most do and you get your batteries to 5 years still with more useable service life in them and as you are passing them on they are not wasted.

At the moment in my shed I have a neighbour's car battery and I am using my 30+ year old semi-"smart" 1.9 amp charger maintainer, I expect it to take a minimum of 24+ hours to fully recharge to 100%, if it can, judged on first connecting it up to my 40+ year old (not "smart") battery charger with a useful swing needle display on it to see how much the needle moves in 5-10 minutes based on decades of experience doing the same for other neighbours.

Photo from internet.

Batteries like about 20C weather temperatures, IIRC(?) at 30C they self-discharge at double the rate and double again at 40C.

AGM batteries are supposed to have more insulation around them if fitted in the engine bay (the one I fitted to my wife's car doesn't even have the full insulation for the factory battery as the car came with the lid part missing, I have just risked it as it is, I have a low hassle tolerance with German marque cars as generally I don't like them.

As a general rule the bigger the physical size battery the power it holds and often cars have smaller batteries than the space available can allow for, but not always. Do not get too attached to mere numbers as it is also about performance of those number and longevity of that performance also there are many standards for the CCA (cold cranking amps) specification, see below for pdf on 4 of them.

Bear in mind I am NOT an expert in car batteries, or anything else. I have the VW Self-Study pdf on VW stop/start and batteries if you want them or they are available on the internet along with lots of information about batteries, though some battery manufacturers seem to be shy with information thy put on their websites and some information that was previous there is no longer there.

HTH.

CCAspecs.pdf

CarBatteryInformation.pdf

tnx for details, in vag services they use vag batteries according to part number and serial number or code is written in ecu, and that is enough.

i buyed 5 yo car with original battery and start stop not worked at all, it was half mpty, i charge it and start stop worked few days, than not again.

so i decided to buy a new on in battery store, change values to new battery, same type but 60Ah, original was 59Ah, CCa was same. original battery was Varta-VAG.

Some at least VWŠkoda owners, including me, have found that the VWŠkoda factory couldn't be bothered to enter the serial number and just put ten ones (1111111111). The battery information to some extent was only for VW statistics and in my biased opinion (I don't like VWs) was used to blame the battery manufacturer for VW ****-ups to do with battery/charging computer system/programming.

VW being German of course also had to use different terminology being "Simply Clever" (not) they call AGM "fleece".

So when 'coding' a new battery the important entries are to change the "serial" number so the system knows the battery is new/different, the type needs to be correct EFB/AGM and the Ah rating needs to be at least near enough correct (not miles out as one professional auto-electrician is said to have done and put 7Ah instead of 70Ah, why VW's computer programming allows this is a different matter, very poor programming in my opinion). The make of the battery is of no importance and can be left or changed at will, I didn't even stick to a three letter code.

As an example I put up what was done for me by another Briskoda member using OBDeleven. -

Edited 5 June, 20251 yr by nta16