It will be interesting to see how long my 53AH, EFB, +7 year old battery lasts, battery SOC always between 72% to 83% ish vis all my other 100% charged ones, (at a constant 14.2/14.4V), where I never had a failure and used to renew them purely precautionary after 9/11 years before passing the cars down the line.

John as I've said before don't put all your eggs in the basket of scanner, or battery testers, and simple maths (not that I can do even very simple maths now). It's a bit like someone who makes a cake and accurately measures all the ingredients out exact yet their cake isn't as good as someone who goes by their experience for the amount of ingredients they use rather than accurately or even measuring.

You have enough experience to know what and when the battery might need, perhaps a quick check with multimeter probes on the battery terminals.

I'm very much with Warrior193's idea that leaving the battery charging all to the car's charging system, rather than using an appropriate charger maintainer to get to 100%, shortens the useful service life of the battery.

Whilst I don't like to change a battery prematurely it's always best to change it before it really "dies" on you and can't be recovered.

I changed the EFB battery on my wife's 2015 Fabia prematurely just to eliminate any possibility of her having any hassle from it as that would have meant me having to get involved with the car (yeah, that didn't last).

Edited 30 March30 Mar by nta16
typos

It's been niggling at me why my battery suddenly gave up the ghost Sunday morning. I tried the thing of starting the car this morning (started just like it usually does) with 14.0 volts showing on my little meter, then turned on the headlights, the heated rear window, the heated windscreen and the fan up on high. The voltage dropped to about 13.5 volts and then went up a couple of points. I've been out in the car, my usual two 5 mile runs, and its started without problems each time.

So what could have caused the problem? Once in a while I'll forget to unplug the sat-nav but didn't seem likely. Then I thought about my regular journey - to walk the dog in the local woods. Usually it is a reliable 5 miles journey each way but over the last couple of months the local authority has spent a small fortune reducing carriageway widths, tightening corners and widening footways on an important local staggered cross roads to create a wonderful cycle route where you seldom see a cyclist and this has meant traffic signal on all arms with long delays. It usually has been taking two and sometimes three complete cycles to get through the junction. With very long inter-green times I have been switching off my engine whilst waiting, moving forward and then switching off again. I'm now thinking with a four and a bit year old battery these repeated starts a couple of times a day over weeks may have drained the battery more than the driving sections were able to replace. Basically I've been using stop/start without the technology and bigger battery that this needs.

Electrical engineering was my nightmare when I trained to be a civil engineer (best advice from the relevant professor was "You will be young civil engineers. When you go out on site and there is an electrical problem CALL A <expletive> ELECTRICIAN it will save your employer having to scrape you off the wall, what's left of you". I digress) so I don't know whether that's right or if I'm even on the right track but I think we can say I won't be switching the engine off at those road works again. Lesson learnt.

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth"

~ Sherlock Holmes/ Sir Arthur Conan Doyle

Try a DIY load test, first ensure battery is showing a reasonably high SOC, with the multimeter probes on the battery terminals get someone to crank the engine on the starter and note what the voltage drops to.

On 29/03/2026 at 11:57, Paul52 said:

Morning all. Went to start the car this morning and lots of dash lights came on and a horrible noise from under the bonnet, as you can hear in the video. After three or four attempts at starting everything is dead, no warning lights, no sidelights and I'm not going to risk locking and unlocking as the tailgate has locked itself. As you can see in the video I tried connecting a jumper "battery" but now find that this one from Lidl doesn't hold it's charge as well as my father-in-law's Noco one, so it's now on charge - pay cheap pay twice?). A cheapo battery meter is now showing just over 7 volts. The battery is a Bosch fitted in September 2022 with a four year warranty (so just six months out of warranty). There's been almost no warning although I mentioned to my wife the last couple of mornings that it seemed a bit sluggish starting but was fine for the rest of the day. It gets at least two 5 mile runs every day.

I'm hoping it's just the battery given up rather early (I'd rather buy a new one than take a chance on getting this one back functional - at least this time it's let me down in my own drive) but decided it's worth asking for any thoughts here before I rush into anything, not least whether the battery failing like this could be a symptom of other problems. It's as well to be prepared for the worst.

(This could be the day I regret not buying a battery charger "just in case").

A four year warranty starting in Sept 2022 will run out in Sept this year.

Sorry typo - September 2021. Fat fingers, bad eyesight and declining mental abilities not ideal for existing in the modern world. But not a bad description of a lot of us Yeti owners 🙂. (See, it's only us old 'uns that think the original smiley face is still cool. Or use the word cool).

2 hours ago, Paul52 said:

It's been niggling at me why my battery suddenly gave up the ghost Sunday morning. I tried the thing of starting the car this morning (started just like it usually does) with 14.0 volts showing on my little meter, then turned on the headlights, the heated rear window, the heated windscreen and the fan up on high. The voltage dropped to about 13.5 volts and then went up a couple of points. I've been out in the car, my usual two 5 mile runs, and its started without problems each time.

So what could have caused the problem? Once in a while I'll forget to unplug the sat-nav but didn't seem likely. Then I thought about my regular journey - to walk the dog in the local woods. Usually it is a reliable 5 miles journey each way but over the last couple of months the local authority has spent a small fortune reducing carriageway widths, tightening corners and widening footways on an important local staggered cross roads to create a wonderful cycle route where you seldom see a cyclist and this has meant traffic signal on all arms with long delays. It usually has been taking two and sometimes three complete cycles to get through the junction. With very long inter-green times I have been switching off my engine whilst waiting, moving forward and then switching off again. I'm now thinking with a four and a bit year old battery these repeated starts a couple of times a day over weeks may have drained the battery more than the driving sections were able to replace. Basically I've been using stop/start without the technology and bigger battery that this needs.

Electrical engineering was my nightmare when I trained to be a civil engineer (best advice from the relevant professor was "You will be young civil engineers. When you go out on site and there is an electrical problem CALL A <expletive> ELECTRICIAN it will save your employer having to scrape you off the wall, what's left of you". I digress) so I don't know whether that's right or if I'm even on the right track but I think we can say I won't be switching the engine off at those road works again. Lesson learnt.

Whatever about the effect on battery longevity high power loads like say 300A cranking on starting, has, the energy demand is very low per start, a 3 sec crank at 300A only requires 0.25AH, even multiple starts on short runs should easily be made up, IMO, by the Alternator.

I have noticed with my car it charges circa 14.5v on idle, but on higher revs drops to 12.8 ? is this a function of "smart charging"

You all lost me when you started talking about

.

.

.

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gambling and loose women.

9 minutes ago, Crucian said:

I have noticed with my car it charges circa 14.5v on idle, but on higher revs drops to 12.8 ? is this a function of "smart charging"

Yes, mine always charges at 14.5 or even higher on overrun, it will/can then drop to 13.5ish but I've never seen as low as 12.8V on the DVM, I've noticed of late though that if the ambient falls to say 5.5/5.0C, that it will charge continuously at ~ 14.5V but once the ambient rises to 6C, will return to its normal charging pattern.

Paul you're over thinking it and possibly over complicating it (which would make you more employable with German car marques).

Paul with your 14v and engine running you're really more measuring the alternator rather than the battery.

Whilst the battery and alternator work as a pair, if one's weak it puts more strain on the other, as shown by the figures from others the computer system for charging and battery monitoring which will throw up various figures in various circumstances.

As has been put a few engine starts does very little to a battery if it and the charging system are in reasonably condition and in fact as I've put the battery has to be very low indeed to have any difficulty starting the engine and you will hear this difficulty in starting.

First thing to do is, as your preference, to fully and properly recharge your existing battery or buy and fit a new battery (and have it 'coded' in) and then go from there, have a solid foundation and start datum point.

I would always fully charge the new battery to 100% before fitting it to the car - to give best solid foundation and start datum point.

If I had your car and battery I would start by fully and properly recharging your existing battery, in the manner mentioned before in this thread, and go from there - you may want to chose differently, your car, your money, time and hassle (very easy clean hands work).

Edited 31 March31 Mar by nta16
typos

You're good with "Paul you're over thinking it". You've never met me and yet diagnosed my tendency to jump to the worst case scenario and work backwards 🙂. You also get a thumbs up from my wife, who has never believed in loyalty.

I've bought the Ring battery charger and it's on the car now doing its thing (or so I assume - the instructions are in those pictograms that are universally incomprehensible). Since the weekend (and I know it's only Wednesday today) the car has been starting as normal and it's had two decent runs of 40 miles or so the last two days to the vet - for those who think £100 for a battery is a lot of money, my advice is don't get a Cocker Spaniel no matter how cute they look. So I'm going to do my usual thing of crossing fingers, stick my head in the sand and hope it was "just one of those things". It is due to go in for MOT and service in the next few weeks so if nothing else goes wrong between now and then I'll get them to test the battery and charging whilst it is with them - they're a local firm that I've been going to for 10 years or so and I can trust them to be honest.

3 hours ago, Paul52 said:

You're good with "Paul you're over thinking it". You've never met me and yet diagnosed my tendency to jump to the worst case scenario and work backwards 🙂. You also get a thumbs up from my wife, who has never believed in loyalty.

I've bought the Ring battery charger and it's on the car now doing its thing (or so I assume - the instructions are in those pictograms that are universally incomprehensible). Since the weekend (and I know it's only Wednesday today) the car has been starting as normal and it's had two decent runs of 40 miles or so the last two days to the vet - for those who think £100 for a battery is a lot of money, my advice is don't get a Cocker Spaniel no matter how cute they look. So I'm going to do my usual thing of crossing fingers, stick my head in the sand and hope it was "just one of those things". It is due to go in for MOT and service in the next few weeks so if nothing else goes wrong between now and then I'll get them to test the battery and charging whilst it is with them - they're a local firm that I've been going to for 10 years or so and I can trust them to be honest.

😂 Dont worry about it, I think I'm the same. Its hard not to think about it and just see what can be found instead.

18 hours ago, Paul52 said:

You're good with "Paul you're over thinking it". You've never met me and yet diagnosed my tendency to jump to the worst case scenario and work backwards 🙂.

Paul it was at total fluke, I've already been right once this year and I can't remember the last time I was right in twice in a year. Your wife sounds similar to mine but after 48 years you get used to it.

I totally agree the the instructions tell you so little. With my earlier model after connect it up as per car's 'Owner's Manual' I leave the charger a few seconds to settle and then you can also see what the volts reading is before charging. One press of the mode button, give it a second of time to switch to car 12v charging (a second press will get you 12V with snowflake symbol for charging when the ambient temperature is below say 5c) and that's it leave it to do all the work whilst you carry out the chores your wife has given you. It may take up to 24+ hours to get to full ("FUL").

If you have to break off the charging for any reason to use the car no worry just put he charger back on when you can and get the battery to full on the next session.

If the charger doesn't show "FUL" after say 48+ hours charging then let us know.

Just in case you don't know, if you want to you can take your car in for MoT up to a month (minus a day) before it runs out and keep the same renewal date.

Don't forget those chores you are supposed to have done. 😉

This seems to be about my level. There is one button. You push it. Then you leave everything alone and go and have a cup of tea or several.

I can beat your wife (I probably could have put that better) as mine has been in a senior management role for 52 years, all of them blissfully happy , or so it says on the directive I've just been passed....

Co-incidentally just before I read you post I opened a letter from my garage (how old school is that?) reminding me of my MOT and I'm about due for a service.

Thank you for the advice. I'll be back to the forum with my next crisis shortly.

An nice story, Paul!

I confess to a personal almost-total avoidance of DIY on the Yeti (63 plate) nowadays, and my 'next generation' have taken to EVs and roof panels (and their own 'next generation'). The AA came and replaced the (original) battery for me 18 months ago; it was a case of check old battery, remove old battery, install new battery, start engine, and finish drinking tea provided by Herself - completely hands-off throughout for me. Apart from switching engine off when AA expert had gone.

My January 2015 build Yeti Elegance is now into it's 12th year on original battery and starting first time every time.

Do you know if that car has "smart" alternator charging vs constant 14.4V ish charging? has it stop/start?.

Edited 16 April16 Apr by Johngerard

Just for interest.

New 1.0L 95BHP TSI Polo battery readings just after driving ~ 10kms after delivery, "mileage" 18kms. Car behaving exactly like the 2019 one, start/stop enabled/ operates after exactly 0.5kms even after a cold (4C) start yesterday morning. Presume its the same 59AH EFB Battery, when I enterd Adaption mode, a message to the effect, "entering advanced diagnostics,open car hood", I didn't, in case it migh be logged that I was in adaption mode and might invalidate warrenty if battery packed up within 3 years and might be used as a dealer's excuse for not honouring it, even if unlikely.

It draws a fair bit more current than the 2019 one with ignition on, 7.2A vs ~ 4.8A, usable (new) battery charge is 30A, hopefully will at least rise to ~ 35AH when SOC rises to 85%, its presently charging at full charging voltage of 14.6/14.8V under all driving conditions.

New Polo

MAS16744-IDE01836 12-volt battery-Battery current -7.159 A

MAS16744-IDE01839 12-volt battery-Battery charge status 77 %

MAS16744-IDE01841 12-volt battery-Battery internal resistance 6.8 mOhm

MAS16744-IDE01842 12-volt battery-Usable battery charge 30 Ah

MAS16744-IDE01948 12-volt battery-Battery internal resistance not normed 6.4 mOhm

MAS16745-IDE01843 Quiescent current management-Battery voltage at rest 12.5 V

2019 Polo readings first taken when car was 2.7 years old

IDE01839 Battery charge level 85 %

IDE01841 Battery internal resistance 6.6 mOhm

IDE01842 Usable battery charge 38 Ah

Think I may be in trouble here, charging now very erratic (per DVD), it only occasionally goes to 14.7V on overrun and sits at 12.5V where normally the other car never went below 13.5V. This morning, on leaving the house the voltage stayed at 13.3V on a short 10 min trip but on the way home stayed at a constant 14.7V, before the return 10 min trip I took another set of readings and the SOC is now only 64%, the alternator seems fine as it was charging initially at 28.17A, and after the 10 minutes return, at 14.4A (&14.9V), usable battery charge is now down to 19AH.

I am now charging the battery with my 5A charger, it just jumps up to 14.4V when switched on but then charges at a steady 0.81A at 13.5V, its doing this for one hour now so I will monitor the charging amps (via multimeter) regularly over the next number of hours.

IDE00019 Voltage terminal 30 14.9 V

MAS16744-IDE01836 12-volt battery-Battery current 14.433 A

MAS16744-IDE01839 12-volt battery-Battery charge status 64 %

MAS16744-IDE01841 12-volt battery-Battery internal resistance 7.4 mOhm

MAS16744-IDE01842 12-volt battery-Usable battery charge 19 Ah

MAS16745-IDE01843 Quiescent current management-Battery voltage at rest 12.3 V

Stop/Start still working perfectly!!

Edited 23 April23 Apr by Johngerard

I assume the DVD is your cheap plug in thing, and bottom figures are from VCDS, have you also confirmed figure where you can with a reasonable quality multimeter?

The 5-amp charger should increase its voltage reading as it goes along unless the battery, charger or car (or any permutation or combination) have a problem(s).

Again an assumption, you are following the charging instruction in the car's and charger's manual, for VW stop/start the charger's negative lead and clip goes to the body earth and not battery post so the controlling computer system knows what's going on.

Yesterday I charged my neighbour's battery on their 2016 non-s/s car that had a replacement AGM battery fitted a couple of years ago (presumably as the car is an auto gearbox and car get so little use) and the 4-amp "smart" charger showed 12.4v before starting and still took 10-11 hours to fully charge.

I use battery tools with computer systems as a guide not as the be all and end all, a few times a battery tester has said the battery had had it and replace, this reporting was premature and more useful life was gained from the battery by patient recharging. Of course some batteries have been flogged to death far too often and/or for too long and might not be suitable for reliable longer term use on a VW stop/start car, particular the younger cars with electronics for everything just short of wiping the driver's, er, nose. 🙃

Edited 23 April23 Apr by nta16

All readings apart from VCDS are confirmed by the multimeter, I connected it in series with the charger to get the charging current, charging leads attached correctly, + to the + battery terminal, - to the earthing post.

5 hours ago, Johngerard said:

All readings apart from VCDS are confirmed by the multimeter

Whatever VCDS reading can be checked with a multimeter or, second choice by quite away, another scan tool or battery tester, I would check.

Readings below after 2X8hour charging at 0.81/0.84A, I stopped charging when the charging current fell to 0.17A.

One way or the other this BMS is behaving completely different to the 2019 one, it will go right down to zero charging, ~ 12.0/12.2V, for minutes, resulting in the electrical load being entirely supplied by the battery, it will then return to ~ 12.6/13.3V, at least enough to charge the battery at ~ 1.0/2.0A while supplying the electrical load, it does go to 14.8V ish on overrun but not continuously, unlike the other car (still in the family) that has NEVER fallen below 13.4/13.6V under any electrical load conditions and I have never observed the voltage at lower than 14.5V on overrun.

VCDS

IDE00019 Voltage terminal 30 12.5 V

MAS16744-IDE01836 12-volt battery-Battery current -7.206 A

MAS16744-IDE01839 12-volt battery-Battery charge status 86 %

MAS16744-IDE01841 12-volt battery-Battery internal resistance 7.2 mOhm

MAS16744-IDE01842 12-volt battery-Usable battery charge 33 Ah

MAS16745-IDE01843 Quiescent current management-Battery voltage at rest 12.6 V

MAS16744-MAS22232 12-volt battery-Battery aging: charge-related 92 %