New car flat battery

Unusual for a 'new' battery to fail like this, but not impossible. Could be something not turning off when it should, eg the interior boot light. I'd be asking the garage to check the current flow when everything is turned off (or as much as possible with modern cars). 

Faulty battery.

Faulty alternator.

Faulty rectifier.

Something leaching power when the engine's off.

If I were playing Parts Darts, it's probably the battery.  They don't like being deep-discharged.

Take it to an auto-electrician.  I had a similar problem with an old car, it was in and out of the garage for months.  I wound up taking it directly to Lucas who correctly diagnosed it inside of about 40 seconds.

Posted by: jonba

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They said it looked fine but it clearly isn't.

What does that even mean? My first question would be, did you check the voltage before actually starting it? I have a little device that plugs into the 12v aux socket which shows the static voltage before starting, I used to be given a list of cars in storage at my previous job, and used it to check the battery state of cars that had been sitting for a length of time. 
I would have thought the garage would have done something similar.

Personally, I would expect a car that’s only a year old would have a battery that’s capable of maintaining a charge even at low temperatures for several weeks at least without the voltage dropping to a point where it won’t turn over.

When my Octavia’s battery wouldn’t start the car when I was camping in South Devon, the AA bloke checking it said it had about half the original capacity; it was the original battery and the car was about 13 years old!

Get the garage to actually check the voltage, then properly check the charging system, particularly the alternator, I’m no mechanic, but I would suspect that the issue lies somewhere there.

And whilst you sort this get a charger pack so that you don’t get stuck at the side of the road

Any recommendation on a charger pack?

Reluctant to take it to somewhere that will cost me money at this point with it still being under warranty. Will be a bit more specific in the questions and responses. I was out of the country when they had it so communication was limited. Just had the service receptionist give me the notes - not the specifics.

The first breakdown guy did do some diagnostics. Can't remember 100% of the details but it was low voltage causing the issue. It was charging correctly when idling. I think he looked for use at the same time and said that was normal.

Any recommendations on a charger pack? Do the cheap halfords ones work. It would be worth having as my wife has an old horsebox too which has had issues on occasion (but that is an old van not driven all that much at the minute).

Posted by: richmars

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Could be something not turning off when it should

Very obvious thing to check.

I am not a mechanic.

I am however reasonably confident that if you rock up to a mechanic with a list of things that you demand they check based on something you've read on a bicycle forum on the Internet posted by people who haven't even seen the vehicle, it will get their backs up.  Explain the symptoms as accurately as possible, the subsequent diagnosis is their job.

The 1st breakdown guy was from VW and talked me through some of it. The battery had low voltage but as far as he could tell from his diagnostics it was charging and discharging normally (he mentioned the alternator functioning ok and no phantom discharge). He spend around 30 minutes monitoring this.

Checked the garage job sheet and against "Customer reported recent low battery issues" it has "Battery ok". No idea what diagnostics he did but this wasn't the specific reason I dropped it off I just asked them to look at it. Communication was limited as I was out of the country and picked it up when the service centre was shut.

Will talk to the garage on Monday. It's new, so I will go back to them before going elsewhere as I want this sorted under warranty. Will try and be a bit more specific and make sure there is more feedback on what they test this time. Two flat batteries in about a month is not normal so they need to explain what happened and why it won't happen again.

Do you need to spend much on the charger packs or are the cheaper ones ok? Might be something useful to have around as my wife drives an old horsebox which has needed jumping on a couple of occasions.

The first time we hadn't driven for a week and it was very cold.

That's not an excuse on a 12 month old battery.

You're stuck in a layby..... If it's letting you down while you're driving then it's not charging properly.

In warranty = new battery and get a jump pack off Amazon - ridiculously handy to have.

I have a Noco Boost GB40. Never needed to use it but gets good reviews.

https://www.parkers.co.uk/car-advice/upgrades-accessories/best-car-jump-starter-power-packs/

+1 for Noco. I have one and I have used it more than once. From just a click when turning the key to instant start when attached. Although not cheap it was worth it for not getting stranded twice. Recommended

oh yes, I did try to use it to help my neighbour start her diesel Fabia and it didn’t work-the internal protection cut in. The local garage told her that the battery had a dead cell so a jump pack unlikely to work in that situation?

Is it flat eg turns over but weak?

Or simply nothing, no dash lights, hazards etc? Eg completely dead, zero power

It can't hear it ticking over - the dash just goes nuts and all the warning lights/messages come on. One of the messages is start the car to charge the battery but that feels like it's a bit late as it won't start!

Will do some reading on the jump packs to see if they'll work on a larger van. Thanks for responses.

In any case I'm phoning the garage on Monday to sort out another look. Hopefully a bit more digging this time might reveal something and it is a simple fix. Given my phone can do battery diagnostics quite well, I assume they can look at battery history. And see what's happened over the last few days.

Any obvious problems/fixes?

Not at 12 months old, no.

There's stuff to check like terminal tightness, corrosion and security of the earth strap, but I'd leave it up to the main dealer to sort

You shouldn't need a jump pack either. You might be better to invest in a charger and give the horse box a monthly top-up

If OP is sitting in a lay-by does that imply that the battery died during a journey? 

No, we had parked for a walk and it wouldn't start when we got back 4 hours later.

4 hours - that's as good as it dying during a journey. You don't do a load of very short trips do you? Gradually lowering the voltage by not topping up the starting drain.

If you have a multimeter it should show about 13 volts static and nearly 14 with the engine running/being charged. That doesn't tell the whole story, but it's a start. 

Just bought a Noco Boost GB20 on offer on Amazon for about £64. Going to live in the van's boot just in case we flatten it when off camping

To jump start the horse box you'll probably need a bigger pack than for just the Caddy.

Horse box would probably benefit from a solar trickle charger/conditioner (even if you have mains, there is less issue of driving off and forgetting it's plugged in). The Caddy shouldn't need a jump pack.

Sounds like my old Audi A3 - something Electronic would bleed the battery every week or so.  I suspected a door lock, as i eliminated most everything else. 

 I got sick of driving round with a spare battery and sold the car .  

Posted by: jonba

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Do the cheap halfords ones work.

I have a Halfords one - it's been fine, starts a T5 having been sat under the passenger seat for months.

Caddy? If it’s the same as the ford offering, it seems pretty glitchy electronically.

However to drain a full healthy battery in 4 hours is going to need a something like a 15amp load, way more than the interior light being left on.

So it’s either a big parasitic load or a charging circuit/battery issue.
FWIW I’ve had brand new vehicles with loose battery terminals and loose alternator terminals, obviously these have been checked.

I have spent a good deal of time chasing an intermittent low voltage issue on a much older car that turned out to be a poor connection on the starter motor. 
Not the first place I’d have looked.

I’m sure the garage will get to the bottom of it.

Due to not driving for long period sometimes, I had to jump start my car rather often but the battery is alright except it drained easily.  Fed up with having to trickle charge when I need to drive, I bought a battery pack jump starter.

I bought this from Argos, Ring 12000mAh Ultraboost Jumpstarter & Powerbank but not easy to find as they are sold out at most locations near me.  Had to travel to another town to get it rather than order online.  I bought the highest mAh as possible and it is cheaper than than other brands of the same capacity.  Before using it I charged the power pack to 100%.  The Powerbank works perfectly and looks solid. 

I then attached it to my car battery, the engine wouldn't turn before that just "ticking" sound, and jump started it in one go.  Checked the power pack it was drained by 7%.  My car is 1.6 litre Petrol.  Then drove it for a while and all was fine.  Then I stop driving again for another two weeks ... arrghhhh ... bought a new trickle charger but still not use it yet. Let's see if my car can start tomorrow.

+1 on Noco. I got one a few years back after I was stranded on a camping trip at a remote site with doors and stupid electric boot being used for two days without moving the car. 

I bought the biggest option so that it will work on V8s etc. May as well be able to help out other people too.  

I've used it several times, for charging phones as well as starting cars. Great piece of kit.

We have a noco40, incidentally for the horse box (basically a Peugeot Boxer which doesn’t get used much in the winter) and it will start a big old battery. Useful things to have around. 

Batteries are funny things at times. Sometimes if they go fully flat they need special recharge regimes (I have a car with a 12v LiPo battery - has to stay on trickle charger all the time when parked), even AGM batteries can be like this. Did you recharge yours after it went flat.

No real help whatsoever probably 

I’m convinced that out Merc has some weird setting that if you drive it in ‘eco’ the battery doesn’t get charged as you drive. 

when we bought it Merc replaced the battery for free after about a month of me owning it. About 2 yrs later the same low battery issues started. The garage could find no issue with battery or anything else but it was not holding charge.

Read on the interweb that someone in an identical car was having similar issues, and they were convinced it was drive mode.

So now I just drive in ‘comfort’ and no more low battery issues 

I had similar issues with a similarly aged Golf (albeit a long time ago - it was a 2005).  

No issues with battery or alternator on testing it was found to be one or more of the control modules in the car allowing/causing it to discharge when parked up.  

Car was in the dealer for a week under warranty for diagnosis and repair.  

While I know it's a much older car and a long time ago those symptoms pretty much match.  

If it's under warranty just lean on the dealer.  

I need to talk to the garage again but not sure what to do.

To go back to this question. You loudly mention to the Service Dept that it has left you stranded again. You then refuse to collect the car unless they can convince you it's sorted. If they give you any sort of nonsense, you phone the nice people at VW Customer Services and tell them that their dealer is being rubbish.

So they've had it most of this week and found nothing. Battery behaving as it should. Whole system charges ok at idle and driving and doesn't discharge unusually under same conditions.

Doesn't explain why I've had multiple issues though. They can't do much else.

I'm left with leaving it at the garage to see what happens (but I doubt they will find a cause) or picking it up, using it and hoping it doesn't happen again.

Neither of these is ideal but I'm leaning towards the latter.

So they've had it most of this week and found nothing. Battery behaving as it should. Whole system charges ok at idle and driving and doesn't discharge unusually under same conditions.

Doesn't explain why I've had multiple issues though. They can't do much else.

I'm left with leaving it at the garage to see what happens (but I doubt they will find a cause) or picking it up, using it and hoping it doesn't happen again.

Neither of these is ideal but I'm leaning towards the latter.

I'd get a new battery stuck on.  New Caddy's are very finicky electronically - the battery actually has to be coded to the car, so you can't just grab one from Halfords.  It might give you peace of mind.

Did the garage put the battery on their diagnostic charger?
After my battery issues last week, my ex mechanic neighbor said that after we jumped my truck, that even a long drive may only surface charge the battery, not restore a full deep charge.
According to my local motor factors, who have replaced a few batteries under warranty ( I had a parasitic drain, plus I often forget to unplug my always on dashcam for several days), Workshop chargers will also identify how cells are behaving, not just if it is ok 'cos it's 12v.

So they've had it most of this week and found nothing

Kicking the can down the road till the warranty expires?

Well, I nearly got stuck at Tesco car park few days ago when my car wouldn't start. Before that the engine was struggling to turn and only get "tick tick" sound, but after 4 attempts it started so I drove a long way to Tesco.  Finished my shopping and the car wouldn't start at all. Completely dead.  Luckily I had my Ring battery jumper pack with me and after 3 attempts the car started (I forgot to press the boost function of the batter jumper pack).  Without the jumper pack, I guess it would be an expensive night for me to call out my garage mechanic.  Now, I just need to trickle charge my battery again but it was too cold to do so for the past few days.    

Fun times. It wouldn't start this morning. Same battery/power issue.

It'll have to wait to Monday before I can phone them.

Anyone dealt with something like this before and got any advice. I'd prefer not to have to pay for legal advice at this stage but new cars are expensive.

I'm going to get it taken in. Last time they mentioned a replacement vehicle which I will now need. My plan is to ask them to replicate/diagnose the root cause of the fault and repair it. If they can't do this I can look to the consumer credit act (I think) as I'd like a working vehicle (replacement) or refund - it has a 2+ year warranty but I believe I have statutory rights above that which are more powerful? If they can give me a similar replacement vehicle I'm not too fussed how long it takes them. But I can't be playing roulette as to whether it starts every time. Bought outright if that makes a difference.

OK.

How new is new, when did you buy it, where did you buy it from (dealer, private sale, something else), how did you pay for it and when did you first report the fault?  All of those things may affect your rights.

If the answers are "from a dealer" and "within six months of purchase" then read this thread as it'll save me a boatload of typing.

Posted by: jonba

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consumer credit act (I think)

Consumer Rights Act and Consumer Credit Regulations are two different things.

Also, 

In this specific instance I would be especially wary of relying on warranties because they set the terms and it's completely plausible that they could go "sorry mate, the battery is a consumable."

You didn't respond to this question earlier on, I still think it's relevant. 

You don't do a load of very short trips do you? Gradually lowering the voltage by not topping up the starting drain.

Doesn't explain why I've had multiple issues though. They can't do much else.

Years ago a neighbour had a Volvo V50 with a similar issue. Two new alternators fitted, no problem found

Long story short, it ended up plugged into the internet and someone in Sweden reprogrammed the alternator ECU remotely

I have it in writing that the battery is not the issue. If it is and they replace it and it works, great it is covered in the warranty in any case. What I want out of this is a working reliable vehicle in line with what you would expect for an 11month old with 5000miles on it. Bought new from the dealer I'm currently working for. Took delivery end of March 2024.

The issues is that it doesn't start. I do not know the root cause and they've not been able to identify that which is the main problem. It appears like the battery is going flat. Over the period of a couple of weeks or even less. I don't know if that is because it is draining or it is not charging - I expect the dealer/VW to figure that out as they engineered the thing and have the expertise. The last time they couldn't find any problems when they had it for a week.

I probably drive it a couple of times a week. Normally 30 minutes to 2 hours at a time. I picked it up 8 days ago from the garage where they had charged it. I drove it 2x1 hour on Sunday. My wife drove it 1 hour Tuesday. It wouldn't start this morning. There is definitely something wrong with it.

They are working to help but I'm slightly worried what happens if they can't find the problem as I would like a reliable vehicle and not be £10'000s out of pocket. No real experience of a purchase this size going awry though so a bit nervous.

This sounds painfully similar to my old A3 which would flatten the battery every week or so.  I came to the conclusion eventually it was a rear door lock that would sometimes stick on and flatten the battery.   

It wasn't the alternator etc.  It wasn't leaving the lights on.  It took a garage forever to come to the same conclusion as there wasn't an error code as technically nothing was bust. 

It was a p.i.t.a. and i eventually traded the car in.  Good luck! 

I had the fun of my car struggling to start when cold, but always did, except the day we moved house. It would also start fine every single time after that initial dead cold struggle. Jump leads didn't work, but a battery pack did. Drove straight to Halfords where they tested it with 2 separate checkers and the battery was 95% full and no issues. Booked into a garage for an investigation and they came back saying there was a dead cell in the battery. Only driven once in the 1.5 weeks since a new battery was fitted, but started fine.

You haven't left an iPod or similar plugged into the cigarette lighter? That can remain on and will drain power.

No I've been meticulous in checking things since the first time.

When they hooked it up to the diagnostics they couldn't see anything drawing too much power. Their challenge was replicating the fault in the week they had it last time. It's a bit of a suprise it doesn't have more monitoring built in given the tech in there. Cant even see the battery level.

We've been through most options now. The first time a guy from VW breakdown came out and looked at it. Since then two trips to the garage. So plenty of suggestions to check and correct but the problem persists.

The other thread is useful and the motor ombudsman website. In terms of refund etc.

I want a working/reliable car so happy with a fix. A refund would be a pita because we waited nearly 12 months for this one to arrive! There's also a limited number of similar vehicles available new.

That and I need a van the next two weekends!

Firstly, good luck OP, what a rubbish situation to be in.

Some random points in no particular order:

MIL had a Japanese car that needed the key turning back an extra click when parked up, or it went flat.

My mum had a battery drain that turned out to be a cracked spark plug, no idea how that worked but new plugs fixed it.

Cut off relay in my current (sorry) Kuga seems to be non-existent/broken, car doesn't shut down fully unless the car is closed up, and no the interior lights aren't on!

Many main stealer's techs aren't necessarily the best techs, just the highest prices. What you want is an older tech who is still engaged with the modern technologies, they have the experience to test things that make no apparent sense but which have worked in the past.

Lastly in this stream of consciousness there does seem to be a reluctance to request help from head-office, we had a Skoda with a weird infotainment issue, kept getting faffed about until they finally rigged it up to the factory and hey presto - new firmware fixed it.

Just ordered a Noco Boost Plus GB40 from Costco for £48, here's hoping it wasn't too good to be true - I'll report back on that! 

I would be interested to know what "diagnostics" the dealer has done. Just checking the voltage when the car is running and when switched off isn't enough.

I am not that great mechanically but Google threw up this article where the guy seem to know his stuff. I am not convinced every main dealer tech would be checking as well as this.  Any good specialist auto electricians in the area. You shouldn't have to do it for a new car but if paying a couple of hours labour solves the problem?

https://www.team-bhp.com/news/idiots-guide-tracing-parasatic-battery-drain-modern-cars

Posted by: jonba

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Took delivery end of March 2024.

The issues is that it doesn't start.

When did you first report the problem to the dealer?

+1 on the Noco jumper packs.

My Kuga, whilst otherwise has been pretty reliable so far in 3 years of my ownership (7 years old total), does like to kill batteries. Even without faults.   I'm on the 3rd battery (at least) in its 7 year life.  Partly because every time the car is opened, all the computers boot up, and interior lights come.on - that you can't then turn off !!!  Camping is the worst as of course you're often in and out the car, + if you have a dawgie in the back ans leave the tail gate open  side lights, tail lights and interior lights are on constantly, as well as the computers booting up for 10 or 15 mins.  After a stranding because of this, I got a Noco booster (went for the  GB70  - bigger than probably needed for a 2 litre turbo diesel, but  I'm on for having plenty in reserve if I need it). 

For the reply thst said the neighbours car battery was dead- not sure if you know  but the Noco has a 'polarity protection' meaning it's looking for + and - on the battery (so you're not connected the wrong way).  If the car battery is really dead there's not enough voltage for it to detect, it won't boost the car.  You then have to use the over-ride button (red exclamation mark) to bypass the polarity protection.  Think it has to be held for a couple of seconds (to avoid accidental pressing). 

Posted by: robertajobb

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For the reply thst said the neighbours car battery was dead- not sure if you know  but the Noco has a 'polarity protection'

Sorry, perhaps I should have added more detail. Yes, tried that after it wouldn’t even turn over . After overriding the protection It would turn very very slowly but not enough to fire the 1.9 diesel. The Noco then got quite warm so we stopped.

I’m convinced that out Merc has some weird setting that if you drive it in ‘eco’ the battery doesn’t get charged as you drive. 

That's not actually that unusual. The eco mode will reduce drain through the alternator. What it shouldn't do is allow the battery to get below a safe set point. This gets difficult when the battery is old, cold or knackered.

FWIW a lot of dealers just test the current and voltage being delivered instantaneously (or over a few seconds) and then say the battery is good. You need to be looking at it over a longer time and/or with a known load being applied. They won't do this, they want you to stick a new battery in at ~150 quid.

NB, if the battery has been replaced and needed coding (but they didn't) the new battery will quite possibly be knackered.