I have a question for the technically minded out there. Following an altercation with a step-ladder, I now have my left wrist in a cast for the next 4 weeks. Being unable to drive, I'm concerned about maintaining the battery. I don't have a charger, and probably wouldn't have the dexterity to connect it at the moment. If I were to start the engine and leave the car idling once a week, say, would that be adequate for keeping a reasonable level of charge in the battery?

Hi, I used to have a maritime career and would frequently park my car up for 3 weeks plus.

I don't ever recall having a battery go duff whilst sitting. I used to have a fair run from home to the place of work and so the battery would be pretty much full when I parked up. Bear in mind that the alarm was powered up all of this time, though obviously doesn't use much, so I would say that if your battery was in good nick, it should be OK. Staring can take some charge out of a battery, not sure how long it would take to make up that charge when idling.

It should be fine i reckon ,people park cars up in airport car parks for just as long and have no issues on return 👍

45 minutes ago, RCC49 said:

If I were to start the engine and leave the car idling once a week, say, would that be adequate for keeping a reasonable level of charge in the battery?

That might actually make things worse. Many modern cars charge the battery only when the car is going downhill or decelerating to a stop, or else when the state of charge is very poor. The purpose of this is to save a bit of fuel, as the alternator is harder to turn when it is called on to produce electricity.

Thanks for the replies. I'm reassured that I don't need to worry.

I regularly used to leave my cars for 6 weeks when I went to warmer climes for my 'winter break' !

I only ever had a problem with one, a Seat Exeo which was 3 yrs old and I'm sure the battery was on its way out. That one didn't even have enough juice to activate the central locking, I had to use the emergency key!. All the others have started on the button...

I had my licence suspended (health reasons), and that was me off the road for 3months. My diesel Citroen C4 started first time, when I got my licence back. Had not touched it, in those 3 months.

We regularly leave our Karoq for 6 to 7 weeks while at our house in France. Starts perfectly when we return and that's on a nearly 7 year old battery so you should be fine.

I do appreciate all of the helpful and supportive replies.

If you have a car made in 2024 or 2025 it won't be a good idea to leave the car parked up, locked up with alarm on for 4 weeks same for a 2022 made car but possibly less so.

It also depends on how high or low instate of charge the battery is when you first parked it up as it will only get lower so a lower start point means a lower end point. The battery likes about 20C and starts to discharge itself more at higher temperatures.

Plenty on threads on this site alone about flat batteries from cars being parked up and all the unexpected warning lights and messages, unseen error codes and issues from the battery being low but the headlights still seem bright enough and the engine starts. The computer systems and programs don't like the battery in too lower state for them (plenty of threads on the site exampling this).

Best on to (get someone to) connect the battery to an appropriate charger maintainer following the instructions in the car's 'Owner's Manual' and for charger maintainer and to fully charge the battery and the maintainer will then keep it topped up. A good quality 4amp (that's all you need) example is available from Lidl for £15.

Alternatively you (or someone else) could disconnect the battery following the instructions in the car's 'Owner's Manual', check what might (not all things they list are always effected) need resetting after reconnection, normally if you fully close all windows and sunroof, you only need to reset time-of-day clock, petrol/mileage, seats.

Running the car will charge the battery but of course you need to have the electric consumption lower to get more charge back, air-con, heated anything, lights all off, don't turn steering wheel, start/stop off and then unless you leave the engine running long enough to get the oil (not coolant) temperature to 90C+ it won't be best for engine oil or engine.

You may get away with leaving the battery 4 weeks, or a lot more perhaps (if not a 2024/5 car) but if the battery gets too low, even if the engine starts, the battery may not fully recover from this if it gets too low and shorten its reliable useful life. Not to turn up the misery but if the 4 weeks extends the need for recharging increases.

As always each to their own.

HTH.

And if I were to run the engine with everything switched off, how long do you suggest?

If it were me I'd run the car for about 2-5 minutes past the oil (not coolant) temperature was at as high as it's going above 90C.

If the battery is very low you may need to briefly turn the headlights on to nudge charging into action shouldn't be needed but it won't hurt to do it even if battery isn't too low, remember only briefly If you want low usage items on like the radio to keep you entertained , say after the coolant temperature start to rise a bit or near 90c fine but bear in mind if the entertainment system is also doing TwatNav, running your phone etc. this is more electric usage drawing out when you want electric in. ETA: you could put the windows down, run the blower perhaps, if that makes it more comfortable to be in the car, I don't mean going to extremes to save nanos of electricity.

If you do it today then once a week or to 14 days (depends how low the battery charge was/is) until you can drive the car again you should have things better.

This only deals with the battery and engine, the tyres, brakes, transmission, etc., aren't getting any excise so you want to do your driver/owner maintenance checks before you drive the car next.

Whatever age your car if you are keeping it more than a few years and don't frequently do reasonable length journeys and you prefer reliability and longer useful life of the expensive 12v battery in VW vehicles to paying for new replacement (and 'coding' in) then an appropriate battery charger maintainer and occasional preventative rechargers will probably be necessary. As I put these don't need to be elaborate or expensive (unless you prefer such stuff) the ones Lidl (and others) sell are fine, lower (amps) and slower recharging is generally better than high and fast. Just another example. - https://shop.ringautomotive.com/rsc904-4a-smart-battery-charger-maintainer.html

My wife's 2015 Fabia on a preventative recharge on a very cold winter's night through to morning, 4-amp charger, 14 or 15 hours to get to fully recharged (in two sessions, car was need to drive 2 miles to work and 2 miles back that day). Whilst the charger was doing its job I was watching telly, listen to radio, sleeping - this is the only type of farting about with cars I don't mind. 😁

Edited 13 May, 20251 yr by nta16
ETA:

If you were able to get someone to check the state of charge of the battery before you charge it you'd know how much is needed to help it, multimeter probes on the battery terminal posts is my preferred more direct readings (engine not run of course) and allowing a 0.2-3v drop from the car's systems being active.

VW (figures)

 

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

Thanks for your suggestion.

4 weeks is nothing, don’t worry about it.

If it's a 2022 car and the battery is reasonably charged it will get through it (and probably longer) but better to take the opportunity to fully recharge the battery though as the car's doing nothing else.

If it's a 2025 car it'll get through it (and probably) but it might be more noticeable and perhaps have a permanent weakness from the experience.

The electric loads on newer cars is not like in the past, use, abuse and neglect of car batteries has become a lot more noticeable so much so that it's been reported on this site at least one Dealership offers a battery charging service, for £40. and it remains the number one cause of breakdown call outs. It's very rarely the actual battery at fault most often to do with the car's driver/owner, occasionally a charging system issue.

The 28.2.2022 'Owner's Manual' even has a section for 'Using the jump starting cable' (must be for some of you lads here 😁).

The following is from the '12 volt vehicle battery' section. -

And from the 25.11.24 'Owner's manual'(the latest one listed 'Protection against discharging the 12v battery'.-

As always it's each to there own, it's only advice (from decades of experience of dealing with neighbours and friends batteries. Leaving a 20220or 2025 VWŠkoda standing unused with the battery connected up for 4 weeks, particularly if it's not in a reasonable state of charge, will have an effect on the battery and depending on the initial state of charge, it's age, use/abuse/neglect may have a permanent effect. These batteries aren't cheap (then there's the VW 'coding' if that's a concern.

But as always it's each to there own.

2 weeks standing (unlocked) from full charge can see our 2024 Karoq battery down to 35%..........still more than enough to start the car but I consider that to be quite a drain?

2 hours ago, Berisford said:

2 weeks standing (unlocked) from full charge can see our 2024 Karoq battery down to 35%..........still more than enough to start the car but I consider that to be quite a drain?

Does seem a lot but - was full charge 12.7(8)v 100% from a battery charger or the car's stop/start perhaps 80(?)% full charge 12.4(5)v If car stop/start full charge of say 12.5v and if you allow a 0.2-0.3v drop for the car's systems working it could show 12.3v-12.2v. 12.2v is only 50% on the VW chart before any drain so 35% (at say 12.05v) seems less bad.

Getting the battery too low and/or too often will shorten its reliable life. Hence VW going from saying change the battery at 5 years (far too premature for most then) in the Owners Manuals to change the battery at 4 years in later Owner's Manuals and why owners of 2020/1 and newer VW owner are having to change at even 3 years.

If the car is not to be kept for many years, and/or the owner doesn't mind buying an expensive battery (and coding) it doesn't matter.

If a battery is often low the alternator has to work harder so more wear, again this doesn't matter when the car is not so old.

Some seem to rely on an expensive jump-starter pack as back up, another unnecessary big-boy-toy if not in business. a £30 charger maintainer and very occasional preventative recharging suits me better.

Then there's the home or roadside 'breakdown' rescues . . . followed by £200+-£300+ distress (premature) battery purchases, then or later.

4 hours ago, nta16 said:

Does seem a lot but - was full charge 12.7(8)v 100% from a battery charger or the car's stop/start perhaps 80(?)% full charge 12.4(5)v If car stop/start full charge of say 12.5v and if you allow a 0.2-0.3v drop for the car's systems working it could show 12.3v-12.2v. 12.2v is only 50% on the VW chart before any drain so 35% (at say 12.05v) seems less bad.

Getting the battery too low and/or too often will shorten its reliable life. Hence VW going from saying change the battery at 5 years (far too premature for most then) in the Owners Manuals to change the battery at 4 years in later Owner's Manuals and why owners of 2020/1 and newer VW owner are having to change at even 3 years.

If the car is not to be kept for many years, and/or the owner doesn't mind buying an expensive battery (and coding) it doesn't matter.

If a battery is often low the alternator has to work harder so more wear, again this doesn't matter when the car is not so old.

Some seem to rely on an expensive jump-starter pack as back up, another unnecessary big-boy-toy if not in business. a £30 charger maintainer and very occasional preventative recharging suits me better.

Then there's the home or roadside 'breakdown' rescues . . . followed by £200+-£300+ distress (premature) battery purchases, then or later.

That was from a battery charger - as I was curious about how high the cars 'system' charges I checked yesterday after a 200 mile run - I gave the car 30 minutes to settle and then run a basic test - 'State of charge 98%' - 12.64v - 395amp out of a 420 rated battery.

So the car's charging system does top up much higher than I thought - I did a similar test on our Superb and that (IIRC) only showed 66% - although that battery was replaced under warranty.

Either way, I wouldn't like to letting either of our Skodas stand for 4 weeks - my trusty old 2010 Golf however..........not a problem.

In my garage / yard I leave the Karoq unlocked when I know it's not required for a couple of weeks or so because I've convinced myself it doesn't 'run down' as quick - I'm thinking the Kessy system must drain a bit whilst constantly awaiting / searching for a command?

If possible you want to give more than 30 minutes for surface charge to dissipate a few hours or next day, yes there will be a very slight drain from car just sitting but not enough to count.

Sounds like you might have had the stop/start switched off or not a journey where it could really activate perhaps. I've not tested how high the state of charge is with stop/start on, suggested is 80% but I've not seen that written anywhere I've seen and it doesn't worry me as I will always fully recharge with the charger when I feel like it (such easy work anyway unlike most ,for me, loathsome PITA car work.

Until my wife got the VW product I've only once (in 48 years) ever had to recharge a battery on my own car, and I've had 20-50 year old cars, and that one time was when I flatten the battery trying to start a V8 engine I thought I remembered and knew the firing-order so didn't marking things up, a Billy-big-*******s ego error I never made again.

Proximity keys is another "aid" feature I can well live without - do make sure the keys are in a tin not seeking out the car particular the key not in current use. Never have a "spare" key always alternate the use (in whatever fashion/time-period that suits you) both (or all) so that batteries, remotes, cylinder locks and keyblades all get more even wear, plus it means you never lose or mislay keys or "spare" and you know the batteries aren't flat.

My neighbour's 2021 Nissan was parked up for 2-3 months before I persuaded him it'd need charging to be sure it could be collected for mot and annual service, to my surprise it started but despite using my old trusted chargers I couldn't get the battery fully charged even off the car. I recharged it a couple more months later and a bit after that a Dealership/garage bought it, any money you like they sold it with the short life battery. Took a bit of effort to drive off the rust on the brake discs too, first time was empty dual-carriageway stuff and that didn't clear everything.

If the battery is fairly well charged at the start, then something like this should help to keep it happy. Assuming that the weather plays nicely, and your car isn't parked under cover: https://www.halfords.com/motoring/battery-maintenance/battery-accessories/halfords-20w-solar-maintainer-191251.html

On 13/05/2025 at 06:13, sussamb said:

We regularly leave our Karoq for 6 to 7 weeks while at our house in France. Starts perfectly when we return and that's on a nearly 7 year old battery so you should be fine.

That's because me and a mate "borrow it" to cross the county line, if you get my drift, whilst you are away. So it has a good run every week...... :-)

On a serious point, I am looking at one of these https://shop.ringautomotive.com/rsc906-6a-smart-battery-charger-maintainer.html as they are the same cost as people say the Škoda main dealers charge for doing the same thing. Ie a top-up charge/recondition. I note it comes with croc clips and a set of O-ring terminals to an in-line plug. So I can put the o-ring terminal on the car permanently for a good connection, and it is easy to plug in the maintainer.

Edited 22 May, 20251 yr by chills

20 minutes ago, JohnArm said:

If the battery is fairly well charged at the start, then something like this should help to keep it happy. Assuming that the weather plays nicely, and your car isn't parked under cover: https://www.halfords.com/motoring/battery-maintenance/battery-accessories/halfords-20w-solar-maintainer-191251.html

Have seen these on a few local dealer’s forecourts, on the cars that don’t seem to sell quickly. Which probably means they have poor batteries - worth getting a new battery in the deal!

My son loaned me one of these https://www.amazon.co.uk/gp/aw/d/B00FC42HAA/?_encoding=UTF8&pd_rd_plhdr=t&aaxitk=6d826fb3716570b2cb33d46862f5d636&hsa_cr_id=9828796380502&qid=1747907534&sr=1-1-e0fa1fdd-d857-4087-adda-5bd576b25987&ref_=sbx_be_s_sparkle_mcd_asin_0_title&pd_rd_w=uyDxT&content-id=amzn1.sym.a18126b6-9995-4982-ac44-f6ce57aa9bed%3Aamzn1.sym.a18126b6-9995-4982-ac44-f6ce57aa9bed&pf_rd_p=a18126b6-9995-4982-ac44-f6ce57aa9bed&pf_rd_r=5F0D3Y1Y52XQTAGMYQPJ&pd_rd_wg=JqARp&pd_rd_r=0cea2770-7dc1-451d-9649-acc6e24ecaec&th=1

It has an adapter which plugs into one of the 12 volt "cigarette lighter" sockets, either in the centre console or in the boot. I chose the centre console one and left it connected for about 24 hours, and that did the trick.

35 minutes ago, chills said:

That's because me and a mate "borrow it" to cross the county line, if you get my drift, whilst you are away. So it has a good run every week...... :-)

On a serious point, I am looking at one of these https://shop.ringautomotive.com/rsc906-6a-smart-battery-charger-maintainer.html as they are the same cost as people say the Škoda main dealers charge for doing the same thing. Ie a top-up charge/recondition. I note it comes with croc clips and a set of O-ring terminals to an in-line plug. So I can put the o-ring terminal on the car permanently for a good connection, and it is easy to plug in the maintainer.

That ring charger is the same as what i have ,its a good bit of kit .