May 2022 Update

[Southern Lad]

As mentioned by Terryp before, if washing the car over the weekend, switch on the ignition whilst doing it (as long as you're in attendance). This allows the traction battery to send a charge to the 12v battery when it needs it and if the traction battery gets a bit low, the engine will start and give that a charge.
This is all assuming you're getting a HEV, as it appears that it's only that model that if afflicted.

I'm I missing something here when cleaning the car?

I hoover it out with 1 door open at a time for each area, ignition is switched off & key inside faraday pouch in garage so car unlocked. That takes 20-30 mins. I then close the last door open and leave unlocked as it is and proceed for the next 2 hours or so to give a wash, rinse & polish. After I've done all this when I get back into the car I have no issues battery wise at all!!!!!! Everything works as it should... (hopefully that's not jinxed it)

Ps Oldman. Sorry to hear the problem wasn't solved but I guess you already had an incline that would be the case....

[Unimatrix]

I will be an everyday user, at least Monday to Friday anyway but most likely most days.

Whilst it's not set in stone, generally I find that if my car is left unused and completely untouched for 2 days everything stays the same.
As mentioned by Terryp before, if washing the car over the weekend, switch on the ignition whilst doing it (as long as you're in attendance). This allows the traction battery to send a charge to the 12v battery when it needs it and if the traction battery gets a bit low, the engine will start and give that a charge.
This is all assuming you're getting a HEV, as it appears that it's only that model that if afflicted.

To be honest, i just decided on getting the petrol only version of the car. Still deciding if i've made a mistake in not getting some sort of hybrid version.
However i am getting the Ultimate spec to keep myself happy

[old man]

Still deciding if i've made a mistake in not getting some sort of hybrid version.

Maybe, maybe not. I got the hybrid because I wanted the extra power it provides and I didn't want a plug in.
As you're seeing, the hyrid is bringing with it problems that other versions don't have. It is probably a little more economical than a petrol version, but then the hybrid costs more to buy, so swings and roundabouts.
If you haven't already seen the thread, the new Tucson comes with a GPF (Petrol Particulate Filter) which is the equivalent of the DPF in diesel cars. THe GPF is touted as not giving the problems that DPFs do/did, but it appears from this forum and another one that some petrol only versions (so far) are getting clogged GPFs, which then require a trip to a dealer to have a forced regeneration to clear it. Some dealers are doing this for free and others are charging.
From the patchy chat with not enough detail that is rife on forums, it would appear that this affects cars that are doing predominantly short runs, as it does with diesels. so if you're doing trips that are long enough to get the engine up to a good operating temperature (and motorway driving helps here) then you hopefully shouldn't be affected.
Hyundai have issued a written directive on how to treat your engines in the hope it will prevent GPFs clogging.
Some of those that have been afflicted claim that Hyundai are selling cars that aren't fit for purpose and they have a point, as when you purchase a car you should be able to do whatever sort of driving you want, but it would be helpful if Hyundai (and maybe others) should inform prospective buyers, that if they are mainly short trip drivers, they are likely to have GPF problems.

[terryp]

Forgive me if I've posted this before (at my age I need to do everything twice (well, almost everything!).
It's a clip from a Toyota magazine and it's the one that prompted me to carry out my "wash and wait" routine when washing my car.

"To recap, Toyota hybrids generally contain two batteries: a 12-volt battery (which powers systems such as the headlamps and audio) and a high-voltage hybrid system battery (which supplies the power to start the combustion engine and drive the electric motors).
The simplest way to maintain charge in both of these batteries is to simply go through the normal start procedure: press the ‘Start’ button with your foot on the brake and ensure the ‘Ready’ light is illuminated on the dashboard (you don’t have to keep your foot on the brake thereafter, but ensure your vehicle’s transmission is in ‘Park’ and the parking brake is engaged).
We recommend you put the car in ‘Ready’ mode for about 60 minutes before switching it off again and repeat the process at least once a week, providing you can carry out this procedure while adhering to the government’s advice regarding social distancing and Coronavirus (Covid-19). Please do not leave your car unattended when it is in ‘Ready’ mode."

It also states that this is more necessary in low mileage cars. That goes for mine which rarely gets a good run to charge either battery.

This advice has been repeated in other similar magazines so although the problem doesn't seem to be confined to Hyundai, it would seem that maybe it's a bit more sensitive than most. I promise I'm not defending Hyundai, I've been about as fed up with it as anyone but apparently you can't treat a Hybrid like any other car.
Whether my new ICU works or not (when I get it) I will continue to leave the car on charge at every possible opportunity and see what happens.

[old man]

I'm I missing something here when cleaning the car?

I think you probably are, but it isn't purely about cleaning the car.
Your HEV has 2 batteries under the rear seats. One is a largish capacity traction battery which will propel the car periodically. The other is a small capacity Lithium battery which starts the car and runs all things electrical. When the car is switched on and the 12v battery gets low on charge, the traction battery sends a charge to top it up and when the traction battery gets low, the engine will charge it.
When you park your car and switch off the ignition, there continues to be items drawing power from the 12v battery e.g. the alarm system. Therefore, the longer the car stands unused the more chance the battery will deplete enough to cut off power to items it deems unimportant e.g. air con settings etc. If the power then drains further, you won't then be able to enter your car via the fob and you'll have to gain entry manually, press the battery reset button and then press the engine start button within 15 secs and the engine should start, after which the traction battery will send power to the 12v battery and all will be well until the next time it happens.
Worst case scenario, the 12v battery depletes so much, the battery reset button doesn't do its job and you have to call out the AA to jump start it - or do it yourself.

Now we get to the car cleaning bit. We'll assume you've parked the car for the weekend with no intention of switching on the ignition, but you intend to give the car a groom, which usually involves unlocking and opening doors and the motor driven rear hatch. All of these actions will draw power from the small capacity 12v battery and possibly deplete it enough to cause the problems I've already outlined.
You can prevent battery depletion by first opening the car and switching on the ignition. With the ignition on, the internal system will recognise when the 12v battery is getting low and top it up with a charge fron the traction battery. If the traction battery then becomes low on charge, the engine will start up on it's own and charge up the traction battery, thereby completing a continuous cycle. Therefore, when you've finished cleaning the car, you will turn off the ignition, lock the doors and the 12v battery should have virtually a full charge in it, so when you get in on Monday morning the car will start and none of the parameters you had set in the dash will have changed i.e will have reset to default.

Of course, you obviously don't want to leave the car unattended with the ignition switched on. Also, you don't need to keep your fob in a Faraday bag, as after a few minutes of inertia it will stop emitting signals that can picked up by thieves with a remote signal reader.

Forgive me if all of this is teaching you to suck eggs.

[old man]

I'm I missing something here when cleaning the car?

I think you probably are, but it isn't purely about cleaning the car.
Your HEV has 2 batteries under the rear seats. One is a largish capacity traction battery which will propel the car periodically. The other is a small capacity Lithium battery which starts the car and runs all things electrical. When the car is switched on and the 12v battery gets low on charge, the traction battery sends a charge to top it up and when the traction battery gets low, the engine will charge it.
When you park your car and switch off the ignition, there continues to be items drawing power from the 12v battery e.g. the alarm system. Therefore, the longer the car stands unused the more chance the battery will deplete enough to cut off power to items it deems unimportant e.g. air con settings etc. If the power then drains further, you won't then be able to enter your car via the fob and you'll have to gain entry manually, press the battery reset button and then press the engine start button within 15 secs and the engine should start, after which the traction battery will send power to the 12v battery and all will be well until the next time it happens.
Worst case scenario, the 12v battery depletes so much, the battery reset button doesn't do its job and you have to call out the AA to jump start it - or do it yourself.

Now we get to the car cleaning bit. We'll assume you've parked the car for the weekend with no intention of switching on the ignition, but you intend to give the car a groom, which usually involves unlocking and opening doors and the motor driven rear hatch. All of these actions will draw power from the small capacity 12v battery and possibly deplete it enough to cause the problems I've already outlined.
You can prevent battery depletion by first opening the car and switching on the ignition. With the ignition on, the internal system will recognise when the 12v battery is getting low and top it up with a charge fron the traction battery. If the traction battery then becomes low on charge, the engine will start up on it's own and charge up the traction battery, thereby completing a continuous cycle. Therefore, when you've finished cleaning the car, you will turn off the ignition, lock the doors and the 12v battery should have virtually a full charge in it, so when you get in on Monday morning the car will start and none of the parameters you had set in the dash will have changed i.e will have reset to default.

Of course, you obviously don't want to leave the car unattended with the ignition switched on. Also, you don't need to keep your fob in a Faraday bag, as after a few minutes of inertia it will stop emitting signals that can picked up by thieves with a remote signal reader.

Forgive me if all of this is teaching you to suck eggs.

And bugger !! I see now that all I just wrote was unnecessary as Terry beat me to it.

[old man]

Whether my new ICU works or not

It won't work Terry, did you see my earlier post ? Technical have been told and have escalated to the factory.

[terryp]

Whether my new ICU works or not

It won't work Terry, did you see my earlier post ? Technical have been told and have escalted to the factory.

As they say, we need to eliminate it from our enquiries.

[Southern Lad]

I'm I missing something here when cleaning the car?

I think you probably are, but it isn't purely about cleaning the car.
Your HEV has 2 batteries under the rear seats. One is a largish capacity traction battery which will propel the car periodically. The other is a small capacity Lithium battery which starts the car and runs all things electrical. When the car is switched on and the 12v battery gets low on charge, the traction battery sends a charge to top it up and when the traction battery gets low, the engine will charge it.
When you park your car and switch off the ignition, there continues to be items drawing power from the 12v battery e.g. the alarm system. Therefore, the longer the car stands unused the more chance the battery will deplete enough to cut off power to items it deems unimportant e.g. air con settings etc. If the power then drains further, you won't then be able to enter your car via the fob and you'll have to gain entry manually, press the battery reset button and then press the engine start button within 15 secs and the engine should start, after which the traction battery will send power to the 12v battery and all will be well until the next time it happens.
Worst case scenario, the 12v battery depletes so much, the battery reset button doesn't do its job and you have to call out the AA to jump start it - or do it yourself.

Now we get to the car cleaning bit. We'll assume you've parked the car for the weekend with no intention of switching on the ignition, but you intend to give the car a groom, which usually involves unlocking and opening doors and the motor driven rear hatch. All of these actions will draw power from the small capacity 12v battery and possibly deplete it enough to cause the problems I've already outlined.
You can prevent battery depletion by first opening the car and switching on the ignition. With the ignition on, the internal system will recognise when the 12v battery is getting low and top it up with a charge fron the traction battery. If the traction battery then becomes low on charge, the engine will start up on it's own and charge up the traction battery, thereby completing a continuous cycle. Therefore, when you've finished cleaning the car, you will turn off the ignition, lock the doors and the 12v battery should have virtually a full charge in it, so when you get in on Monday morning the car will start and none of the parameters you had set in the dash will have changed i.e will have reset to default.

Of course, you obviously don't want to leave the car unattended with the ignition switched on. Also, you don't need to keep your fob in a Faraday bag, as after a few minutes of inertia it will stop emitting signals that can picked up by thieves with a remote signal reader.

Forgive me if all of this is teaching you to suck eggs.

Thanks old man for that light bit of reading. As you say basically all stuff I already new but it's decent of you to go to those lengths to help out. Top marks A*

The only reason key is in a faraday pouch it's because it's one of those with a built in key chain so it's just as easy to keep it all together etc. Yes it is good that the key stops emitting a signal as you say. Because of this I have held back from adding another Immobiliser.

Back to the cleaning. If my car is unlocked while doing the cleaning the alarm won't be on so surely not using the 12v battery? But yes I understand re turning ignition on so car engine can run to stop any battery depletion. But so far I haven't done this and after several sessions each weekend of a few hours of working on the car I have not seen any battery issues like you mention doing it this way....

As was mentioned earlier though the thought of it slowly draining away while parked at the airport due to the alarm etc while on a 2 week holiday abroad isn't a good thought. Luckily if you use one of the official airport parking companies they all have a power pack jump start available in case of flat batteries.

[old man]

Thanks old man for that light bit of reading. As you say basically all stuff I already new but it's decent of you to go to those lengths to help out. Top marks A*

You're welcome, I'm retired so I have the time - mostly.
I do it for the benefit of others too, to help those that are having similar problems and also newbies to the forum that maybe have no understanding of how a HEV works.
I've no idea why you're not suffering the same faults, maybe you use the car regularly enough to keep the battery topped up. Maybe Hyundai have done some behind the scenes updates and are keeping quiet about it. I'm sure it's possible to alter software so that the threshold of the battery switching off certain settings can be raised.