[grumpy steve]

I've had an ID.3 for 6 months, and lately it has started losing charge in its 12V battery. This provokes an alarming cascade of error messages, claiming that everything from the IQ lights to the electric drive and the brakes have become faulty. Following the instructions in the manual, I have 'jump started' the car from a fume-breathing dinosaur wagon to bring the voltage up sufficiently to activate the car, and all the error messages melt away. The car then drives and operates perfectly. Until it happens again. Sometimes, low voltage on the 12V system sets of the alarm (once at 2:30am). This is, altogether getting a bit annoying.

The dealer had the car for a few days and pronounced that all systems were working correctly, the 12V battery was sound, and all software up to date (0792). When it all went wrong again a week later, (and the 12V battery was reading only 6V, while the main battery was at 80%) I called VW Assist (AKA the AA) and, after charging the 12V battery for a while, the AA technician pronounced the car fully fit.

So, what is provoking it to discharge its 12V battery? One theory I had was that the keyless entry was getting all excited because the keys were stored too close to where the car was parked. However, moving the keys and switching off keyless entry hasn't cured the problem.

My other theory is this: I have an Ohme smart charger to which I generally leave the car connected when it is in the drive. However, the charger is only enabled between 00:30 and 04:30 when electricity is cheap - the rest of the time the plug carries no power. Could this, perhaps, be confusing the car - it thinks it can call on external AC to top up the 12V battery because it is plugged in, but, most of the time, when it tries to draw power from the connector none is forthcoming?

If, as technicians keep telling me, my car is in perfect working order then the mismanagement of the 12V battery must be attributable to something I'm doing. But what?

 

[Nai3t]

Anything plugged in your OBD port?

If it's getting down to 6 volts, this sounds like something beyond a bad battery of faulty maintenance by the BMS.

I think you are chasing a phantom load, and I'm surprised the mechanics couldn't verify this. I have no idea what they could infer you are doing to cause this. My assumption is VW built a battery protection device into this car that cuts off any accessory loads of it detects the battery approaching 12 volts, do you couldn't "leave the dome light on" and run it down.

 

[Ray Noneya]

Something is not only dis charging the battery but it's not getting a charge either something is wrong !!!.

 

[grumpy steve]

Anything plugged in your OBD port?

If it's getting down to 6 volts, this sounds like something beyond a bad battery of faulty maintenance by the BMS.

I think you are chasing a phantom load, and I'm surprised the mechanics couldn't verify this. I have no idea what they could infer you are doing to cause this. My assumption is VW built a battery protection device into this car that cuts off any accessory loads of it detects the battery approaching 12 volts, do you couldn't "leave the dome light on" and run it down.

I don''t think there is anything plugged into the OBD port. I don't even know where it is. But, you're right, something must be switching itself on that draws significant power from the 12v battery. When the AA man measured the current drain with a clip on ammeter with the car switched off he found nothing. So the question is, what is switching on, and why?

 

[wanders]

I got a 1st plus with 1300km ODO in July. During the first week I three times got red and yellow triangles on the dash with drive system errors, high voltage battery errors etc.
After 2 weeks at the VW dealer they replaced a 12V wire harness and connector (description: "looks corroded" !?),
after that my ID.3 has been working fine for 1500+ km.
2.1 or 0792 software both before and after the service.

 

[grumpy steve]

I got a 1st plus with 1300km ODO in July. During the first week I three times got red and yellow triangles on the dash with drive system errors, high voltage battery errors etc.
After 2 weeks at the VW dealer they replaced a 12V wire harness and connector (description: "looks corroded" !?),
after that my ID.3 has been working fine for 1500+ km.
2.1 or 0792 software both before and after the service.

I'm very glad to hear it. My car is with the dealer at the moment. They claim it needs a new battery, despite previously claiming it was ok. I'm not confident that they have got to the underlying cause at all

 

[7S POWER]

I'm very glad to hear it. My car is with the dealer at the moment. They claim it needs a new battery, despite previously claiming it was ok. I'm not confident that they have got to the underlying cause at all

Once you get your vehicle back from the dealer, invest in one of these. You won't be sorry for having it. I do not know if it is available in the UK, but I would not be surprised that Bosch, Hella has something similar. Do not get one of those MIC junk for car and home insurance purposes. I.e. make sure it has the EU & or British Std. Approval markings. Mine is UL and CSA Approved.

7S POWER

 

[grumpy steve]

I'm very glad to hear it. My car is with the dealer at the moment. They claim it needs a new battery, despite previously claiming it was ok. I'm not confident that they have got to the underlying cause at all

I got the car back two weeks ago, and it has been fine ever since. So, perhaps it really was just a defective lead acid battery.

 

[Huey52]

You wouldn't think you'd need a new L-A battery on a new vehicle, but I had to have the 12V replaced on my wife's Benz GLA at exactly one year post delivery, so it can certainly happen. Been fine in the 2+-years since.
Conversely traded in my TTS at ~6-years on original battery. 🤷‍♂️

I got the car back two weeks ago, and it has been fine ever since. So, perhaps it really was just a defective lead acid battery.

 

[7S POWER]

That is true. It is handy to have one stored in the glove box compartment whether you need it or not. I helped a stranded motorist this morning. It was an easy peasy job. Let it charge the dead battery for 1-min., then it started the dead engine. The owner of the car was amazed at how easy it was to use it and decided to get one himself.

7S POWER

 

[Huey52]

I "rescued" my mailman a few years ago with a similar Li-ion booster, as his start/stop vehicle died right across the street from me. I told him not to shut down again until he finished his route and got back to base.
I keep one in my wife's ICE car but haven't bothered in the ID.4 since we already have a huge Li-ion booster aboard. But then I may add one for just this 'rescue others' reason.

 

[Nai3t]

... I had to have the 12V replaced on my wife's Benz GLA at exactly one year post delivery, ...

Same. My brand new i3 had a bad software load at delivery, spent a few days in the shop getting reloaded, and they changed out the 12 volt.

Only difference was it had been sitting on the showroom floor MarchAprilMayJuneJulyAugust with only 22 miles on it, so it hadn't been getting regular use, but frankly, I didn't see any of the telltale signs it was going bad, so they probably just swapped it preventatively.

I need to get one of those. I can't jump cars with my i3, and I don't think I want to with the ID.4. We have a contractor at work who provides a lot of jump starts and has been using one of those capacitor units without any issues.

 

[Huey52]

Jumper cables are soooo 20th century. These compact yet powerful Li-ion boosters are the modern way to go, and the brand/model shown above is top tier.
I've actually got an older NiCad booster in the garage (bigger/heavier). I'll start carrying that just because I have it and now have more cargo capacity. Since I recently moved my small halon extinguisher to passenger door slot I now have a cargo area abhorred vacuum ....

Same. My brand new i3 had a bad software load at delivery, spent a few days in the shop getting reloaded, and they changed out the 12 volt.

Only difference was it had been sitting on the showroom floor MarchAprilMayJuneJulyAugust with only 22 miles on it, so it hadn't been getting regular use, but frankly, I didn't see any of the telltale signs it was going bad, so they probably just swapped it preventatively.

I need to get one of those. I can't jump cars with my i3, and I don't think I want to with the ID.4. We have a contractor at work who provides a lot of jump starts and has been using one of those capacitor units without any issues.

 

[7S POWER]

Jumper cables are soooo 20th century.

What's that? Never heard it before. That must be stuff before my time

I "rescued" my mailman a few years ago with a similar Li-ion booster, as his start/stop vehicle died right across the street from me. I told him not to shut down again until he finished his route and got back to base.
I keep one in my wife's ICE car but haven't bothered in the ID.4 since we already have a huge Li-ion booster aboard. But then I may add one for just this 'rescue others' reason.

It wouldn't hurt to have one in your EV glovebox compartment. Never say never!

7S POWER

 

[Ray Noneya]

I had one of those Lio battery jumpers for a few years then the last time I used it died so now i carry a set of jumper cables in the ID.4 Yea I know I need someones battery....plenty of them around. hum a fire in the glove box....

 

[Nai3t]

I didn't realize this jump starter appearing in this thread has a battery. The one I'm referring to uses capacitors and doesn't need to be charged until used. It charges off the "dead" battery for a few minutes, then returns the favor, or can be charged quickly by another car.

 

[Ray Noneya]

I didn't realize this jump starter appearing in this thread has a battery. The one I'm referring to uses capacitors and doesn't need to be charged until used. It charges off the "dead" battery for a few minutes, then returns the favor, or can be charged quickly by another car.

Send me a link that uses capacitors......this is what i found says lithium
GB40 Boost Plus 1000A UltraSafe Lithium Jump Starter

 

[7S POWER]

I didn't realize this jump starter appearing in this thread has a battery. The one I'm referring to uses capacitors and doesn't need to be charged until used. It charges off the "dead" battery for a few minutes, then returns the favor, or can be charged quickly by another car.

Yeah, those are the MIC ones. Stay away from those junk. They aren't ULC and or CSA approved, which aren't good for the car and home insurance.

NOCO - Lithium Jump Starters

Portable lithium battery jump starter packs up to 3,000 amps. Powerful battery booster jump box for jump starting cars, boats, motorcycles and more.

no.co