No ignition or any 12V power.

[craig Dandeaux]

I have left the car on charger, unlocked for 6 weeks, while on holiday. Came back and nothing works, no ignition, windows, wipers, lights.
The charger light had power and the green light was flashing.
Volt meter on 12V battery was 10V. Had it on a 12V 4 amp charger overnight but still no electrical response. The car is 2 years old so the 12V battery should be fine.
Anyone had any experience like this?

 

[Bam Bam]

I have left the car on charger, unlocked for 6 weeks, while on holiday. Came back and nothing works, no ignition, windows, wipers, lights.
The charger light had power and the green light was flashing.
Volt meter on 12v battery was 10v. Had it on a 12v 4 amp charger overnight but still no electrical response. The car is 2years old so the 12v battery should be fine.
Anyone had any experience like this?

You mean the 12V was on a charger?

Or was the EV itself plugged in via type 2?

I would have thought the 12V battery wouldn't get topped up if the car itself was plugged in.

I did have a previous ICE car with an electrical issue that chewed through batteries. Sometimes they go bad even after a short lifespan if they are run down.

In the UK the roadside assistant firms have a device they can plug in to a 12V battery and assess if it is damaged beyond salvageability.

 

[Coulomb]

I had something similar with my MG4, but fortunately while on the driveway. I had left the cgarge lead plugged in, not charging, for a day or two. The 22V battery was down to about 3.5V. With my 6A 12V charger hooked up to the car, it soon got to about 8V, but then the car elecctronics kicked in and overwhelmed the 6A charger, causing the car to start and stop with about a 1.5 second cycle. Fortunately I was there to see this and stopped the charge.

I then disconned the negative lead from the battery, and restarted the charge with the battery on its own. I left that overnight. Next day, the 12V battery seemed fine, and the car restarted fine when reconnected. I watched the 22V battery voltage carefully for a few days, and it seems ok. I suspect that I've lost a few weeks of its life though. I was lucky that the 13V battery didn't stay highly discharged for more than half a day or so. This was weeks ago and I've had no problems since.

In your case, 10V sounds like a cell may have collapsed to zero volts (five two volt cells is about 10V), and cells usually don't come back from that. But it's probably worth trying to charge the battery disconnected from the car. If it went dead flat near the end of its 6 weeks of inactivity, it may last another year or so.

Edit: Perhaps leaving it unlocked long term was the problem. The car may leave computers running, or at least not fully sleeping, until locked doors signals that it's time to go into low power mode.

 

[craig Dandeaux]

You mean the 12V was on a charger?

Or was the EV itself plugged in via type 2?

I would have thought the 12V battery wouldn't get topped up if the car itself was plugged in.

I did have a previous ICE car with an electrical issue that chewed through batteries. Sometimes they go bad even after a short lifespan if they are run down.

In the UK the roadside assistant firms have a device they can plug in to a 12V battery and assess if it is damaged beyond salvageability.

I am new to the site and having some difficulties replying but all fixed now.

The car drive battery was on charge and is at 80%. The 12V systems battery was not on charge but I assumed it would be charged as part of the drive battery charging. I have since bypassed the 12V systems battery and used a spare one which gets all the systems up and running.
Looks like something has gone wrong with the 12V charging software or the battery has just crashed.
Thank you for your very prompt advice.

I had something similar with my MG4, but fortunately while on the driveway. I had left the cgarge lead plugged in, not charging, for a day or two. The 22V battery was down to about 3.5V. With my 6A 12V charger hooked up to the car, it soon got to about 8V, but then the car elecctronics kicked in and overwhelmed the 6A charger, causing the car to start and stop with about a 1.5 second cycle. Fortunately I was there to see this and stopped the charge.

I then disconned the negative lead from the battery, and restarted the charge with the battery on its own. I left that overnight. Next day, the 12V battery seemed fine, and the car restarted fine when reconnected. I watched the 22V battery voltage carefully for a few days, and it seems ok. I suspect that I've lost a few weeks of its life though. I was lucky that the 13V battery didn't stay highly discharged for more than half a day or so. This was weeks ago and I've had no problems since.

In your case, 10V sounds like a cell may have collapsed to zero volts (five two volt cells is about 10V), and cells usually don't come back from that. But it's probably worth trying to charge the battery disconnected from the car. If it went dead flat near the end of its 6 weeks of inactivity, it may last another year or so.

Edit: Perhaps leaving it unlocked long term was the problem. The car may leave computers running, or at least not fully sleeping, until locked doors signals that it's time to go into low power mode.

Thank you for your advice.
I didn’t appreciate that even when turned off systems would be running in the back ground. I will lock it in future. It would appear to be the problem as a spare battery seems to start all the systems.
I have a 2012 Nissan ENV200 van which seems far more reliable than the MG I have a feeling it is all the extra computer management is causing a lot of issues.
I also have a mini moke no computer problems there!

 

[Coulomb]

I assumed it would be charged as part of the drive battery charging.

That certainly happens on my MG4 and ZS EV. But after the main battery reaches the set SoC point, I'm not sure. The main charge stops, so I assume that the 12V stops being floated (the 12V battery having stopped actual charging at 14+ volts long ago). So then it's in the same situation as my MG4 was: plugged in but not charging. It seems that some MG firmware "forgets" to look after the 12V battery in this situation. People have reported leaving their MGs unattended for 6 weeks or more with no issue, so perhaps if you had not plugged the car in at all, it would have been fine.

 

[craig Dandeaux]

That certainly happens on my MG4 and ZS EV. But after the main battery reaches the set SoC point, I'm not sure. The main charge stops, so I assume that the 12V stops being floated (the 12V battery having stopped actual charging at 14+ volts long ago). So then it's in the same situation as my MG4 was: plugged in but not charging. It seems that some MG firmware "forgets" to look after the 12V battery in this situation. People have reported leaving their MGs unattended for 6 weeks or more with no issue, so perhaps if you had not plugged the car in at all, it would have been fine.

I need to experiment with how I leave it. All part of the learning process.

 

[T1 Terry]

If you plan to leave a 12v battery connected to anything, 4 weeks seems to be about the limit without a maintenance charger connected across the 12v battery. Sometimes they will sit for 2 mths, but not always, so, the 12v maintenance charger is the go if the vehicle is to be left connected for an extended period.

The deeply discharged 12v battery might come good if connected to a charger with a recondition or de-sulphate cycle, but it will take a week at least.

I was recharging my house battery in the motorhome using jumper leads from the MG4 ..... as long as the car was in ready mode, all was fine, the MG4 DC to DC would keep the 12v battery at 14.2v, but the MG4 would shut off after .... I don't really know how long, maybe a few hrs, the MG4 12v battery discharged until the two batteries were close to the same voltage ..... set the MG4 in ready mode again, and it would return to charging at 60 amps ..... until it replaced all 600Ah @ 14vdc. It used roughly 11% SOC out of the 51's drive battery ....

I haven't had to repeat the MG4 recharger trick since, but I was going to try a weight on the drivers seat and see if that would keep it in ready mode.

T1 Terry

 

[craig Dandeaux]

If you plan to leave a 12v battery connected to anything, 4 weeks seems to be about the limit without a maintenance charger connected across the 12v battery. Sometimes they will sit for 2 mths, but not always, so, the 12v maintenance charger is the go if the vehicle is to be left connected for an extended period.

The deeply discharged 12v battery might come good if connected to a charger with a recondition or de-sulphate cycle, but it will take a week at least.

I was recharging my house battery in the motorhome using jumper leads from the MG4 ..... as long as the car was in ready mode, all was fine, the MG4 DC to DC would keep the 12v battery at 14.2v, but the MG4 would shut off after .... I don't really know how long, maybe a few hrs, the MG4 12v battery discharged until the two batteries were close to the same voltage ..... set the MG4 in ready mode again, and it would return to charging at 60 amps ..... until it replaced all 600Ah @ 14vdc. It used roughly 11% SOC out of the 51's drive battery ....

I haven't had to repeat the MG4 recharger trick since, but I was going to try a weight on the drivers seat and see if that would keep it in ready mode.

T1 Terry

Thanks for this Terry. I think my issue is much smaller than what you have uncovered but with every post I am seeing how innovative owners can be.