V2L warning - also discharges 12v battery!

[inneseaton]

So first time using our new V2L cable on the campsite last night and awoke to a flat 12v battery.

It seems that with the V2L cable attached there is some form of drain on the 12v battery although I cannot work out what or why?!

The process we followed was:

• car on, discharge screen set to 40% minimum and start discharging
• car off and locked

Vehicle is a facelift ZS EV Trophy long range registered at the end of May.

Overnight we consumed about 1kwh of mains power (HV battery dropped by 1%) but 12v battery was reading 5.5v this morning.

AA had to be called as we had no way of jump starting but they did it successfully.

If this is a thing then it makes the V2L useless. Any ideas on why it would touch the 12v and how to stop it?

 

[Kithmo]

Looks like you may have to have the car on to use it, as you say, a bit useless.
I thought the new ZS monitored the 12v and kept it maintained via the HV, maybe there's a setting for that ?

 

[stevenc152]

So first time using our new V2L cable on the campsite last night and awoke to a flat 12v battery.

It seems that with the V2L cable attached there is some form of drain on the 12v battery although I cannot work out what or why?!

The process we followed was:

• car on, discharge screen set to 40% minimum and start discharging
• car off and locked

Vehicle is a facelift ZS EV Trophy long range registered at the end of May.

Overnight we consumed about 1kwh of mains power (HV battery dropped by 1%) but 12v battery was reading 5.5v this morning.

AA had to be called as we had no way of jump starting but they did it successfully.

If this is a thing then it makes the V2L useless. Any ideas on why it would touch the 12v and how to stop it?

So what ive worked out is this
1) if your 12v goes under 12 the computer locks a fault code in, the battery will not recharge on a charger or start
2) if you have said error, the cars bricked.
3) If you run the 12v down for any reason what so ever it dies.


The car needs a serious overall in terms of power management.

 

[Coulomb]

I'm surprised. To run the charger backwards, the contactors have to be on, so that's a drain on the 12 V system. But I thought that any time that the contactors were on, the DC-DC would be running, keeping the 12 V battery topped up at 13.x volts, or at times actively charging it at 14.x volts.

It would be good to see what the 12 V battery voltage is during a V2L session.

The following seems possible, though unlikely. Some 12 V batteries seem to have had a hard time while waiting for parts in a holding yard in China, possibly for months. This explains the relatively high incidence of 12 V battery failures of late. Perhaps your 12 V battery was one of those, and just happened to collapse the night it was running V2L.

As I type this, it seems even less plausible.

The good news is that presumably, this could all be corrected by an over-the-air update. Or at least, I can't think of a reason why it could not. And with the lightning speed that MG firmware bugs get corrected ...

 

[stevenc152]

The good news is that presumably, this could all be corrected by an over-the-air update. Or at least, I can't think of a reason why it could not. And with the lightning speed that MG firmware bugs get corrected ...

Already been said over the air updates are info only, nothing for the car, back to the garage you go.

 

[inneseaton]

Looks like you may have to have the car on to use it, as you say, a bit useless.
I thought the new ZS monitored the 12v and kept it maintained via the HV, maybe there's a setting for that ?

You are correct - it does usually keep the 12v battery topped up but for some reason it all went wrong with the V2L connected!

 

[inneseaton]

I'm surprised. To run the charger backwards, the contactors have to be on, so that's a drain on the 12 V system. But I thought that any time that the contactors were on, the DC-DC would be running, keeping the 12 V battery topped up at 13.x volts, or at times actively charging it at 14.x volts.

It would be good to see what the 12 V battery voltage is during a V2L session.

The following seems possible, though unlikely. Some 12 V batteries seem to have had a hard time while waiting for parts in a holding yard in China, possibly for months. This explains the relatively high incidence of 12 V battery failures of late. Perhaps your 12 V battery was one of those, and just happened to collapse the night it was running V2L.

As I type this, it seems even less plausible.

The good news is that presumably, this could all be corrected by an over-the-air update. Or at least, I can't think of a reason why it could not. And with the lightning speed that MG firmware bugs get corrected ...

Thank you - yes we did consider whether the 12v just decided now was the time to fail, although that would be some coincidence!

The vehicle is sitting on a charger as we speak - when we get back I will check the voltages during discharge and see whether that gives any clues.

To be continued….

 

[MAJ]

The following seems possible, though unlikely. Some 12 V batteries seem to have had a hard time while waiting for parts in a holding yard in China, possibly for months. This explains the relatively high incidence of 12 V battery failures of late. Perhaps your 12 V battery was one of those, and just happened to collapse the night it was running V2L.

I think the above could be correct, if any 12volt Lead Acid battery is allowed to stand for a long period in a discharged state (ie under 10volts) perminent damage will result.
Because on an EV the 12volt battery is only used to boot up the system very little power is required, and if the car is used regularly, it will have sufficient power even in this damaged state to do its job.
Any small drain on the 12volt system could cause the voltage to drop quickly to below 10volts. in this case the voltage was down to 5.5volts (Totally Knackered).
I would suggest anyone experiencing issues of this kind should have the battery Load Tested, and not just recharged.

 

[inneseaton]

I think the above could be correct, if any 12volt Lead Acid battery is allowed to stand for a long period in a discharged state (ie under 10volts) perminent damage will result.
Because on an EV the 12volt battery is only used to boot up the system very little power is required, and if the car is used regularly, it will have sufficient power even in this damaged state to do its job.
Any small drain on the 12volt system could cause the voltage to drop quickly to below 10volts. in this case the voltage was down to 5.5volts (Totally Knackered).
I would suggest anyone experiencing issues of this kind should have the battery Load Tested, and not just recharged.

Thank you and noted - I shall pop in to the local dealer tomorrow and get it properly tested.

So far from my experimentation this afternoon, the voltage is wandering between 13.2 and 13.6 volts with the V2L attached, with a 100w load. Interestingly, the app is telling me that my battery voltage is 14.3v! Whether there is a voltage sensing issue that is contributing? The car is powered off and there doesn’t seem to be any difference locked vs unlocked.

if it holds as it is then it shouldn’t discharge in theory - time will tell!

 

[inneseaton]

On another note - I purchased a plug in tester today and it says the polarity is reversed on the supply from the V2L. Having heard of this issue on French campsites, my impression is that this isn’t a cause for concern? Or is it?!

 

[stevenc152]

On another note - I purchased a plug in tester today and it says the polarity is reversed on the supply from the V2L. Having heard of this issue on French campsites, my impression is that this isn’t a cause for concern? Or is it?!

Whole cars cause for concern..

 

[MAJ]

On another note - I purchased a plug in tester today and it says the polarity is reversed on the supply from the V2L. Having heard of this issue on French campsites, my impression is that this isn’t a cause for concern? Or is it?!

Polarity shouldn't be a major problem, but be aware this will not supply a pure sine wave, this can cause issues with some electronic devices.

 

[inneseaton]

Polarity shouldn't be a major problem, but be aware this will not supply a pure sine wave, this can cause issues with some electronic devices.

Thanks - that mirrors the advice we had with the caravan in France. W

 

[hmadsen]

Polarity shouldn't be a major problem, but be aware this will not supply a pure sine wave, this can cause issues with some electronic devices.

Most electronic devices have a SMPS built in, the first component the "AC" hits when entering such an electronic device is a bridge rectifier, and a big fat capacitor, effectively making any kind of wave, sine, square or stepped into a DC voltage, that it will then itself chop up into a "higher" frequency (usually KHz) and then feed it into a transformer, and step it down, and then rectify and smooth out to whatever voltage is needed internally.

Old clock radio's used the frequency for generating the clock signal, so such a device might get confused and go a lot faster, but other than that, i don't see what other devices would be affected.

 

[inneseaton]

Most electronic devices have a SMPS built in, the first component the "AC" hits when entering such an electronic device is a bridge rectifier, and a big fat capacitor, effectively making any kind of wave, sine, square or stepped into a DC voltage, that it will then itself chop up into a "higher" frequency (usually KHz) and then feed it into a transformer, and step it down, and then rectify and smooth out to whatever voltage is needed internally.

Old clock radio's used the frequency for generating the clock signal, so such a device might get confused and go a lot faster, but other than that, i don't see what other devices would be affected.

That’s useful to know and definitely reassuring!

Of interest so far then is that the Jackery mains charger only works for about 10 minutes when plugged in to the V2L supply (it works fine at home) and my other half’s electric blanket keeps resetting itself at random to the lowest setting (again, has never happened at home).

There do seem to be some teething problems at least!

 

[Coulomb]

I purchased a plug in tester today and it says the polarity is reversed on the supply from the V2L.

If you mean that active and neutral are reversed, that's possibly because the car doesn't have a proper earth. If so, that's more or less to be expected.

the voltage is wandering between 13.2 and 13.6 volts with the V2L attached, with a 100w load. Interestingly, the app is telling me that my battery voltage is 14.3v!

Something is wrong there. I think that the bad measurement is likely the cause. If that night it thought that 11.5V was really 14.3V, then it would think that there is no need to charge the auxiliary battery, so it would have run flat just running computers, fans, display, contactors, and the electronics in the on-board charger.

Looks like you need a replacement ECU, whichever one measures the auxiliary battery. That will cost SAIC a pretty penny. If they did board level repair, the parts would likely come to less than one pound. Plus a lot of labour, of course.

If they let you keep the original ECU, I'll pay packing and shipping to Australia. I'm pretty sure I can fix it, and learn a bit from inspection.

There is a small chance that it's an intermittent or faulty sense wire or fuse in that sense wire.

 

[Ozzie1989]

On another note - I purchased a plug in tester today and it says the polarity is reversed on the supply from the V2L. Having heard of this issue on French campsites, my impression is that this isn’t a cause for concern? Or is it?!

Whilst this won't affect many household items likely to be used for camping, personally I would swap the active and neutral conductors in the plug to prevent any future issues (especially if used with sensitive household items during a power cut for example).

As for your 12v battery, leave the V2L connected with a load for a few hours to check the DC charger doesn't disconnect after a period of time.

 

[inneseaton]

If you mean that active and neutral are reversed, that's possibly because the car doesn't have a proper earth. If so, that's more or less to be expected.


Something is wrong there. I think that the bad measurement is likely the cause. If that night it thought that 11.5V was really 14.3V, then it would think that there is no need to charge the auxiliary battery, so it would have run flat just running computers, fans, display, contactors, and the electronics in the on-board charger.

Looks like you need a replacement ECU, whichever one measures the auxiliary battery. That will cost SAIC a pretty penny. If they did board level repair, the parts would likely come to less than one pound. Plus a lot of labour, of course.

If they let you keep the original ECU, I'll pay packing and shipping to Australia. I'm pretty sure I can fix it, and learn a bit from inspection.

There is a small chance that it's an intermittent or faulty sense wire or fuse in that sense wire.

Great info thank you - I certainly will. I looked a bit more into the voltage readouts and it does seem that the drivers display is correct, the app seems to have a lag in it.

 

[inneseaton]

Whilst this won't affect many household items likely to be used for camping, personally I would swap the active and neutral conductors in the plug to prevent any future issues (especially if used with sensitive household items during a power cut for example).

As for your 12v battery, leave the V2L connected with a load for a few hours to check the DC charger doesn't disconnect after a period of time.

Yes I am thinking to do that as a permanent fix for when camping.

Also, yes, the 12v charger does seem to cut out at some point, as we awoke with a flat battery again.

 

[hmadsen]

That’s useful to know and definitely reassuring!

Of interest so far then is that the Jackery mains charger only works for about 10 minutes when plugged in to the V2L supply (it works fine at home) and my other half’s electric blanket keeps resetting itself at random to the lowest setting (again, has never happened at home).

There do seem to be some teething problems at least!

Well an electric blanket will most likely be just a resistive heating "pad" and i would not expect the circuitry in such an appliance to be very sophisticated, so it might be affected.

The Jackery charger is not something i know what is, or what is for.

Would be interesting if someone with an oscilloscope and a V2L adaptor, would take some pictures of the "sinewave" that is produced by the car.