Charge Control Unit Failed - Dead 12V Battery

[AndEV]

I had an incident on Sunday when the dash came up with warnings about the 12V battery voltage being low (around 11.3V initially), and telling me to pull over. I wasn’t far from home, so headed back, but the battery voltage eventually went into free fall, then the whole car died. Recovered the mile home through MG Assist (AA) - they were convinced the 12V wasn’t receiving charge from the HV battery, and it was suggested to get it to the dealership first thing in the morning. Closest (new) dealership couldn’t take it for four weeks, and the dealership I bought it from couldn’t get it in until a week on Tuesday! Battery had dropped to 8.9V in the morning (from 12.6V after recovery the night before) according to the app, and it wouldn’t start, so arranged a further recovery to the dealership, and a courtesy car through MG Assist. Courtesy car is only for 4 days, which can be extended by MG only if parts are on back-order (which I’m waiting to hear about).

Having enjoyed the car since November ‘22, this experience alone is all of a sudden starting to leave a sour taste in terms of after sales care, although I’m still hopeful that somebody will pull something out of the bag yet.

Anybody had similar experience regarding the Charge Control Unit (effectively the EV equivalent of an ICE alternator as I understand it)?

NB I used a jump pack before calling MG Assist, and things came back to life temporarily, however I was unable to release the handbrake (light on it was blinking) - same thing happened with the AA’s jump pack, however, the key to getting it released was to press and hold the handbrake button. Thought this info might prove useful to somebody.

 

[Lovemyev]

What ever the outcome now, 100% the car will require a new 12 volt battery and it looks like it will be out of warranty.
The OEM battery is only covered for 12 months.
If this is the case and you’re waiting an appointment at MG.
You could install a new battery yourself and see if it restores the car to a safe working order.
I would monitor the battery over the next couple of days, if the voltage drops wildly, disconnect it !.

 

[Ayoull]

CCU only controls the communication between the BMS, battery and charger.

What you're talking about is the DC-DC convertor, which takes 400V DC and turns it into 14V DC to charge the 12V battery.

 

[AndEV]

CCU only controls the communication between the BMS, battery and charger.

What you're talking about is the DC-DC convertor, which takes 400v DC and turns it into 14v DC to charge the 12v battery

That’s what I thought too, until the dealer stated CCU on the phone. They’re now waiting on MG approval to order the part (£1600), but because it’s available to order, MG won’t extend the courtesy car hire, which I find ridiculous! I’m glad to say that the dealer has put some effort into availing one of their cars for me, after I aired my disgust at being left stranded without a vehicle, when it’s clearly a warranty issue.

Will keep the forum posted on progress, but unlikely to be before the end of next week, with MG dragging their feet to approve the warranty claim, thereby allowing the dealer to place the order for the part.

 

[Lovemyev]

That’s what I thought too, until the dealer stated CCU on the phone. They’re now waiting on MG approval to order the part (£1600), but because it’s available to order, MG won’t extend the courtesy car hire, which I find ridiculous! I’m glad to say that the dealer has put some effort into availing one of their cars for me, after I aired my disgust at being left stranded without a vehicle, when it’s clearly a warranty issue.

Will keep the forum posted on progress, but unlikely to be before the end of next week, with MG dragging their feet to approve the warranty claim, thereby allowing the dealer to place the order for the part.

As the part is not on back order, they expect to ship the required part out to the dealer, very soon.
This is really great news, as back order parts are coming direct from China and could take a LONG time to arrive.
Keep us posted plz !.

 

[Tim Green]

How much faith do you have in the dealer - that's the question? They think it's the CCU, ( or dc/dc converter) but it could just be a faulty 12V battery, or both.
As you have not got the car, you probably have to go with whatever the dealer says.
But there has been a lot on the forum about faulty 12V batteries.

 

[Coulomb]

Well, the CCU has to tell the DC-DC when to turn on and how much current and what voltage limit. And there seems to have been a spate of faulty CCUs, causing other problems like failed charging. So much so that MG UK is arranging for a shipment of CCUs (I read in another thread).

It seems that they are a non-SAIC part, and it seems that the manufacturer is having trouble keeping up with demand (I wonder why?). So it still may take some time to arrive.

It seems like it would be a pretty simple part: just an automotive spec computer with a CAN bus port. And of course firmware, but this doesn't seem to be a firmware issue. Strange that they are having these problems.

Edit: And £1600 seems over the top for that little thing. It looks like something you could get from a hobby shop for £100, double it for automotive specs, add 50% markup for warehousing etc and that comes to £300. But what do I know.

 

[Tim Green]

Well the name Charge Control Unit implies that it does more than just look after a DC-DC converter, which at probably about 100W is no big deal. Maybe it looks after both batteries and their charging regimes? And the cost implies some heavy duty electronics so maybe some of the main ac/dc charging of the main battery?

 

[AndEV]

Pretty sure it’s not just a 12V battery issue (although I’d imagine that it will be shot now), as the AA guy checked the voltage across the terminals with the car in ready mode, and it didn’t increase, implying that it was not charging from the HV battery.

As for faith in the dealer, the jury’s out at the moment - we’ll see how the situation pans out!

Interesting to hear that there has been a spate of problems with CCU’s, as I couldn’t find anything when I searched the forum before starting this thread.

 

[Coulomb]

implies that it does more than just look after a DC-DC converter, which at probably about 100W is no big deal.

? I don't follow. The DC-DC in a typical EV is well over 1000 W; it has to be able to run all the 12 V loads and also charge the auxiliary battery.

My understanding is that the CCU doesn't do anything powerful itself, it just sends CAN bus messages to the muscle ECUs (the DC-DC and the On Board Charger), listening to information from the Battery Management Unit and other things.

Edit: In other words, it's brain, not brawn.

 

[AndEV]

Had it confirmed that the parts required are a new CCU and a new 12V battery. Dealer still waiting on MG approval to proceed.

 

[Lovemyev]

Hopefully they are not on back order from China.
If they are, they should get a loan car.

 

[AndEV]

Hopefully they are not on back order from China.
If they are, they should get a loan car.

They’ve managed to shuffle things around and give me a loaner (HS auto) until Tuesday, when they need it back, but hopefully they’ll be able to shuffle things again to put me in something else until my ZS is fixed.

 

[Tim Green]

Of course you are right, I was forgetting they use 12V to run the usual car systems...
However, I still think £1600 is a lot for brain not brawn but it's a long time since I worked in electronics at Smiths Industries....

 

[Lovemyev]

Of course you are right, I was forgetting they use 12v to run the usual car systems...
However, I still think £1600 is a lot for brain not brawn but it's a long time since I worked in electronics at Smiths Industries....

My neighbour needed the gateway module and 12 volt battery replacing on his 21 reg Audi Q5 just before Xmas.
He was doing a skip run and filled the boot and the back of the car with black bin bags.
One of the bags leaked on route and liquid went through the seat base.
It penetrated the module, and shorted it out.
This then rendered all of the modules in the car useless.
Car was recovered to the main dealers ( who had taken in 30 other recovered cars on the same day ) and they had it for about two weeks.
Neither Audi or the lease company would pick up the bill of £1,500.
Expensive tip run !.
Oh ……. Just to rub salt into the wound, the lease runs out in March of this year .

 

[Coulomb]

Interesting to hear that there has been a spate of problems with CCU’s, as I couldn’t find anything when I searched the forum before starting this thread.

I finally found it in the MG4 forum:

Zappi failing to charge car to 80% (Edit update: Not a problem with Zappi. Issue with AC charging/New CCU ordered)

this is the internal configuration of a 3ph OBC That looks more like the configuration for a 3-phase motor controller, with the HV battery stuck on at the right hand end. In the "single phase" diagram, you appear to be connecting to two phases, not to active (one phase) and neutral. My guess...

www.mgevs.com

Perhaps there was mention of it in a recent podcast.