Mg 5 inverter (on board charger)

[violeta]

Hi there unfortunately my car has been off the road due to problem with DC inverter, part itself cost 2100 £ but I have to wait a month till gets fitted by MG , I have found a used one and a mechanic ready to carry out the job but not sure it will need a software update or the car will be ready to be driven.

 

[shpub]

There are plenty of inverters on ebay so I would make sure that the s/h one you have is the same build and version number as the one in your car. That then gives you a reasonable chance that the software is the same and therefore less likely to have problems. As for will it be a plug and go? I don't know because there may be software revisions issues - hence get a matching one - or even hardware differences. There may well be VIN locking where the units only work with a particular car although there was a youtube video of someone swapping out a MG traction battery and it just worked.

The problem is nobody really knows for definite.

I would also make sure that the mechanic is qualified to work on EVs as the car would need to go through a manual disconnect procedure to isolate the 400v battery which is connected to the unit. It is not an unplug and plug back in as it is possible to cause sparks, damage bits or yourself unless the right procedure is followed. If he or she doesn't know about this stuff, I would not take the risk.

 

[Verdigris]

I'm not sure if the inverter unit will be coded to the car, although some electronic components are, so a bit more research would be wise, before you part with your cash.

 

[Alb]

The CCU is coded to the car.

 

[Coulomb]

I presume that "DC inverter" is actually the DC-DC converter, which charges the auxiliary (12V) battery from the main (400V) battery.

It is part of the Combined Charging Unit (hope I got that right), or CCU.

It's possible that coding the VIN into the CCU will require special tools that only official MG dealers have access to, and MG dealers may refuse to code it if they didn't install a new MG CCU. I hate the concept of VIN locking, it smacks of anti-competitive behaviour.

But some third party mechanics pay a subscription to fancy scanners that pride themselves on being able to do such things. Good luck.

 

[MickeySw]

I would also make sure that the mechanic is qualified to work on EVs as the car would need to go through a manual disconnect procedure to isolate the 400v battery which is connected to the unit. It is not an unplug and plug back in as it is possible to cause sparks, damage bits or yourself unless the right procedure is followed. If he or she doesn't know about this stuff, I would not take the risk.

It’s always advisable to get professionals to do a job but generally speaking when an EV is turned off, the HV battery is separated from the rest of the car, disconnecting the 12V aux will keep the contactors shut and for extra safety there is a manual HV service disconnect plug.

I presume that "DC inverter" is actually the DC-DC converter, which charges the auxiliary (12V) battery from the main (400V) battery.

It is part of the Combined Charging Unit (hope I got that right), or CCU.

Looks like MG refers to the CCU as inverter according to pic below:

 

[shpub]

It’s always advisable to get professionals to do a job but generally speaking when an EV is turned off, the HV battery is separated from the rest of the car, disconnecting the 12V aux will keep the contactors shut and for extra safety there is a manual HV service disconnect plug.

All that is true and there is also an HVIL circuit that will disconnect the battery if a cable is pulled out. All that should be done and the ignition keys locked away several metres from the car to prevent accidental switch on.

When I did my EV training, we were told not to rely on any of this because there are capacitors that still remain charged at 400v and it is not unknown for contactors to weld shut so that the battery remains connected. This is why the procedure manuals say wait for 5 mins between stages. As part of the training we actually measured how long it took to discharge some units and there was still a sizeable voltage after that time period. Again a good reason to measure and check. The phrase frequently used was " do you feel lucky? and "should" are not acceptable risk assessments!".

The overwhelming mantra was wear the appropriate PPE, check everything and assume nothing.

It appears to be overkill at first but considering the voltages are lethal, I still check even when I hear the contactor clunk! Its clunked but has it clunked open or clunked closed....

I presume that "DC inverter" is actually the DC-DC converter, which charges the auxiliary (12V) battery from the main (400V) battery.

It is part of the Combined Charging Unit (hope I got that right), or CCU.

It's possible that coding the VIN into the CCU will require special tools that only official MG dealers have access to, and MG dealers may refuse to code it if they didn't install a new MG CCU. I hate the concept of VIN locking, it smacks of anti-competitive behaviour.

But some third party mechanics pay a subscription to fancy scanners that pride themselves on being able to do such things. Good luck.

I believe it is also programmed with the battery chemistry charging details - so MG don't want a unit for a SR to charge a LR and vice versa.

 

[Gomev]

Hi there unfortunately my car has been off the road due to problem with DC inverter, part itself cost 2100 £ but I have to wait a month till gets fitted by MG , I have found a used one and a mechanic ready to carry out the job but not sure it will need a software update or the car will be ready to be driven.

Why isn't this being fixed under warranty ?

 

[MickeySw]

I believe it is also programmed with the battery chemistry charging details - so MG don't want a unit for a SR to charge a LR and vice versa.

I thought that the BMS is ’central command’ when it comes to all HV battery related functions?

 

[Coulomb]

Looks like MG refers to the CCU as inverter according to pic below:

Ah! Thanks for pointing that out.

That's so confusing as an inverter is by definition something that turns DC into AC; the "wrong way around" as DC is used for nearly everything (except electricity distribution, where it's extremely useful). So the CCU's primary job is the complete opposite: it converts AC to DC; this is termed a rectifier (as now the power conversion is in the "right" direction; the wrong has been rectified, if you like).

When a CCU is operated in reverse for V2L, then indeed it is an inverter; maybe that's a special term for CCUs that have the V2L capability.

All modern EVs do have one conspicuous inverter: the motor controller. This converts DC into three phase AC to drive the motor. So when people talk about inverters in an EV, I immediately think of the motor controller.

 

[Verdigris]

Isn't the the traction motor is AC, so will require an inverter to convert the battery power to AC?

 

[shpub]

I thought that the BMS is ’central command’ when it comes to all HV battery related functions?

It has a veto certainly but it reports cell volts and temps to other units like the evcc which know what is going on re charging and driving. It is part of the decision making in the car. The BMS knows nothing about the charging side so can't make decisions without the bits of information associated with that. It can say shutdown in emergency, but it normally just reports just the battery conditions for others to decide what to do. As long as the battery is in the happy zone it doesn't really care and just sends out the data. Go out of that and the veto gets applied PDQ.

Isn't the the traction motor is AC, so will require an inverter to convert the battery power to AC?

Yes. However depending on your background that box of tricks is often referred to as a motor controller, drive, inverter or even converter. Confusing it definitely is. Then you get different manufacturers using different names. The BMW EVCC equivalent is called... a LIM! The Tesla AC charger is called a charger even though it is reality just an inverter and doesn't have the charging functions that would be expected in a true charger. There is little consistency.

 

[MickeySw]

It has a veto certainly but it reports cell volts and temps to other units like the evcc which know what is going on re charging and driving. It is part of the decision making in the car. The BMS knows nothing about the charging side so can't make decisions without the bits of information associated with that. It can say shutdown in emergency, but it normally just reports just the battery conditions for others to decide what to do. As long as the battery is in the happy zone it doesn't really care and just sends out the data. Go out of that and the veto gets applied PDQ.

You have to give the BMS a bit more credit than above, after all the ‘M’ stands for ‘Management’ ?
It also determines SoH, SoC and is in charge of balancing. In order to do that it needs to know the capacity and charge/discharge characteristics of the relevant battery chemistry.

The CCU on the other side is more likely to ‘just follow instructions’

 

[shpub]

You have to give the BMS a bit more credit than above, after all the ‘M’ stands for ‘Management’ ?
It also determines SoH, SoC and is in charge of balancing. In order to do that it needs to know the capacity and charge/discharge characteristics of the relevant battery chemistry.

The CCU on the other side is more likely to ‘just follow instructions’

Yes I'll raise it to an assistant manager then I probably did over simplify things a bit.

The CCU module can be programmed with different charging strategies like constant current/constant voltage switch over point, voltage and current ramping and so on etc, so is linked to the battery chemistry in that way and the rest of the car's system.

It certainly doesn't understand the battery chemistry like the BMS and if I inferred that it was the only repository of that information then I apologise.

 

[Coulomb]

The CCU module can be programmed with different charging strategies like constant current/constant voltage switch over point, voltage and current ramping and so on etc, so is linked to the battery chemistry in that way and the rest of the car's system.

I would think that the CCU just takes voltage and current limits off the CAN bus from either the BMS or the EV-ECU (probably the wrong name). That way, the same ECU can work with either battery chemistry. One less module that has to be matched to the battery type.

 

[phantom]

Hello every one just read all your post
I'm in near the end of converting my toyota estima hybrid to all electric I have uesd a mg5ev ex.
To do this all is working only one problem the ccu has been changed on the mg5 ev and I have a different vin number in it as all the components on the mg have the vin number in the it's not talking to the bms is there any way of checking the ccu or changing the vin to match the rest of the car
Thanks D

 

[Coulomb]

is there any way of checking the ccu or changing the vin to match the rest of the car

That's going to take some advanced hacking, I think.

Are you saying that you have a matched set of ECUs except for the CCU (on-board charger and DC-DC converter)? And this mismatch is causing a problem?

I would have hoped that the CCU would be one of the ECUs that didn't care about VINs. The Mitsubishi iMiEV on-board charger is not VIN sensitive, for example.

 

[shpub]

I would have hoped that the CCU would be one of the ECUs that didn't care about VINs. The Mitsubishi iMiEV on-board charger is not VIN sensitive, for example.

There are multiple versions of that CCU and they vary in terms of the power and voltage outputs and also include V2L capability. No you can't get a newer unit and retrofit to get V2L. It would make sense to "vin lock" them so that the wrong unit does not go and do some thing silly like charging a 450v battery with a 400v charger.

 

[MickeySw]

To do this all is working only one problem the ccu has been changed on the mg5 ev and I have a different vin number

How can all be working when the CCU isn’t?
What components did you use from the donor MG5?
Was the CCU already faulty on the MG5 and you’re trying to replace it with a new one?

 

[phantom]

How can all be working when the CCU isn’t?
What components did you use from the donor MG5?
Was the CCU already faulty on the MG5 and you’re trying to replace it with a new one?

Hi thank for your response I bought a mg5 ev that was rear ended when it was parked so all components should have been OK but the person that I bought it from was changed the ccu may be because then had an mg that has a faulty one I don't know its to late for me to go back to him as my project has taken me nearly 2 years to do
I have bought a Diagnostic machine that can read and up date all the ecus and it has told me that the ccu ecu is not for this car

That's going to take some advanced hacking, I think.

Are you saying that you have a matched set of ECUs except for the CCU (on-board charger and DC-DC converter)? And this mismatch is causing a problem?

I would have hoped that the CCU would be one of the ECUs that didn't care about VINs. The Mitsubishi iMiEV on-board charger is not VIN sensitive, for example.

Hi yes

How can all be working when the CCU isn’t?
What components did you use from the donor MG5?
Was the CCU already faulty on the MG5 and you’re trying to replace it with a new one?

Hi yes it must have been faulty