AC charging rate

[Mgkev]

Hi, can someone tell me what the fastest AC charging rate that is achievable with the ZS?
I ask because I read recently on this forum that it is only 7Kw and if so any rapid charging would only be possible with DC chargers.
Many thanks, Kev.

 

[JMX]

I get about 7.2kw which is about the max the onboard charger will support.

 

[Mgkev]

It’s strange because I’ve read the manual front to back again today ayI can’t find any charge rates detailed except max times from empty.

 

[Mark Holmes]

I believe there are two charging modules in the ZS EV one being a 7 kWh unit and the other the CSS unit that can allegedly go above 50 kWh, but just how much more I’m not sure.

 

[Mgkev]

So really only DC rapid chargers are useful. 22Kw , 44Kw etc AC charging is a waste of time then ?

 

[Mark Holmes]

Yes from what I’ve been told unless another member of this forum is going to tell me what I’ve said is incorrect!!

 

[Frank]

Dear All,

Yes when charging AC the input goes via the onboard charger which will ONLY accept "up to 7Kw which is ok for overnight charging. For ANY distances over the range of the car the only feasible way to charge the car is using RAPID charges (a lot of people on this forum keep using the term FAST when they are talking about DC chargers, they are not FAST they are RAPID). For those new to the game there are 3 different speeds of charging: Slow (up to 3kw only suitable for 12+ hours charging), Fast (up to 7Kw, usual home charger output and good for charging overnight), and then anything over 7Kw is classified as a RAPID charger which is usually DC but they are some AC chargers with can charge up to 47Kw, which are RAPID but no good to us.

Anyway back to the answer due to the on board charger only accepting up to 7Kw the ONLY way to charge on long trips is to use DC and the CCS (Combined Charging System) which bypasses the car's on board charger hence why the car can charge up to 80Kw (but tests show it only achieves these speed very rarely. Usually sits around about 45Kw and slows down to 20Kw when over or just approaching 80% charge.

So unless you have a spare 8 hours or so when travelling only use RAPID DC chargers unless you are staying overnight at a Hotel and use their 7Kw chargers to charge overnight (when booking a Hotel now I ALWAYS use a Hotel with EV Charging).

Frank

PS If you come up to a charger that has a mixture of outputs with DC CCS and the Leafs DC cable cdaemo or something and a vehicle is using the DC cdaemo (wrong term but something like that) then unfortunately I have found that you will NOT be able to use the DC CCS because the charger can't handle them both being on at the same time. This sucks in my opinion but EVERY charger I have came across is the same. Works both ways of course if you are using the DC CCS then the other car can't use the cdaemo DC charger.

 

[Mgkev]

Thanks for this info guys, really helpful for when I venture further a field. Luckily there seems to be a few new rapid chargers installed during lockdown.

 

[DangerousDoug]

The EU (and by extension the UK) has standardised on CCS and have stipulated that all new EVs sold in the EU must have the Type2/CCS charging connector. This means that all new RAPID chargers installed in the UK will be CCS, with some also including the legacy CHAdeMO connector (the japanese standard, used by old Nissan Leafs) as there are still a lot of previous generation Leafs on the road. Most existing RAPID chargers have both CCS and CHAdeMO connectors, although as already pointed out, each charger station can only use one at at time, as they're conected to the same back-end supply in the unit.
The MG can accept a max. 50kw charge from a CCS, so connecting to a new 150kw station won't give you a faster charge than a 50kw (in theory - I'll be interested to see actual expreience from forum members as these chargers continue to roll out).

 

[Chrispydoc]

Interesting stuff.....it was similar to the old Betamax V VHS issues.

Just out of interest what do Tesla use?

 

[Nibloprice]

I believe Teslas use a type 2 charger (not ccs) but the tesla charging point talks to the car, and then to teslas payment servers so there's no way of using teslas many charing points at service stations.

 

[Mike SOS]

Whistle on the subject of charging battery. Is there any true in a battery needs a full charge at times to maintain the memory?

 

[DangerousDoug]

Whistle on the subject of charging battery. Is there any true in a battery needs a full charge at times to maintain the memory?

there is no "memory" as such in a Lithium Ion battery, but the battery management system monitors the voltage of all the cell groups and periodically conducts a "balancing" operation to bring them all to the same level. This process takes place while "slow" charging (up to 7kw, so granny charger or Type2 fast charging) after the battery pack headline voltage reaches maximum. The indication that the car has started balance phase is that the LEDs in the front badge change from pulsing to steady on (the screen inside the car reports "charging complete" but the car still draws some current from the charger, and the LEDs stay on). This process takes an hour or so. Therefore it's a good idea to let your car fully charge on the wall charger every week or two.

 

[Mike SOS]

there is no "memory" as such in a Lithium Ion battery, but the battery management system monitors the voltage of all the cell groups and periodically conducts a "balancing" operation to bring them all to the same level. This process takes place while "slow" charging (up to 7kw, so granny charger or Type2 fast charging) after the battery pack headline voltage reaches maximum. The indication that the car has started balance phase is that the LEDs in the front badge change from pulsing to steady on (the screen inside the car reports "charging complete" but the car still draws some current from the charger, and the LEDs stay on). This process takes an hour or so. Therefore it's a good idea to let your car fully charge on the wall charger every week or two.

Thanks for the reply. But a little confuse why is it necessary to have a full charge every week or two weeks? at the present I am quite happy to have 80-100 miles range, as I charge at Tesco, Shopping centre, Wickes or Costco. However they are only a short charge of about an hour to hour and half.

 

[DangerousDoug]

Hi, it's not essential, but recommended, as the balance phase only begins when the charge has reached 100%. If you're charging to 60-80% all the time, balancing is not so necessary, as it's very unlikely that any cells will be over-charged. However if you do charge to 100% at some time, it becomes more relavent as you may have some cells which could over-charge, and some which still lag behind. During the balancing process, any cells which are lagging behind in charge level will be topped up, and any cells which were picking up more charge will be trimmed down. The manual recommends this process is allowed to happen every couple of weeks. Again, if you only ever charge your car to 60-80%, it may not ever be necessary, but I won't go against the advice in the manual on this forum .

 

[Portgordon]

My dealer did tell us just before departing that the ZS was only capable of accepting 7KW max via AC - which piqued my interest as it’s not something that had come up in my research about the car to that point. It’s not an issue from my perspective as I’m only ever likely to be AC charging at home where I only have the option of <7 anyway. Away from home would likely always be DC unless I’m borrowing someone elses AC - I suppose in these situations it might come up at some point that a business or somewhere has greater than 7KW AC available and by that time I will have forgotten this information and be scratching my head about why I’m not achieving faster rates! Still a very interesting point though.

Thanks @Frank for the good descriptions of the terminology too, that‘s made it much more clear to me, especially the difference between fast and rapid. I’ll also move to saying slow charge instead of “Granny Cable” - anyone know where that term came from?

I do wish that the cars screens could tell you more clearly and more accessibly how the charging process is going and in particular, show a nice Clear KWh figure instead of Volts and Amps. I feel like volts and amps should be something that’s buried away in a screen for the engineers or added as an option and a simple display of kWh which everything is else is already measured in would make more sense to the general punter. I’m not that keen on having a maths test every time I’m charging

 

[DangerousDoug]

Absolutely agree regarding charging info screen on the car - it's one aspect of the very inferior software on the MG compared with other EVs (in the European market, that is!).

As for charging, I think the info on the car was clear regarding AC charging. To recap, AC charging works via an on-board charger on the car. The "chargers" we talk about (home wall chargers, granny charger etc) are not actually chargers; they're Electric Vehicle Supply Equipment (EVSE) which simply provide 230v mains directly to the car, along with a signal indicating to the car how much current it is permitted to draw. The actual charging function is carried out by the big rectangular silver box on top of the motor under the bonnet (the actual "charger"). There are two types of supply; single phase and three phase. Each phase can draw a maximum of 32A, so single phase can supply a max 7.3kw (32 x 230 / 1000). If your car charger can support 3 phase AC input, then plugging that car into a 3ph EVSE point (AC fast charger rated at 22kw will be 3phase) will supply three "live" connections at 32A each, with a single Neutral. Most older UK homes do not have 3 Phase mains supply to the building, so it's not possible to install an EVSE greater than 7kw capacity. If you have a newer property with 3Phase to the building, you could potentially install a 3phase AC EVSE, which would charge your car 3 times quicker (if your car has a 3phase capable charger - the MG doesn't). In practice this is almost always unnecessary for domestic users, as even the largest battery cars currently on the market will easily charge overnight on a 7kw charger (given that you're almost never charging your car from completely empty!!).

CCS adds the DC connectors which have direct access (via a BIG relay) to your car battery, so all the charging intellegence resides in the external charger post (so Rapid chargers are truly "chargers"). The car will tell the charger (via the type2 signal connectors) how much current it's battery can tolerate (hence the "50kw max charging" spec for the car) even if the charger post is capable of supply much higher current. The DC connectors in the CCS standard are capable of handlying very high currents (much higher than current chargers can supply) making it a future-proofed standard for the foreseeable.

 

[Frank]

My dealer did tell us just before departing that the ZS was only capable of accepting 7KW max via AC - which piqued my interest as it’s not something that had come up in my research about the car to that point. It’s not an issue from my perspective as I’m only ever likely to be AC charging at home where I only have the option of <7 anyway. Away from home would likely always be DC unless I’m borrowing someone elses AC - I suppose in these situations it might come up at some point that a business or somewhere has greater than 7KW AC available and by that time I will have forgotten this information and be scratching my head about why I’m not achieving faster rates! Still a very interesting point though.

Thanks @Frank for the good descriptions of the terminology too, that‘s made it much more clear to me, especially the difference between fast and rapid. I’ll also move to saying slow charge instead of “Granny Cable” - anyone know where that term came from?

I do wish that the cars screens could tell you more clearly and more accessibly how the charging process is going and in particular, show a nice Clear KWh figure instead of Volts and Amps. I feel like volts and amps should be something that’s buried away in a screen for the engineers or added as an option and a simple display of kWh which everything is else is already measured in would make more sense to the general punter. I’m not that keen on having a maths test every time I’m charging

Hi,

The term "Granny Cable" quite simply originated from the fact that stereotypically Granny's are slow and that is apparently all there is to it.

Frank .

 

[DangerousDoug]

I heard that the name derived from the fact that it's the charger you use when visting your granny (or other remotely resident family member)... not sure where that interpretation came from, though. I think Frank's explanation is the more plausible....

 

[Frank]

I think someone was heard to say when a person was just about to charge their car from the 3 pin charging lead, "bloody hell man, don't use that, " it's as slow as your Granny"

?