There's no way to charge a 2021 MG5 to 80%?

[Joe Boatman]

I thought the MG5 Owner's handbook recommended charging to only 80% when using a home 7kW charger with a monthly charge to 100% for Equalisation Charging or a 100% charge for long journeys, but I can't find this.

My home Hypervolt charger provides no way to charge to a given percentage and the company confirms that this is not possible because there's no feedback from the car to the charger. Since the car infotainment system does not provide this either, and there's no app, here's my method.

Octopus supplies our electricity and allows a lower cost night rate between 00:30 and 04:30.

The Hypervolt allows this timed charge and also allows me to vary the charging current from 6 to 32 amps. This means that if I know the mains voltage (240 VAC) and I set the current to 10 amps then I will pump 2400 watts (2.4 kW) into the car, and assuming 100% efficiency, 2.4 kW goes into the battery.

So, after 4 hours, I will have put 2.4 x 4 = 9.6 kWh into the battery. At 20 amps, I can shove twice the power into the battery, and so on.

The 2021 MG5 Exclusive SW has a 53 kWh battery, so if it's 40% charged, then I need 60% of 53 kWh for a full charge: 31.8 kWh.

I can get 31.8 kWh at 240V over 4 hours by setting the current to 31800 / (240 x 4) = 33 amps!

Please bear with me. I know that the car charger stops charging when it gets to 100% so there's no need to bother with the maths providing I've got a minimum of 40% charge in the battery and 4 hours of charging.

However, at 100% charge, there's no regen; driving feels weird! Also, I prefer to charge only to 80 or 90%.

The easiest way is to do the maths assuming the battery contains 80% of 53 kWh (42.4 kWh) and the below table lists the current required to charge the battery to 80% in 4 hours.

Battery % before charge​	Calculated kWh required from Charger​	Set charging current to (6-32A)​
80%​	0​	0​
75%​	2​	2​
70%​	4​	5​
65%​	6​	7​
60%​	8​	9​
55%​	11​	12​
50%​	13​	14​
45%​	15​	16​
40%​	17​	18​
35%​	19​	21​
30%​	21​	23​
25%​	23​	25​
20%​	25​	28​
15%​	28​	30​
10%​	30​	32​
5%​	32​	35​
0%​	34​	37​

I created a spreadsheet so you can enter your vehicles battery capacity, the mains voltage, charging period and the percentage level of charge required. Then the above figures relate.

A final note: you may want to reduce the car's power capacity a little after a few years and check your mains voltage - the above table is for 230 VAC.

 

[Jomarkh]

With my Zappi I adjust the time in the schedule, my commute is 70 miles, so in the winter I add about 3 hours or so and in the summer 2.5 hours. That gets me to between 80-90% depending on how cold it is over night.
I too like feel of one pedal driving in kers3.

 

[dragon2611]

I usually let ev.energy manage my charger and have it set to only use off-peak although I have found occasionally the charger doesn't get told to shut off and I ended up charging to 100% anyway.

There is a basic schedule on the chargers own app I could use but I prefer the ev energy app in most cases.

 

[Joe Boatman]

I usually let ev.energy manage my charger and have it set to only use off-peak although I have found occasionally the charger doesn't get told to shut off and I ended up charging to 100% anyway.

There is a basic schedule on the chargers own app I could use but I prefer the ev energy app in most cases.

Thanks, Dragon2611. I'm not sure how ev.energy helps. Perhaps I don't understand what the app does especially as MG is not listed on the compatibility page at Integrations New

 

[dragon2611]

Thanks, Dragon2611. I'm not sure how ev.energy helps. Perhaps I don't understand what the app does especially as MG is not listed on the compatibility page at Integrations New

It just tells the charger to charge when power is cheaper, but as you say there's no way to know what %age the car is at.

The only reason mine usually doesn't goto 100% is because it's low enough when I plug it in and there isn't enough time (at the cheap rates) for it to.

 

[Petriix]

I think you're over complicating it. At 6.6kW the MG5 SR charges at roughly 12.5% per hour or around 1% every 5 minutes. Simply set the timer on the charger accordingly.

 

[Lovemyev]

I think you're over complicating it. At 6.6kW the MG5 SR charges at roughly 12.5% per hour or around 1% every 5 minutes. Simply set the timer on the charger accordingly.

Rough estimate is one hour on charge on a wall box, adds roughly 25 miles of extra range to the battery.

 

[Joe Boatman]

I can understand that, but my Hypervolt app has a slider to set the current and this is easier than changing the length of time that the charger charges.
I intend to ask Hypervolt to add a new easy-to-use slider based on raising the current battery charge from n% to a pre-set max eg 80%. In this way I read the current charge on the car's screen and move the slider on the app to the same figure knowing that the charge period of the fixed 4 hour slot will charge to 80%.

 

[Jomarkh]

How do you take into account the cold weather as I find a cold battery takes more charge as some is lost in warming it up?
If you charge at a lower current does the battery not warm up at all?

 

[Joe Boatman]

How do you take into account the cold weather as I find a cold battery takes more charge as some is lost in warming it up?
If you charge at a lower current does the battery not warm up at all?

I don't know!!
Perhaps that explains the difference between the current I set the Hypervolt wall charger and the charge I end up with. For example, I set it to charge to 80% last (very cold) night and this morning it read 76% on the screen.

PS: I hate not knowing how this car of mine works! I know how our ancient petrol Vectra works and I drive it accordingly and understand the noises it makes when bits fail. Too much of the new beasty is hidden.
And where's the MG5 Haynes manual when you want one? There isn't one:

 

[Gomev]

...

PS: I hate not knowing how this car of mine works! I know how our ancient petrol Vectra works and I drive it accordingly and understand the noises it makes when bits fail. Too much of the new beasty is hidden.
And where's the MG5 Haynes manual when you want one? There isn't one:

..

Most of the failing noises are the same, apart of course from anything to do with engines, gearboxes and exhausts. That doesn't leave a lot to be hidden, a battery and a motor.

When you filled your Vectra did you play about with the pump speed or did you just stop when you had got your £20 worth ?

Just think of it as a wild cross between a car and a washing machine.

 

[Joe Boatman]

Most of the failing noises are the same, apart of course from anything to do with engines, gearboxes and exhausts. That doesn't leave a lot to be hidden, a battery and a motor.

When you filled your Vectra did you play about with the pump speed or did you just stop when you had got your £20 worth ?

Just think of it as a wild cross between a car and a washing machine.

You are right Gomev! Perhaps in my mind it's the software that distances me.
When filling V-for-Vectra wth petrol, you're also right that I fill it until the pump stops. But I'm not supposed to do that with MG5 EV. I understand that I must fill it to 80% - and the 'pump' doesn't stop at 80%!! Later MG5 models (mine's the first edition) can do this. My Hypervolt wall unit's software can't do it either.

 

[dragon2611]

You are right Gomev! Perhaps in my mind it's the software that distances me.
When filling V-for-Vectra wth petrol, you're also right that I fill it until the pump stops. But I'm not supposed to do that with MG5 EV. I understand that I must fill it to 80% - and the 'pump' doesn't stop at 80%!! Later MG5 models (mine's the first edition) can do this. My Hypervolt wall unit's software can't do it either.

It's not the end of the world if you charge it past 80%, although ideally don't leave it in that state for weeks on end.

 

[emmrecs]

@Joe Boatman

I have the pre-facelift MG5 also and, like you, cannot set any charge "percentage" in my ev.energy app; the only option is to set a time by which the car should be "ready", in my case, 07:00, and that's 100% charged.

But I fully agree with @dragon2611 I honestly don't think it's worth worrying about! My understanding is that that 80% figure applies very much more if the car is being regularly charged using Rapid or even Ultra-Rapid chargers. I've used such chargers only three times in very nearly a year's ownership, every other charge used my home 7kW Rolec and I have seen no obvious degradation in performance over that period. I remember my dealer telling me, when I first took delivery, that it is rather more important to make sure that at least once every month a full balancing charge was done, especially if one tends to use Rapids or Ultra-Rapids "regularly". With a home charger I believe that balancing occurs after every charge.

 

[Gomev]

You are right Gomev! Perhaps in my mind it's the software that distances me.
When filling V-for-Vectra wth petrol, you're also right that I fill it until the pump stops. But I'm not supposed to do that with MG5 EV. I understand that I must fill it to 80% - and the 'pump' doesn't stop at 80%!! Later MG5 models (mine's the first edition) can do this. My Hypervolt wall unit's software can't do it either.

Mine is a Mk1 LR and I charge by percentages/time. At the full whack '7kw' it adds approx 10% per hour, maybe a little more, so I go on that.
I'm on Octopus Go so with 4 hours overnight charging I know I'm going to get 40 ish % percent added.

 

[dragon2611]

I forgot I’d turned off only charge off peak on my charger the other day it seems and thus charged more than I meant to overnight.

Oh well other than costing more due to using some peak rate electricity it’s not really an issue

 

[MGBok]

I think you're over complicating it. At 6.6kW the MG5 SR charges at roughly 12.5% per hour or around 1% every 5 minutes. Simply set the timer on the charger accordingly.

I wouldn't worry about it, ive got a 70 plate and top up where I can in short bursts (2hrs here & there) but when I charge overnight I leave it to 100%. This happens around every 3 weeks when it's dropped to around 20%.
I will keep the car for max 10yrs, after that it's not my problem. Anyone buying after that it's buyer beware, just with an ICE car... These are budget cars, so I'm guessing the battery will outlast the rest of the car

 

[Olivarus]

Talk about creating a problem that isn't there! Please don't raise a ticket with Hypervolt, they're far too polite to tell you what to do with it! In the time that it took you to create a spreadsheet you could have adjusted the length of charge on your Hypervolt many, many times over. I like spreadsheets, but get real! As others have said, in warm weather my Hypervolt charges at a little over 10% per hour and, in the winter, a little under. 80% is not a precise requirement, so it doesn't matter if it's 82% or even 84%. Think of all the time that you've lost when you could have been out enjoying a drive in your car

 

[Padaung]

I think you're over complicating it. At 6.6kW the MG5 SR charges at roughly 12.5% per hour or around 1% every 5 minutes. Simply set the timer on the charger accordingly.

This is exactly what I do too (I have the same car as the OP).

My wallbox (EO Mini Pro 2) only allows me to set the charge time in 30min segments so I've made it easy on myself and estimage the charge to be around 12%/hr or 6%/30mins with a 7kW charger.

So I just set the charge time to give me a charge in the range of 80-85%. I've found that whilst winter temperatures do give a slower charge, the charge rate isn't affected anywhere near as much as the actual range is with cold weather, so I still stick to the 12%/hr charge calculation.

And as suggested, every once in a while the car is charged to the full 100% anyway.

Anyway, the above allows me to do the mental arithmetic for the charge time required by the time I've walked back into the house from plugging the car in and has proven to be a reliable system over the (very nearly) 2 years we have had the car.

 

[Madgermusso]

Do what I do, plug it in every night to top it up to 100% and be done with it! No hassle, job done. I'll be going back to petrol when my cheap rate ends in July, so any impact on battery life won't be my problem