How To Charge To 80%

[EV Day]

Hi all,

I’ve just bought my first EV, a MG ZS mark 1 2021 and have read that you should only charge the battery to 80%.

But how do you charge it to 80%? I’ve got a Hive home charge and it charges overnight but is there a specific way to only charge to 80%?

 

[hmadsen]

In the charge menu in the infotainment system in the car, you should be able to set it to only accept a charge to 80%

Please remember that the "hive home charge" box and any other home charge boxes are not really chargers.

When charging at home or any other place where you AC charge at 7/11 KW the charger is actually in the car.

The box on the wall is merely a box with some electronics and some relays to connect the car directly to the grid.

The electronics communicate with the car, about what it is capable of delivering and the car then initiates a charge and set the onboard charger to adhere to these limits.

So what happens when you plug in is.

1. Car asks the wall box to get some power.
2. The wall box says "Yes, i can deliver X amps on Y phases"
3. The car replys "Acknowledged, please start charge"
4. The wall box then energizes the relays inside, effectively connecting the power from the grid, directly to the car's onboard charger.

The charger in the car will not ramp up to anything beyond what the wall box said it, and the connected cable is rated for.

 

[Jomarkh]

Hi all,

I’ve just bought my first EV, a MG ZS mark 1 2021 and have read that you should only charge the battery to 80%.

But how do you charge it to 80%? I’ve got a Hive home charge and it charges overnight but is there a specific way to only charge to 80%?

You have to work out how much to add either as a percentage of you battery or in kWh.
You get home with say 40% then add 40% or 30kWh?

 

[EV Day]

Thanks both for the help and advice, really appreciate it. Not managed to find the setting yet, but have 2 young children with chickenpox at the minute so not had a proper look

 

[Tim Green]

EV DAY: I think Hmadsen above is referring to the MK2 ZS. The MK1 does not have the capability to set the max charge to anything but 100%.

 

[EV Day]

EV DAY: I think Hmadsen above is referring to the MK2 ZS. The MK1 does not have the capability to set the max charge to anything but 100%.

Thanks Tim, I wondered why I couldn’t find anything last night when I had a Quick Look. So it’s just a bit of pot luck as to how much is charged. I can control the the finish by time, so will set that earlier in the morning and see if that works. Thanks

 

[Gadget Geek]

You could do a bit of back of the envelope maths to get you a rough target.

I presume you have the 50.3kWh battery. If your EVSE is outputting 7kW then in 7 hours you will have added 49kWh, that's 7kWh every hour.

80% of 50kWh is 40kWh. You can then work out how many hours you need to charge using multiples of 7.

 

[Tim Green]

Yes, that's easy. When you're on cheap rate charging it's being up at the appropriate time in the night to stop the charge that's difficult! I could reset the timer each time, but what a hassle.

 

[fred12345]

Hi all,

I’ve just bought my first EV, a MG ZS mark 1 2021 and have read that you should only charge the battery to 80%.

But how do you charge it to 80%? I’ve got a Hive home charge and it charges overnight but is there a specific way to only charge to 80%?

If I were you, I would just plug it in overnight or whenever it's free for you and not worry about 80% ... I don't think it will affect the car battery so much that you have to burden yourself with kWh and % ... relax and enjoy the ride

 

[hmadsen]

Yes, that's easy. When you're on cheap rate charging it's being up at the appropriate time in the night to stop the charge that's difficult! I could reset the timer each time, but what a hassle.

Depending on the charger, it might also have provisions to do stuff like this.

I have an Go-E charger, i can set that up to only charge between certain hours, but it is also possible to set a fixed amount of charge added.

When DC fast charging the DC Fastcharger can communicate with the car and i have seen some that will actually have on the charger screen, what the SoT of the car's battery is.

So when the car and charger communicate, these data must be exchanged, and since the CCS plug is just a Type-2 with the 2 big pins for DC, the communication must be using the pins in the Type-2 connector.

Would be nice if home chargers would be able to speak to the car and get this figure, this way the charger could just be set to "Charge to 80%" and when the car reported 80% SoT, the charger would stop.

Sadly chargers does not seem to support this, even my charger, which is not the cheapest, is unable to speak to my car.

I know Tesla home chargers can be set to only accept specific Tesla vehicles, so they must communicate with the Tesla to know if an approved one is connected, but other than that i know of no chargers that can speak to the car like that

 

[Peterboat]

We have always charged to 100% mostly the car is used the next day so its charge goes down. Our last car the I3 it was advised to always charge to 100% to allow balancing the cells, given that we only charge once or twice a week we fall into the does it really matter camp

 

[Tim Green]

And having owned the car for five years now and always charged at home to 100%, its probably too late to start worrying about it.....

 

[fred12345]

And having owned the car for five years now and always charged at home to 100%, its probably too late to start worrying about it.....

out of curiosity, any idea what is your state of battery health percentage?

 

[Tim Green]

Not right now. However, on Monday (27 Jan) the car goes into Waylands for its 5th annual service. As part of that service they are are supposed to measure and mark on the report the level of battery SOH and %. I will report back next week, and also give last year's level.

 

[Chris H]

With the type of battery in the ZS EV you can charge to 100% with no issues.
Other than that, with Octopus Entergy and a compatible charger (mine is a Zappi) you can just tell Octopus to add x% and it works the rest out for you and creates a charging schedule at cheap rate (7p) and delivers the right amount. Mine is currently at 55% charge, I asked Octopus to add 45% and the photo shows the schedule it created. BTW, with Octopus you can ask it to be ready up to 11am and even though the cheap 7p rate is for everything in the house 11pm-5am, if they schedule the car to charge at other times that is also at the 7p rate. It works really well. If you want to only charge to 80% then in this case you would select to add 25%.

 

[martin181187]

Hi sorry for jumping on this post. I have a MG ZS EV exclusive 21plate. I’m just wondering if anyone maybe able to help as not had much luck with dealer or with product EV. My question is does anyone else have an issue when charging there car at home on a 7kW after its finished its normal full charge my car starts to trickle charge at 1kW. I never used to have this issue always disconnect once charged and turned off now since September October time this hasn’t been the case it keeps trickle charging I had the car in garage they say they can’t find an issue and say to use a 3 pin plug charge and charge car for 24hr done that still it trickle charges on my normal project EV charge I had installed so then project EV replace my old box with a brand new one and still the issue of the trickle charging is happening. So what is causing this problem does anyone else have this issue and if so how can this be resolved/done to fix this thanks

 

[fred12345]

My question is does anyone else have an issue when charging there car at home on a 7kwh after its finished its normal full charge my car starts to trickle charge at 1kwh.

My 2022 SR also trickle charges for a bit after it reaches 100% , that is to balance the battery. It should stop after a while, just let it be and see how long before it stops.

Why was your charger replaced?

 

[martin181187]

My 2022 SR also trickle charges for a bit after it reaches 100% , that is to balance the battery. It should stop after a while, just let it be and see how long before it stops.

Hey ya yeah project EV replaced it as they thought it may have been an issue with the charger as on my charging history it never did it before it always disconnected after it had hit the completion and never stayed charging for over 6 hours but since September October time it’s been staying charging for 12hours. I didn’t notice this till recently as I charge my car over night. Just one more quick question do you know if any of these lights on my 3 pin charger will turn off when it’s finished doing the charge? Thanks

 

[fred12345]

I don't have the MG charger like that but the blue/green light should turn off when charged, hope someone else can also confirm ..

 

[DBedford]

The charger you show Martin needs some TLC, as the cable has come out of its cable clamp, photo top right left.