Understanding the Battery Heater logic on the MG ZS EV LR (2023)

[D4niso]

Hello everyone,

I’ve owned my MG ZS EV Long Range (2023) for a year now, covering about 40,000 km. Recently, I’ve run into a bit of a challenge regarding DC fast charging speeds and the battery heater.

From what I’ve observed, the battery heater only seems to kick in when the battery temperature is below 10°C. If the battery is at 11°C, it stays off. This becomes an issue during winter here in Portugal; while it’s not freezing, the battery often stays just warm enough to disable the heater, but too cold to accept a fast charge.

When driving at lower speeds on country roads, the battery doesn't naturally heat up enough. This results in charging speeds of only 30-50 kW. What should be a quick 7-minute stop often ends up taking double the time.

My questions for the community:

Does anyone have technical documentation or specific insight into the exact logic of this system?

Is there any way (via settings or OBD2 tools) to manually trigger the battery pre-heating?

Are there any "tricks" or driving styles you use to raise the battery temperature before hitting a charger in mild climates?

Looking forward to your insights!

 

[fred12345]

Not what you want to hear but: I would not worry about it too much. I'm not technical enough to go into battery chemistry, temperature and charging speeds but from experience, there is more to it than the temperature - I managed to charge quite fast in winter and quite slow in summer ... It depends on the charger as well as the battery charge level, it slows down fuller the battery is .. Sure way to heat up the battery is to drive sporty and fast but that defeats the purpose, you'll just use up more energy that will keep you charging for longer ...
You can try turning the battery heating on an hour earlier from your iSmart app and see if it makes any difference but as I said, I wouldn't worry about it too much ...

 

[Data]

Battery heaters are not needed or effective unless at 10c or below & really have little effect until near or below freezing. If you car was not charging above 30-50kw it will normally be for other reasons, not temperature unless at or near freezing. As Fred says it depends on state of charge & how powerful the charger you are using actually is. Was someone else using the same charger as you (dual bay shared charger)? That will reduce the charge speed by half. The only time my Long Range ZS has reached maximum charge speed of 94kw's was on a long road trip in the summer with a SOC at 30% & an ambient temp of 25 degrees. The charger was a 180kw DC charger. Most of the time it tops out at 50-60kw at 55-60% soc at around 16 degrees. But it's so variable & can be higher or lower. Don't worry about it. There are no tricks to alter this.

 

[MickeySw]

Does anyone have technical documentation or specific insight into the exact logic of this system?

Assuming it’s the same system as in the MG5 then you’re right, the manual heater won’t start unless the battery temperature is below 10deg.

While driving the battery is keep at roughly 10deg or ambient, whichever is higher.

Even if you manage to get the heater to start, it just turns off once it reaches it’s set temperature, I.e. the battery cools down quickly afterwards, to time this right is near impossible without OBD temperature data.

Is there any way (via settings or OBD2 tools) to manually trigger the battery pre-heating?

Not that I’m aware of..

Are there any "tricks" or driving styles you use to raise the battery temperature before hitting a charger in mild climates?

Our colleges in Germany can ‘floor’ the accelerator for the last 15min before plugging in, seemingly it does have a benefit on multiple stop, long range journeys.

As already mentioned the only other way to heat up the cells is repeated, hard acceleration followed by brisk Kers3 braking, but that may only give you whiplash and unwanted attention from law enforcement?

It’s also thought that this only ‘works’ for NMC batteries..

 

[D4niso]

’ve experienced this after driving at least 350 km on country roads at speeds between 40 and 90 km/h. Because of the low speed, the battery temperature did not even reach 15°C, and my state of charge was around 20–30%. I was expecting charging speeds close to 80 kW, but when I arrived at a 150 kW charger, it started at 45 kW and only gradually increased to 55 kW after some time.

Still, if there is nothing I can do to override this system, then we simply have to accept it. It’s a very frustrating system.

IF the system was able to heat up to 22ºc I would charge in 5 to 7 mins and then go home with charge .

 

[Data]

In summer it'll be much faster. You'll see. But short chargers of just a few minutes never usually reach a fast charge. Even in summer a short charge won't go at maximum speed usually. 5-7 mins indicates you aren't going to put in much. A longer charge will go much faster (reach higher speeds).

 

[D4niso]

That I know, but i do have to travel in every season. Leaving me to take more time in the winter...
There is a manual override inveted by someone for other brands.
Is there anything like it on MG ?

 

[Data]

Not on the ZS.

 

[D4niso]

Not on the ZS.

What other model has this ?

 

[MickeySw]

What other model has this ?

Iirc some MG4’s can pre-heat the battery to increase CCS charge speeds if you select a charger on the built-in SatNav?

 

[Data]

Many MG4s have intelligent battery heating.

Most of us don't usually just stop to charge. We stop to do other things but plug in for a top up. That way you don't waste time.

 

[D4niso]

Many MG4's have intelligent battery heating.

ZS EV has intelligent battery heating.
But it only works if the battery is below 10°C.

 

[Data]

ZS EV has inteligent battery heating.
But it only works if the battery is below 10c

It's not intelligent like the MG4. It's very basic.

Edit: D4niso, it might be more intelligent than I thought. Just realised it's more similar to the MG4 than I thought on the later models like mine. Mine is 2024 model. Not sure about the earlier cars

 

[D4niso]

It's not intelligent like the MG4. It's very basic.

Edit: D4niso, it might be more intelligent than I thought. Just realised it's more similar to the MG4 than I thought on the later models like mine. Mine is 2024 model. Not sure about the earlier cars

What's the difference ?

 

[Data]

What's the difference ?

You'll need to look at the different manuals for the ZS & MG4 to find out. However, don't get fixated with battery heating. We all need to charge in all seasons, you are not unique. Here in the UK battery heating is hardly ever needed except in the coldest of winter nights in the northern regions of our country. I've used it once in the last 16 months & it made little difference to anything as far as I could tell. Even without heating at 2 or 3 degrees above freezing my car reached a decent (70-75kw speed after 15mins of charging. Admittedly this was on a longer run but it's what you can often expect with NMC batteries. It started at 45kw's of speed on a 180kw DC charger.

The way most of us do it on a longer run for example is like this. After a couple of hours driving I've normally covered around 110-120 miles depending on the sort of roads I'm driving on. Many of us need to stop for tea or coffee, bacon roll & a wee! So after stopping just plug your car in to a charger, over here they are mostly everywhere, & go & order your food & get a table. It takes around 25-30mins to get the food etc & be ready to get under way again. This means the car is completely full again with no time wasted. Simples!

I'm more concerned as to why you are so fixated on charging your car in 5-7 mins? That's not how it works & I think you have over estimated what is possible most of the time. You will never charge your car properly at speed & put any worthwhile amount of power into the car trying to do it that way. The battery internals won't warm enough to get you any real speed. Of course put the battery heating on prior to reaching your charging station & experiment. Let us know how it goes.

 

[D4niso]

You'll need to look at the different manuals for the ZS & MG4 to find out. However, don't get fixated with battery heating. We all need to charge in all seasons, you are not unique. Here in the UK battery heating is hardly ever needed except in the coldest of winter nights in the northern regions of our country. I've used it once in the last 16 months & it made little difference to anything as far as I could tell. Even without heating at 2 or 3 degrees above freezing my car reached a decent (70-75kw speed after 15mins of charging. Admittedly this was on a longer run but it's what you can often expect with NMC batteries. It started at 45kw's of speed on a 180kw DC charger.

The way most of us do it on a longer run for example is like this. After a couple of hours driving I've normally covered around 110-120 miles depending on the sort of roads I'm driving on. Many of us need to stop for tea or coffee, bacon roll & a wee! So after stopping just plug your car in to a charger, over here they are mostly everywhere, & go & order your food & get a table. It takes around 25-30mins to get the food etc & be ready to get under way again. This means the car is completely full again with no time wasted. Simples!

I'm more concerned as to why you are so fixated on charging your car in 5-7 mins? That's not how it works & I think you have over estimated what is possible most of the time. You will never charge your car properly at speed & put any worthwhile amount of power into the car trying to do it that way. The battery internals won't warm enough to get you any real speed. Of course put the battery heating on prior to reaching your charging station & experiment. Let us know how it goes.

In my recent trips I only needed 10% to 15% extra to reach my destination.
In theory, 5-10 mins on the max charge, would do.
That's why it would help, that extra juice would let me go home and be there with 5-10% remaining
I've been doing that sometimes, stopped for a wee, get a coffee and charging is done.
Just checking if it was possible to override the situation, cause if it was, I would stop charge, do a wee and go home, not more time spent.
But if you arrive with a cold battery, instead of getting 79+KW you get 30-40.
Since there's is nothing we can do, I've just accepted it.

 

[Data]

It's pretty much the same no matter what EV car you drive. We have 5 EV's in our family including my MG. Even though a couple of them have much faster charging ability they all start charging at quite low speed eg: 40-50kw's on 250kw chargers. It's not until they have been charging for 10-15 mins or more that charging speeds ramp up to 80-100kw's or more. Our E-Niros are about the same as our MG's in terms of charge speeds. In reality I rarely charge in public for more than 20mins. That usually puts about 120+miles in the tank in reasonable ambient temps.

 

[MickeySw]

Even though a couple of them have much faster charging ability they all start charging at quite low speed eg: 40-50kw's on 250kw chargers.

To reach max charging rates the battery needs to be at optimum temperature (the fingerprint in most specs states around 25C).

Unless ambient temperatures are of that magnitude, it will take a couple of minutes for the cells to warm up when charging.

The whole idea of pre-condition a battery is for it to be at optimum temperature just as you start a rapid charge.

It certainly doesn’t work as intended on ‘older’ MG EVs, not sure how the latest model range performs though..