MG 5 Battery Pre Heat ?

MickeySw said:
Correct, (all?) MG5 have a manual battery heating option but it’s function differs to MG4 (ZS?)

On the MG5 (Trophy) it’s called ‘Battery Heating While Driving’ and its purpose is to increase rapid charging rates. You have to time it exactly so the temperature is at max just before you start DC charging.
For best results use an OBD dongle/app to monitor battery temperature.

See also

Pre heating and Tesla charger

I drove to Leeds and back in the last few days and thought I'd give the Tesla charger at Trumpington (Cambridge) a go. On the way up I only seemed to get 30-35 kW on the way back down I thought I'd give the battery pre-heating a try and put it on 30 mins before the stop and charged at 70-75kW...
www.mgevs.com www.mgevs.com

MG4’ s ‘Intelligent Battery Heating’ is used to pre-heat the battery before driving.
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Mine is a pre face lift Exclusive 5 so it might work or it might not.
 
StevieM said:
Okay, thanks. So would I be correct in saying -battery heating while driving- if the car has been stationary all night and cold, it wouldn’t warm up the battery?
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No, as long as the cell temp is below 10deg it will start heating the battery.

Never tried to see how warm the battery gets while stationary, but as soon as the heater stops, the battery cools down rapidly.

Only when the cells have dropped below 10deg, can one manually activate the function again.

I suppose if you really feel the need to pre-condition the battery before driving, (mis-) use this function, works even better when the cabin heat is turned to max also.
 
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2021 PFL has a manual battery heater which I tried out last year driving back from Scotland. So I left our hotel ambient temperature -1c and drove for an hour which consisted of about 70% motorway and put the battery heater on half an hour before my arrival at a Gridserve charger. I noticed my miles per kWh drop a fair bit. Unfortunately the speed I received was only 40kW on a 150 charger. Ambient temp was 2°C. In my opinion it wasn't worth putting it on. When I think how much more energy it used and 79kWh to replace it. I haven't used the battery heater since.
 
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Rookery said:
2021 pfl has a manual battery heater which I tried out last year driving back from Scotland. So I left our hotel ambient temperature -1c and drove for an hour which consisted of about 70% motorway and put the battery heater on half an hour before my arrival at a Gridserve charger.
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After an hour’s drive your battery temp would have been around the 10 deg mark
Rookery said:
I noticed my miles per kWh drop a fair bit.
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It’s a 3kW heater, the motor is rated over 100kW but if you drive very efficiently then the additional load will have an effect.
Rookery said:
Unfortunately the speed I received was only 40kWh on a 150 charger. Ambient temp was 2c.
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It looks like the heater didn’t activate at all as the cells were just above the threshold.
Rookery said:
In my opinion it wasn't worth putting it on. When I think how much more energy it used and 79kW to replace it. I haven't used the battery heater since.
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30min @ 3kW isn’t a lot, not sure where you got the 79 kWh from?

But you’re right, usage of the battery heater only makes sense if you’re in a hurry to do long distance journeys that require multiple rapid charge stops.
 
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I understand all that however it was a test if the heater makes any appreciable difference which in my opinion it didn't. I was driving about 60 - 65 mph which I think is reasonable. When I put 79 kWh I missed out the p for pence. I have had the car over 3 years and I have a pretty good idea on its charging speeds in all weathers and as I stated in my opinion it wasn't worth it. There is one thought it may be the charger because they do vary somewhat.
 
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Rookery said:
2021 pfl has a manual battery heater which I tried out last year driving back from Scotland. So I left our hotel ambient temperature -1c and drove for an hour which consisted of about 70% motorway and put the battery heater on half an hour before my arrival at a Gridserve charger. I noticed my miles per kWh drop a fair bit. Unfortunately the speed I received was only 40kWh on a 150 charger. Ambient temp was 2c. In my opinion it wasn't worth putting it on. When I think how much more energy it used and 79kW to replace it. I haven't used the battery heater since.
Click to expand...

I've never been able to get much over 40kW on a 150kW charger no matter the time of year. I think some just don't play well with the MG5. I pulled up to a 100kW charger next to an MG4, he was getting close to 100kW and the best I got was about 39. Admittedly a cold day but as I said I've never really got much more than that. On a 50kW there doesn't seem to be the same issue.
 
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Rookery said:
I understand all that however it was a test if the heater makes any appreciable difference which in my opinion it didn't.
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Without monitoring cell temperatures you have no idea what caused the ‘no difference’ in charge rates but I’ll put my money on the heater not ‘firing’ at all…

But even if it did, 30min probably won’t be long enough to get the battery to the 30deg optimum temperature…
 
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5teep said:
I've never been able to get much over 40kwh on a 150kw charger no matter the time of year. I think some just don't play well with the MG5.
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Not my experience, I remember 70-80kW average on a 150kW during summer on our FL Trophy.
 
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MickeySw said:
Without monitoring cell temperatures you have no idea what caused the ‘no difference’ in charge rates but I’ll put my money on the heater not ‘firing’ at all…

But even if it did, 30min probably won’t be long enough to get the battery to the 30deg optimum temperature…
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I believe the heater did come on because I was getting 3.7 miles per kWh and it gradually dropped to 2.4. after the heater went on.
I must admit an hour of driving at reasonable speeds and the battery heater on I did expect more power comparing with other occasions when I haven't used the heater in similar circumstances and received a higher charge rate at approx the same state of charge. There other factors which can influence your charge rate when all the chargers are busy and power can be reduced or even the charger itself is not working properly.
 
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I am still very new to this charging scenario.
I gather that depending how empty of charge the battery is when you start to charge, it will affect the speed.
If the battery is low, you get quick charging speed if the battery is close to full you get a much slower charging speed.
So possibly when you turn on battery heater, it still depends on how full or empty your battery is.
Perhaps the car is protecting the battery from a too quick charge whatever is done to heat the battery.
Apologies to all if I have got the wrong end of the stick in saying the above.
 
On a DC Rapid charger it's like a curve, 0-20% starts slow, then 20-80% it speeds up and slows down in a long gentle curve, 80-90% it slows down and 90-100% it gets so slow you'd be faster on a 7.5kW AC charger.
[ edit It does this to protect the battery from damage by overheating. ]

Fastest charging speeds are usually around 50-60% but that's car dependent.
 
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StevieM said:
So possibly when you turn on battery heater, it still depends on how full or empty your battery is.
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Yes, but the cell temperature is the determining factor, SoC has a lesser influence in cold weather.
StevieM said:
Perhaps the car is protecting the battery from a too quick charge whatever is done to heat the battery.
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Also correct, the BMS will restrict the charge rate if the cells are not at optimal temperature (around 30deg for NMC / 40deg for LFP).


The whole purpose of the manual heater is to ensure your cells are ‘hot’ just as you plug in; then your charge rates will be determined by SoC only.
 
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My car is a short range MG5 with a 51kwh LFP battery,
Tonight it was -7.5c and i charge my 51kwh battery from 38% to 69% and that will be approximately 15.8 kwh, my charger has drawn 15.6 kwh so if the battery heater was on i believe it will not land on 69% soc, but instead more less than that.
So i wondering how or if the preheating works.
Charge a LFP in so cold weather without preheat is not good for the battery if google is to be believed. I need to find a way to monitor the cell temperature.
 
timmpo said:
My car is a short range MG5 with a 51kwh LFP battery,
Tonight it was -7.5c and i charge my 51kwh battery from 38% to 69% and that will be approximately 15.8 kwh, my charger has drawn 15.6 kwh so if the battery heater was on i believe it will not land on 69% soc, but instead more less than that.
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IIRC only about 46kWh of your 51kWh LFP battery is actually usable.
timmpo said:
So i wondering how or if the preheating works.
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The BMS should heat the cells to above freezing before charging [Edit: apparently not, see post 39]
timmpo said:
. I need to find a way to monitor the cell temperature.
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Get yourself an OBD dongle and app
 
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yes the BMS should... But i have not seen any indication in the power logs when charging in way below sub zero temperatures, when i have charge at 10kw the charger directly starts at 10kw and i doubt the heater draw that much, so some amps will go to the battery. Tonight the settings in the charger was at 4kw and it started at 4kw so if the heater element is rated at 3kw some power still going to the battery.
 
timmpo said:
yes the BMS should... But i have not seen any indication in the power logs when charging in way below sub zero temperatures, when i have charge at 10kw the charger directly starts at 10kw and i doubt the heater draw that much, so some amps will go to the battery. Tonight the settings in the charger was at 4kw and it started at 4kw so if the heater element is rated at 3kw some power still going to the battery.
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Interesting..

Edit: Below are quotes from the MG5s 'Principle and Functions manual':

Page 29:
The Battery heater is used to heat the battery at low temperature when using a rapid charger. It is controlled by BMS. The heating power of the battery heater is no less than 3.5 kW under rated working conditions. With the increasing of the inlet water temperature, the heating power tends to decrease. When charging at low temperature, the heater can shorten the fast charging time of high voltage battery.

Page 54:

In the case of fast charging under low temperature, the ESS battery cooling cycle can be started. The high-voltage battery heater (PTC) heats the battery coolant, and the heat is transferred to the battery by the rotation of the water pump to achieve the purpose of heating the battery.

Water pump control: when the minimum battery temperature is less than a certain value, the BMS controls the battery water pump to On; when the minimum battery temperature is higher than or equal to a certain value, the BMS controls the battery water pump to Off.

High-voltage battery heater (PTC) control: when the battery water pump is turned on, the high-voltage battery heater(PTC) receives the LIN signal from BMS, turns on the heating function, and adjusts the output power in real time to warmup the high-voltage battery pack in an optimal manner; when the battery temperature rises to a certain value, the BMS controls the battery heater (PTC) to stop heating before turning off the water pump


Above seems to suggest that the battery heater's is primarily function is to increase charge rates and not to prevent cell damage? Therefore what you observed seems to be normal?


To verify you can monitor the RPM/Voltage/Current display and see how much power goes directly into the battery.

A quick way to test the heater itself is to manually turn it on when cell temperature (ambient) is below about 10deg, you should see a jump in current on the RPM/Voltage/Current display if it’s working.

Best way to observe heater efficiency is to monitor battery temperature via OBD.
 
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i have connected a odb dongle and tested the heater from in car, with the battery temp at -0.5c the heater draw around 10amp (info display at 0 before start) and 10 amp at 394v is around 3,9kw and in the service manual from a pre facelift it is spec at 3.5kw but will increase some when the water inlet temperature gets higher.

But interesting is that i can clearly hear the feeding-pump when i start the heating but i have never hear it when i connect the charger.

the service manual does only mention that the BMS starts the PTC heater in the case of fast charging.
 

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