Indications for using battery heating (now the weather is getting colder)

[siteguru]

I've been away this weekend and had my SoC down to low 30s and 40s % a few times ... I didn't notice any colour change to the SoC indicator.

 

[davejohn]

Does the bug affect cabin pre-heat, battery pre-heat or both?

I decided to do a battery pre-heat this morning. Started it 90 minutes before departure; app said it was on. Looked again 30 minutes before departure and app said it was off.

you only need about 10 mins. for it to work and it does turn itself off after a short while to save unnecessary battery use

 

[Rolfe]

I've been away this weekend and had my SoC down to low 30s and 40s % a few times ... I didn't notice any colour change to the SoC indicator.

I wasn't expecting it. Hardly anybody has been complaining about it. It's no big deal, it's just silly.

 

[Mike80]

I can find no evidence for warming the battery except prior to a Fast/DC charge. According to the MG tips MG Winter tips for electric motorists - MG Motor Europe

The temperature of the battery will increase by normal driving and AC charging. At low battery level combined with low external temperatures and a cold battery, you may experience less power than normal. This adjusts when the battery reaches a normal working temperature.

As my dealer said when I asked “why would you want to accelerate quickly in cold/icy conditions”

There is also this video from a driver/reviewer in Denmark, only mention of battery warming is prior to a DC charge.

Driving in a Cold Climate

 

[tsedge]

I've been away this weekend and had my SoC down to low 30s and 40s % a few times ... I didn't notice any colour change to the SoC indicator.

For me, I would expect yellow below 20%, red below 10%, something like that would be sane behaviour.

 

[Mickser]

Hi by not using battery heating in the winter will it damage the health of my battery, I never fast charge and do a round trip of 12 miles 5 days a week for work and I have never used the battery heating option, thanks.

 

[siteguru]

Your LR battery is less impacted by cold weather than the LFP pack in the SR car, so don't worry about it. Even in my SE SR I've rarely used battery heating. (The car will turn it on anyway to protect the battery pack, if it needs to, even if you have Intelligent battery heating turned off). If you're able to preheat whilst connected to your home charge point then it doesn't hurt to do it as this shouldn't impact range due to the charge point replacing any energy used for the heating.

 

[GhostOfClayton]

Your LR battery is less impacted by cold weather than the LFP pack in the SR car, so don't worry about it. Even in my SE SR I've rarely used battery heating. (The car will turn it on anyway to protect the battery pack, if it needs to, even if you have Intelligent battery heating turned off).

Any thoughts about the Xpower battery pack?

 

[siteguru]

Xpower = LR battery pack. Even the ER uses the same chemistry as the LR, just more of it. The SR is the "odd one out" in the range.

 

[fnegroni]

Generally I agree, except if you demand 100% from the battery when it's stone cold, especially with the x-power, you might get reduced performance.

You don't need to warm it up for the full 20 minutes / half hour that it normally runs for. Even running the battery heating for say 10 minutes and then let the now hot coolant dissipate the heat throughout the battery pack for another 10/15 minutes would be more than sufficient to get it up to a safe operating temperature above 10C.


Using Car Scanner's experimental MG4 profile, my OBD2 sensor reads the "battery temperaure" sensor giving back two values, alternating every couple of seconds or so between average tempeature of the battery pack and temperature of the coolant going through the battery heater: you can see that within 10 minutes the coolant rises from say 5C to 30C and above, but the battery pack takes twice as long to reach 20C.

 

[Ayoull]

Your LR battery is less impacted by cold weather than the LFP pack in the SR car, so don't worry about it. Even in my SE SR I've rarely used battery heating. (The car will turn it on anyway to protect the battery pack, if it needs to, even if you have Intelligent battery heating turned off). If you're able to preheat whilst connected to your home charge point then it doesn't hurt to do it as this shouldn't impact range due to the charge point replacing any energy used for the heating.

LFP perform better in cold than NMC due to thermal stability.

LFP optimal temp range is 10C - 40C
NMC optimal range is 20C - 40C

NMC appears to perform better is it is more energy dense but loses a higher % of usable power than LFP in studies undertaken, especially below 0C

The disadvantage LFP has is in the cold (below 0C) it is harder to charge due to its thermal stability, where as NMC produces more heat when charging due to a non-rigid crystalline structure, (the lithium is in layers with the other chemicals within the battery construction, where as in LFP the iron and phosphate form a tunnel structure which doesn't move, in NMC it essentially each layer glides over the one below) it warms itself up more while charging.

The benefit of the heat production in NMC is negated in use of power or driving the car because it is pure waste product opposed to useable energy, the benefit in charging while energy is wasted it improves the charge speed over LFP.

 

[CarbonEV]

Wanted to ask what the use case was for switching on Battery Heating?

What does “Long Trip Mode” do?

 

[siteguru]

Long Trip Mode allows the car to charge to 100%. The alternative is Health Mode (any target 80% or lower).

Battery heating does what it says on the tin - heats the main battery so that it a) works more efficiently, and b) allows faster charging from a DC rapid. However it uses battery charge to do the heating, so it's only really of benefit if you can use it whilst you're charging the car. An alternative is to switch on Intelligent (?) battery Heating in the car but for most people the charge it uses isn't worth the loss of overall efficiency.

 

[fnegroni]

Long Trip Mode allows the car to charge to 100%. The alternative is Health Mode (any target 80% or lower).

Battery heating does what it says on the tin - heats the main battery so that it a) works more efficiently, and b) allows faster charging from a DC rapid. However it uses battery charge to do the heating, so it's only really of benefit if you can use it whilst you're charging the car. An alternative is to switch on Intelligent (?) battery Heating in the car but for most people the charge it uses isn't worth the loss of overall efficiency.

Not entirely true: if I charge the battery at night or during the day at the lower rate, come morning I can use the lower rate charge in the battery at the expense of a minute reduction in overall range.
Bearing in mind most of the time people charge well before they get to below 10% SoC, even if you lose 4% of battery charge, you can just stop a few miles later than intended to charge from say 6% instead of 10%.
Once the battery is warmed up it takes a long time for it to cool down enough to require a full heating session.
and if you combine the slightly higher efficiency, it’s just a matter of whether one intends to preserve battery life at the expense of a two to four kWh per day.

 

[Martinonline]

You have introduced 'battery life' into the discussion about 'battery heating'. Please expand on this in regard to battery heating.

 

[CarbonEV]

Long Trip Mode allows the car to charge to 100%. The alternative is Health Mode (any target 80% or lower).

Battery heating does what it says on the tin - heats the main battery so that it a) works more efficiently, and b) allows faster charging from a DC rapid. However it uses battery charge to do the heating, so it's only really of benefit if you can use it whilst you're charging the car. An alternative is to switch on Intelligent (?) battery Heating in the car but for most people the charge it uses isn't worth the loss of overall efficiency.

I’m guessing I’m in long trip mode since I charged to 100%?

 

[fnegroni]

You have introduced 'battery life' into the discussion about 'battery heating'. Please expand on this in regard to battery heating.

To maintain the battery within the recommended operating range, one can use the battery heater to ensure the battery isn’t operated at cold temperatures that are lower than recommended.
If it’s -5°C outside, heating the battery to be at between 0 and 10 degrees before driving can ensure a safe operating temperature.
Obviously this doesn’t apply to storing the battery. The colder the better.
But while operating the battery it’s best to avoid for it to be below zero, and if you are asking its full performance it’s best for it to be at near ‘laboratory ambient temperature’ which is around 20°C.
Again, this option in the app allows you run the battery heater just long enough to make the battery just warm enough without using too much energy.
It’s true the BMS will intervene, but it can’t predict (yet) your usage pattern.
For example, I opened a thread where trying to charge the battery to 100% at 0°C (in my case an LFP battery) took excruciatingly long using a granny charger because the BMS decided it needed to heat the battery while charging as it reached 96%. This was to prevent damaging it.
Heating the battery before charging it proved to be more efficient.

 

[Torryhun]

To maintain the battery within the recommended operating range, one can use the battery heater to ensure the battery isn’t operated at cold temperatures that are lower than recommended.
If it’s -5C outside, heating the battery to be at between 0 and 10 degrees before driving can ensure a safe operating temperature.
Obviously this doesn’t apply to storing the battery. The colder the better.
But while operating the battery it’s best to avoid for it to be below zero, and if you are asking its full performance it’s best for it to be at near ‘laboratory ambient temperature’ which is around 20C
Again, this option in the app allows you run the battery heater just long enough to make the battery just warm enough without using too much energy.
It’s true the BMS will intervene, but it can’t predict (yet) your usage pattern.
For example, I opened a thread where trying to charge the battery to 100% at 0C (in my case an LFP battery) took excruciatingly long using a granny charger because the BMS decided it needed to heat the battery while charging as it reached 96%. This was to prevent damaging it.
Heating the battery before charging it proved to be more efficient.

Surely there's nothing unsafe about using the car how ever cold it is, pre heating is about efficiently getting the best out of your Soc for your required journey

 

[Coulomb]

Surely there's nothing unsafe about using the car how ever cold it is,

LFP cells can be damaged by charging them below 0°C, I believe, due to a thing called "lithium plating". But I imagine you could drive it just fine, just not have any (significant) regen.

 

[tsedge]

Interesting, I have wondered if I'd be better off pre-heating the battery in winter.

There's no question of anything being unsafe. More about long-term lifespan - if you baby your battery it will last longer - but this only really matters if you are keeping the car for a huge mileage and/or many years.