Battery drain (10%-3% overnight) ?

[frb123]

So... Completed another long journey cross country yesterday. Arrived with 10% battery and 20 or 21 estimated GOM miles (in Normal). Ambient temp I would guess at 10-12 degrees. Had nailed it, arriving with 10%, or so I thought! Surely a reasonable buffer to aim for?

Intended to get up this morning and charge nearby as my destination didn't have private charging. Ambient temp 8 degrees.

To my horror as per the title it had dropped from 10% to 3%, displaying --- on the GOM (and 6 miles on the battery screen).

This seemed like a sheer drop.
I would expect small fluctuations (ambient temp, battery temp, general weather etc) but this seems extreme - would you agree?

The first chargers I went to we're both in use ? and the second, thankfully, available. They were both within 0.5 miles or so, so no drama in that regard. But it was an unpleasant moment for sure!

Comments/thoughts/suggestions as to cause / future "remedy" (or how to avoid!) welcome!

 

[N2STY]

After a long journey your batteries are warm so in the the morning there cold so that would explain the drop

 

[Lovemyev]

What model are you driving, has it got the LFP battery ?.

 

[DB Go Rex]

This is why I try to find somewhere to charge before setting off the morning after (if there is no destination charging).

E.g. drop the wife and kids off at the hotel and then drive to the charger and leave it there for 45 mins before returning for the evening.

 

[frb123]

After a long journey your batteries are warm so in the the morning there cold so that would explain the drop

Yeah I did think this might be partially to blame albeit was still shocked by the jump.

What model are you driving, has it got the LFP battery ?.

Trophy LR.

**

Oddness continued today... Charged to 60%. Drove over 12 miles ... In this time it went UP to 61% (!) Then started to drop "normally". I'm not overly worried it's just slightly odd and makes for pretty unpredictable behaviour/journey planning etc more random. frustrating to have to build in higher tolerance for journey planning ...

Thinking perhaps balancing might help... I don't know if/when it was last done

 

[Lovemyev]

Trophy LR.

Okay, same as us then, I only asked because the LFP can sometimes struggle to estimate the range correctly, it’s just one of those things with that type of chemistry.
Tesla Bjorn has spotted this behaviour.
Ref your question over balancing ?.
Do you conduct much / any D/C rapid charging by any chance ?.
If the answer is little or never, then balancing frequently on a NMC pack is not a major concern.
Are you charging to the recommended 80% for most of your usage and how often to 100% ?.
How often do you tend to carry out a balance cycle ?.

 

[frb123]

Okay, same as us then, I only asked because the LFP can sometimes struggle to estimate the range correctly, it’s just one of those things with that type of chemistry.
Tesla Bjorn has spotted this behaviour.
Ref your question over balancing ?.
Do you conduct much / any D/C rapid charging by any chance ?.
If the answer is little or never, then balancing frequently on a NMC pack is not a major concern.
Are you charging to the recommended 80% for most of your usage and how often to 100% ?.
How often do you tend to carry out a balance cycle ?.

Sure thing.

So I only got it second hand a week or so ago. Did a rapid charge today and once a week or so ago. Otherwise has been mainly granny. Was charged to 100% when I bought it and 93% when I left home yesterday (miscalculated granny time!?)

I will generally be keeping it to the reccomended 80% and personally haven't carried out a balance yet but intend to soon. Only had it a week or so.

 

[Lovemyev]

Sure thing.

So I only got it second hand a week or so ago. Did a rapid charge today and once a week or so ago. Otherwise has been mainly granny. Was charged to 100% when I bought it and 93% when I left home yesterday (miscalculated granny time!?)

I will generally be keeping it to the reccomended 80% and personally haven't carried out a balance yet but intend to soon. Only had it a week or so.

Aaarh .... so you are a new owner then, welcome !
So as I am sure you know already, that D/C chargers are unable to provide any balancing cycle.
Only 100% A/C charging will provide this facility and you already have one of these already under your belt.
If setting the charge level to 80% suits the majority of your usage patterns, then that is great.
There is a lot of different ideas on the effects of long term battery health of course, but I think we all agree that excessive heat is not a batteries best friend, or running it to a very low SOC on a regular basis either.
Regarding the issue you have seen with regards to fluctuating figures on the GOM.
I have seen slight differences / discrepancies reported by the GOM on both our previous ZS EV Gen 1 and our Gen 2.
Sometimes there will be a slight difference to what the car reports, to what the App reports also.
I have seen us leave home with say ........ 130 miles then 2 miles down the road, it will increase to 132 then drop back a minute latter.
It is either a glitch or it just making it's mind up still ?.
But I found the GOM's on both models to be pretty accurate.

 

[Jomarkh]

Quick question. How many battery types do MG use?
I have a NCM pack and I thought that the NMC was the same thing or is it...
Then there is the LPF is there another one?

 

[frb123]

Aaarh .... so you are a new owner then, welcome !
So as I am sure you know already, that D/C chargers are unable to provide any balancing cycle.
Only 100% A/C charging will provide this facility and you already have one of these already under your belt.
If setting the charge level to 80% suits the majority of your usage patterns, then that is great.
There is a lot of different ideas on the effects of long term battery health of course, but I think we all agree that excessive heat is not a batteries best friend, or running it to a very low SOC on a regular basis either.
Regarding the issue you have seen with regards to fluctuating figures on the GOM.
I have seen slight differences / discrepancies reported by the GOM on both our previous ZS EV Gen 1 and our Gen 2.
Sometimes there will be a slight difference to what the car reports, to what the App reports also.
I have seen us leave home with say ........ 130 miles then 2 miles down the road, it will increase to 132 then drop back a minute latter.
It is either a glitch or it just making it's mind up still ?.
But I found the GOM's on both models to be pretty accurate.

Thankyou! & Good to know

 

[Exdro]

Yeah I did think this might be partially to blame albeit was still shocked by the jump.


Trophy LR.

**

Oddness continued today... Charged to 60%. Drove over 12 miles ... In this time it went UP to 61% (!) Then started to drop "normally". I'm not overly worried it's just slightly odd and makes for pretty unpredictable behaviour/journey planning etc more random. frustrating to have to build in higher tolerance for journey planning ...

Thinking perhaps balancing might help... I don't know if/when it was last done

That’s why it’s called a “Guessometer”?

 

[DB Go Rex]

Quick question. How battery types do MG use?
I have a NCM pack and I thought that the NMC was the same thing or is it...
Then there is the LPF is there another one?

No

 

[drmcw]

No

What about the PLF, CNM, FPL, CMN and MCN?

 

[Stuart Fray]

Was your in-car battery heating set to "on" at any point?

 

[frb123]

That’s why it’s called a “Guessometer”?

Perhaps I'm wrong but my understanding is that the estimated MILES is the GOM.

I had and would expect that if you stopped your journey at 75% displayed, then the next day you'd have the same. Or maybe 74% or whatever. The only reason given (that does make some sense) is battery temp - but it's still an extreme drop IMHO. How are you meant to (confidently) eak out Max range if you can't rely on the battery percentage figure? I suggest you can't..

So you're saying the battery percentage is also a guesstimate rather than accurate capacity readout? (If it can be described that way?) Perhaps I'm drawing too much of behavioural and literal comparison so a petrol tank.

Was your in-car battery heating set to "on" at any point?

Good thought, but no, I didn't even have the ismart app set at this time so nothing occured whatsoever whilst it was parked...

 

[DB Go Rex]

So you're saying the battery percentage is also a guesstimate rather than accurate capacity readout? (If it can be described that way?) Perhaps I'm drawing too much of behavioural and literal comparison so a petrol tank.

Battery percentage is probably less concrete than a fuel tank level, for sure.

It's done on a calibrated voltage drop, and with the complexity of battery chemistry I don't think you can 100% expect it to be a direct comparison.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://batteryuniversity.com/article/bu-903-how-to-measure-state-of-charge&ved=2ahUKEwizjaOK6LL9AhXUQUEAHSbtAoYQFnoECAwQAQ&usg=AOvVaw3JoxdW2CcvDtGQ8HG0NAIv

 

[southsider]

Last week we were on hols in England with the final leg being a 100 mile journey to relatives' house, arriving in their driveway with 10% charge. Unloaded the car and locked it. A few hours later I intended to drive it over to a fast charger but to my horror when I switched the car on it said 0% battery. Thankfully could charge it with the granny charger though it obviously took a while.

Not sure why it dropped to 0%...but word of caution because if I'd driven straight to a charging station at 10% and found the chargers to be in use, I'd have parked up and switched the car off. Now not convinced I'd have been able to get it going again to drive into an EV space...

 

[N2STY]

Last week we were on hols in England with the final leg being a 100 mile journey to relatives' house, arriving in their driveway with 10% charge. Unloaded the car and locked it. A few hours later I intended to drive it over to a fast charger but to my horror when I switched the car on it said 0% battery. Thankfully could charge it with the granny charger though it obviously took a while.

Not sure why it dropped to 0%...but word of caution because if I'd driven straight to a charging station at 10% and found the chargers to be in use, I'd have parked up and switched the car off. Now not convinced I'd have been able to get it going again to drive into an EV space...

It's obviously a temperature drop thing after 100 miles straight the cells will be nice and toasty although this problem is mainly been seen on the standard range

 

[southsider]

It's obviously a temperature drop thing after 100 miles straight the cells will be nice and toasty although this problem is mainly been seen on the standard range

Possible, but I've not seen the same thing at higher SOC. Like finishing a journey at 65% one day...next day it's still at 65%.

 

[frb123]

Possible, but I've not seen the same thing at higher SOC. Like finishing a journey at 65% one day...next day it's still at 65%.

I would echo this.

I guess ultimately for me, it's concerning that you can't "have faith" in the the lower, sub say 15%ish figures. On long journeys (that may, for example be completed in two chunks, one bit being some hours after stopping and subsequent battery cooldown) it's essential imho to be able to stop and have confidence in what's left "in the tank". It's just a bit random for my liking