Low state of charge and cold effect

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apu

apu

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Curious if anybody has had an opportunity to run their Kona to a low SOC in cold temperature since most recent BMS update/recall ? I had an "interesting" experience the other night. I was coming home from a long highway trip with more head wind than usual. It was -12C ambient and I hit turtle mode at 7% SOC when in past it's typically been at 5%. I didn't worry too much as I only had a few more kms to home. At indicated 5% GOM mileage count disappeared as normal and I will guestimate at roughly 3-4% SOC I got fairly severe power reduction to 3kw (vs 150kw at full charge). 3 kw is roughly 4 hp and honestly I was barely getting out of my own way. It was seriously worried I wound not make it the last km. Just curious if this is just the winter effect on the battery or did the firmware reallocate space at the bottom end of the battery's capacity?
 
apu said:
At indicated 5% GOM mileage count disappeared as normal and I will guestimate at roughly 3-4% SOC I got fairly severe power reduction to 3kw (vs 150kw at full charge). 3 kw is roughly 4 hp and honestly I was barely getting out of my own way. It was seriously worried I wound not make it the last km.
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Apu, that is very interesting -- I have not had that experience, but my only turtle mode adventures were in warmer weather. I would not have guessed Hyundai would have bothered to give the car a power mode that slow. I'm glad, because you never know when you might need to shift the car across the charging plaza at 1% SOC. Just surprising. Thanks for the report.
 
apu said:
Curious if anybody has had an opportunity to run their Kona to a low SOC in cold temperature since most recent BMS update/recall ? I had an "interesting" experience the other night. I was coming home from a long highway trip with more head wind than usual. It was -12C ambient and I hit turtle mode at 7% SOC when in past it's typically been at 5%. I didn't worry too much as I only had a few more kms to home. At indicated 5% GOM mileage count disappeared as normal and I will guestimate at roughly 3-4% SOC I got fairly severe power reduction to 3kw (vs 150kw at full charge). 3 kw is roughly 4 hp and honestly I was barely getting out of my own way. It was seriously worried I wound not make it the last km. Just curious if this is just the winter effect on the battery or did the firmware reallocate space at the bottom end of the battery's capacity?
Click to expand...
Sounds like the BMS is doing what it supposed to conform with the spec'd discharge power for the voltage limit of 2.5 V, (can be observed in the LG-E63 cell discussion thread @ 4.4 - power limit specification)
https://insideevsforum.com/community/index.php?threads/lg-chem-lg-e63-cell-discussion.9783/
What was the minimum cell voltage at the 7% level - if you were running TP?
 
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eastpole said:
Apu, that is very interesting -- I have not had that experience, but my only turtle mode adventures were in warmer weather. I would not have guessed Hyundai would have bothered to give the car a power mode that slow. I'm glad, because you never know when you might need to shift the car across the charging plaza at 1% SOC. Just surprising. Thanks for the report.
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I have not been that low or even close, and cold weather here is probably not what most living in other areas would call it, but just the same; I would expect the power reducing to occur at a slightly lower SOC in warm ambient conditions given the specification limits of the cells themselves.
 
apu said:
Yes I believe it was. It could have very well been a factor but I don't think it was quite cold enough. I did not have torque pro logging so I can't completely rule it out.
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Curious what low SOC percentage (cars display not BMS) the 2.5kW heater cuts out to save what energy remains.
apu if you do this again (with the appropriate low temperatures to make the pack warmer come on) , can you check on the cars center display the electricity consumption menu/battery to see when the battery care energy draw reduces to 0 (or what ever value)? (if not I guess TP would be close)
The user manual (2021 model) on page H13 states "Note that the EV battery coolant heater will not be used when the EV battery SOC is low"
Does not give a percentage. I suspect probably at the first warning ~ 10% ?
 
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electriceddy said:
Curious what low SOC percentage (cars display not BMS) the 2.5kW heater cuts out to save what energy remains.
apu if you do this again (with the appropriate low temperatures to make the pack warmer come on) , can you check on the cars center display the electricity consumption menu/battery to see when the battery care energy draw reduces to 0 (or what ever value)? (if not I guess TP would be close)
The user manual (2021 model) on page H13 states "Note that the EV battery coolant heater will not be used when the EV battery SOC is low"
Does not give a percentage. I suspect probably at the first warning ~ 10% ?
Click to expand...
I don't typically let the car see the bottom of battery pack but I will for sure be more attentive next time(hopefully much closer to home and with a little less panic). Honestly I don't think I have ever seen the battery care icon display heater consumption while I have been driving it in winter. I have been able to appreciate when the battery heater has engaged from Torque pro but its usually happens overnight in -20C or less ambient temperature, while the car has been motionless for several hours or while DC charging.

I suspect the chemical activity from driving and any transferred cabin heat never really lets the battery pack get to the approximate -17C battery heater set point even when ambient temperatures are much colder and in motion.
 
Got a chance to repeat the experiment. This time ambient was -2C and battery temp was 10C. I got low battery warning at 8% SOC and then turtle mode at 5% but this time max available power stayed above 20 Kw even down to 1% SOC when I pulled the plug on the fun and games.
Interesting discovery around 3-4% the car turned off the heat as a battery preservation feature and there is no way to turn it back on. Fan speed still functions. Although I hade winter mode tuned off I suspect the battery heater can't be turned on when the SOC is very low. All the 12V powered items still function fine.

The highway trip today actually measured 330 km for 100% charge with consumption at 201 watts/km, my starting BMS reading at 100% was actually 96.5%, So my math 330km x .201 kw/km(actual consumption) x.965 = an available 64Kw, exactly where it should be.
So it looks like that severe power loss I experienced earlier this week was because a cold soaked battery and not the new firmware stealing capacity as I had feared.
 
I noticed when SOC is less then 20% max power is limited to 50kw and when low battery warning is on max power is 20kw when SOC is 2% max power is 5kw. But all of these limitations are not indicated in manual. I guess they are set by BMS. The manual just says when low battery warning is on the battery power is limited but not mention even before the low battery warning is on the battery power is limited already.


Sent from my iPhone using Inside EVs
 
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