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Discussion Starter #1
Here in Minnesota we've had a snap of cold temperatures and then a snowstorm/turned blizzard. I decided, since I own a Jeep Wrangler, to use that vehicle for the past week. Since I did not want to leave my 500e sitting at 100% charge for several days, I did not charge it after its last use. I parked it in the driveway at 83% charge. Today, a few days later, I checked the charge and it was only 52%. Normally the car holds charge. My thought was several days ago the temperature dropped to -14F in the morning. Perhaps the car came out of hibernation and heated the battery pack? Does the car do this in extreme low temperatures? So... something to be aware of is to check the car often if not plugged in and the temperature gets extremely cold.
 

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I could be wrong, but the car does try and regulate the battery system at all time. You can verify this through the alpha obd scan. Since you know how cold it got and for what duration, you can compare that to the total time that your battery system had been at that temperature. So let's say the weather got to - 14F for 12 hours, but your battery system only went down to that level for 5 minutes then you know that the car was actively warming the system.
 

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95% sure the car won't heat the battery while unplugged and off. Batteries are perfectly fine being cold while not in use. It could be just that a certain part of the battery is still too cold and is still unavailable. So you should see it come back as you use the car.
 

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Discussion Starter #4
95% sure the car won't heat the battery while unplugged and off. Batteries are perfectly fine being cold while not in use. It could be just that a certain part of the battery is still too cold and is still unavailable. So you should see it come back as you use the car.
Don’t think that is the case. I simply plugged it in for a few hours and brought the car up to 87% charge in its normal charge rate. I’ve never seen this before. Today it was warmer. It seems like something actually drained the battery when it was bitter cold. Wondering if any other cold climate users have ever seen this happen.
 

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This made me wonder why we lose range when cold (even without HVAC). Is it maybe due to voltage dropping? So I checked my phone's Li-ion voltage, turned it off, stuck it in the freezer for a while, then turned it back on again to check cold voltage:

10:23pm 72.5F 3.926V
10:59pm 28.9F 3.517V!!!
10:59pm 32.4F 3.650V
11:17pm 65.3F 3.843V

That's a pretty big difference, considering that 3.9 is around 60% & 4.2 is 100%

Strangely though, the % gauge didn't change much, & actually went UP in the middle: 61%, 62%, 62%, & finally 60%, respectively, but our 500e gauge might be more closely linked to voltage than my phone's "AccuBattery" app.
 

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If you read the battery with the AlfaOBD you can see a setting called
"Periodic Wakeup (Vehicle Wake up) WakeUps 1 to 3:
Life time numberof Wakeups: ##
Life time number of Charge needed wake ups: #
Life time number of Cooling needed wake ups: #
Life time number of heating needed wake ups: #
Life time number of Balancing needed wake ups: ##"

I believe this is where you can see if your car decided to use battery to heat the battery.
My car shows 0 wakeups for heating needed, and I know it's spent at least 3 years in Utah (though the owner before me had a garage, so its unlikely it actually saw cold temps during his ownership) I do not keep it in a garage, so it sees ambient Salt Lake temperatures.
 

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This made me wonder why we lose range when cold (even without HVAC). Is it maybe due to voltage dropping? So I checked my phone's Li-ion voltage, turned it off, stuck it in the freezer for a while, then turned it back on again to check cold voltage:

10:23pm 72.5F 3.926V
10:59pm 28.9F 3.517V!!!
10:59pm 32.4F 3.650V
11:17pm 65.3F 3.843V

That's a pretty big difference, considering that 3.9 is around 60% & 4.2 is 100%

Strangely though, the % gauge didn't change much, & actually went UP in the middle: 61%, 62%, 62%, & finally 60%, respectively, but our 500e gauge might be more closely linked to voltage than my phone's "AccuBattery" app.
Yes this is what I would expect. And I see it on both of our electric cars everyday when there’s a significant temp change. Driving from hot to cold the usage seems to increase, but you regain it back driving from cold to warm.
 

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Discussion Starter #8
Periodic Wakeup (Vehicle Wake up) Wake Ups 1 to 3:
Life time number of Wake ups: 22
Life time number of Charge needed wake ups: 0
Life time number of Cooling needed Wake ups: 0
Life time number of heating needed Wake ups: 0
Life time number of Balancing needed wake ups: 22
Life time number of 12 volts charging needed wake ups: 0
Number of BPCM wakeups between vehicle wake ups: 1326
Longest Time since last wake: 57841 sec
Lowest Max Cell Voltage: 4098 mV
Highest Max Temp: 4 Deg.C
Lowest Min Temp: -9 Deg.C
Largest Cell voltage Differential: 0 mV
Lowest 12 volts: 12.00 V

Just grabbed my latest values a few minutes ago. Doesn't look like the car woke up for heating. I noticed that the Balancing wakeups have incremented regularly since I've owned the car. Odd, as my first reading, shortly after purchasing the car shows Wake ups as 0. I can't believe that it would be zero, as the car was 3 years old when I purchased it.

Lowest temperature recorded is:
Top 5 lowest Module Temperatures:
Min EEPROM 1st lowest: -20 Deg.C
Min 1st lowest: 10
Min EEPROM 2nd lowest: -19 Deg.C
Min 2nd lowest: 7
Min EEPROM 3rd lowest: -19 Deg.C
Min 3rd lowest: 8
Min EEPROM 4th lowest: -19 Deg.C
Min 4th lowest: 18
Min EEPROM 5th lowest: -19 Deg.C
Min 5th lowest: 9
 

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Speaking of "odd" OBD readings, when I checked my 2013 in 2019, after it was about 6 years old & I had personally driven it nearly 4 years, it showed a total of only 251 days (less than a year) at all states of charge, temperatures, & currents (which includes zero, when parked). In other words, OBD does NOT seem to include everything in the car's history.

I also can't believe its current HV batt State Of Health reading of "100.00 %" after over 6 years & 24,000 miles, or even its SOH-C reading of "99.22 %".

I'm away from my car for a few days, but I'm pretty sure AlfaOBD shows some minimum (& max) temps for "Emergency", "Alarm", & "Warn". It definitely does for voltage: "Emergency" at 1.999V & 4.2V, "Alarm" & "Warn" both at 2.699V & 4.15V. I think the low temp is VERY low.

As to the exact subject line, since it appears that batt heat wasn't activated, it seems that cold temperature caused NO sudden hv battery discharge. Just a temporary voltage loss, which is apparently normal for a Li-ion battery.
 

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Don’t think that is the case. I simply plugged it in for a few hours and brought the car up to 87% charge in its normal charge rate.
And what temperature was it when you plugged it in? Lithium ion batteries do not charge below freezing point, 32 degrees F. It would require heating back up, which takes time. And actually, heating the battery at any temperature increases voltage. Electrons move slower at lower temperatures and faster at warmer temps which affects voltage readings.

Which is probably why some people pre-condition the battery in cold weather- since doing so heats it up, increasing the voltage, and providing more available charge.

Also, your car may indicate it is charging after plugging-in at below freezing temperatures. But the li-ion battery can't charge until it is warmed-up enough for the temperature to go above freezing first.
 

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Discussion Starter #11
It was 10F when I plugged it in. I kept an eye on it from time to time over the 3 hours. I actually was expecting no increase in percent charge for a while (expecting a warm up time), but it did appear to start increasing in percent charge shortly after plugging in, which I thought was odd as well. Yeah, I have read that Lithium batteries should not be charged below 32F and should not be discharged when colder than -40F. That the BMS systems need to warm the batteries to at least 32F before charging.
 

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It’s not that Lipoly can’t be charged below freezing temperatures but one problem is that the accuracy of voltage based algorithms to determine SOC suffers. For example charge to 4.2V at super cold temps and in many instances watch the voltage rise as the cell temperature increases. If it’s already at 4.2V/cell cold what will voltage reach warm? Dangerous game to play.

In their wisdom, Fiat/Bosch uses 4.1V/cell 100% SOC which is always a good buffer for this and many other conditions.

Yes, charging below 32F plating of metallic lithium is another concern but that’s more of an issue with consumer lithium batteries.

With varying degrees of success, commercial lithium batteries employ special additives and lower charge current schemes to help mitigate irreversible damage of charging below 32F.

But even with commercial SDI cells and excellent 500e thermal management if someone needed to charge much below stone cold 15F I would probably pull 10-30kW motor load for a few seconds to somewhat warm the cells inside-out before applying charge current.

500e thermal management takes care of many problems but it can only work from the outside of the cell housing inward. Internal warming will occur from charge current but it risks metallic lithium plating while it’s a much smaller influence than a momentary high amp motor load.
 

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Discussion Starter #13
The mystery continues. The 500e is parked in my driveway and has not been driven in over a week. A couple of days ago I reported the sudden apparent loss in charge according to the dash charge indicator. Two days ago I charged it up to 87% and unplugged it. Tonight, two days later, it again has dropped in in apparent charge level (pictures below). So at some point it went from 87% to 58%, a loss of 29%. So, again, tonight I plugged it in for 3 hours at about 240V @ 15Amps current. Chargepoint shows 10.9 kWh. It is also throwing the Guess O Meter for a loop as well.
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If that was happening to me, I would be strongly tempted to see if a system reboot via 12V disconnect made any difference. It almost certainly wouldn't hurt.
 

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I'm finally able to report my own car's OBD readings, to compare to Abe's in post #8 above, & it shows zero wake ups for any of the listed reasons, but it also shows some very strange numbers for voltage & temp (except for "Lowest 12 volts", for which zero makes sense due to my reboot via 12V disconnect):

Periodic Wakeup (Vehicle Wake up) Wake Ups 1 to 3:
Life time number of Wake ups: 0
...
Number of BPCM wakeups between vehicle wake ups: 846
Longest Time since last wake: 0 sec
Lowest Max Cell Voltage: 0 mV
Highest Max Temp: -40 Deg.C
Lowest Min Temp: -40 Deg.C
Largest Cell voltage Differential: 0 mV
Lowest 12 volts: 0.00 V

The following readouts seem realistic, here in SoCal where it rarely approaches freezing. I once saw some sort of icy road warning, I think at around 37F.

Lowest temperature recorded is:
Top 5 lowest Module Temperatures:
Min EEPROM 1st lowest: 8 Deg.C
Min 1st lowest: 7
Min EEPROM 2nd lowest: 8 Deg.C
Min 2nd lowest: 8
Min EEPROM 3rd lowest: 8 Deg.C
Min 3rd lowest: 10
Min EEPROM 4th lowest: 8 Deg.C
Min 4th lowest: 9
Min EEPROM 5th lowest: 9 Deg.C
Min 5th lowest: 2

I also found this:

Threshold Cals (Module Temperature):
Temperature Under Temperature Emergency: -46 Deg.C
Temperature Under Temperature Alarm: -45 Deg.C
Temperature Under Temperature Warning: -45 Deg.C

With no warning even occurring above -45 Deg.C, it would seem that in this case the original post's -14F (-26C) is nowhere near cold enough to require mandatory emergency battery heat while unplugged.
 

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I'm re-reading Abe's last report & remembering my cell-in-freezer test with drastic voltage loss. I'd like to know the BATTERY temperature when it was charged to 87%, to compare to the 15F ambient temp showing at 58%.

Even though my phone's % gauge barely changed with the huge voltage drop, it seems reasonable to suspect that its recently-updated app might be just a bit smarter than a 500e which might not have had that portion of the software updated since the first one was made in 2013. There must be a formula or chart somewhere that gives voltage drop per degree of temperature change, & like I noted above, a very slight voltage change is significant due to the tiny voltage difference between full & dead.

Even without the battery's heater, charging warms the battery just due to the electrical current flow. Unplugging to stop that flow in cold weather will let the battery cool, & we now know that makes the voltage drop from when it was being warmed by charging. How much drop would depend on how cold it was when charging, & when unplugged.

If you left it plugged in, after it auto-stops, the battery would cool, making the voltage drop, so the charger should come back on. Depending on the temperature, it might cycle on & off a few times until it reached 4.1V even with the battery at ambient temperature. That built-in limit of 4.1V is around 85-90% of the true capacity, so "sitting at 100% charge for several days" isn't really happening, unless after the charger cuts off the ambient temperature warms so much that voltage goes all the way up to 4.2 (equivalent to about 110 or 115% on the gauge).
 

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The mystery continues. The 500e is parked in my driveway and has not been driven in over a week. A couple of days ago I reported the sudden apparent loss in charge according to the dash charge indicator. Two days ago I charged it up to 87% and unplugged it. Tonight, two days later, it again has dropped in in apparent charge level (pictures below). So at some point it went from 87% to 58%, a loss of 29%. So, again, tonight I plugged it in for 3 hours at about 240V @ 15Amps current. Chargepoint shows 10.9 kWh. It is also throwing the Guess O Meter for a loop as well.
View attachment 108277

View attachment 108275
View attachment 108276
Either bms is doing weird things, potentially dangerous, or the car is burning the energy unexpectedly. Have you driven it any? Does it make any noises of pumps running? Maybe point a temp gun and see if anything is warm?
 

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If the pumps happen to be off when you listen, & you don't have a heat gun, you could check OBD for above-ambient temps in the battery, due to current flow.

EDIT: On second thought, the below part of my original post probably isn't right, or else we'd see the % gauge going up & down with every 3 degrees F ! Unless maybe there's software to prevent that, for which maybe Abe's has now failed & needs a reboot. Here's what I had written:

In Abe's last report above, it seems to me* that the % drop in the gauge reading MIGHT be just from temperature drop, IF charging it to 87% caused the battery to warm to 78F (25.5C on OBD)

*Please check my "ball-park" math:

  • 100% on the gauge shows 4109mV in my highest cell on OBD.
  • At 29% (71% lower) it shows 3806 mV (303mV lower).
  • 303mV divided by 71 is only 4.3mV for each percentage point on the Fiat gauge.
- When I froze my phone (post # 5 above) it lost 9.4mV per degree Farenheit, divided by 4.3 would be only 2.2F for each % point on a Fiat gauge.

Abe's 29% gauge drop, times 2.2F per %, is 64F temp change, plus the 14F shown on Abe's gauge would require 78F batt temp when unplugged.
 

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The mystery continues. The 500e is parked in my driveway and has not been driven in over a week. A couple of days ago I reported the sudden apparent loss in charge according to the dash charge indicator. Two days ago I charged it up to 87% and unplugged it. Tonight, two days later, it again has dropped in in apparent charge level (pictures below). So at some point it went from 87% to 58%, a loss of 29%. So, again, tonight I plugged it in for 3 hours at about 240V @ 15Amps current. Chargepoint shows 10.9 kWh. It is also throwing the Guess O Meter for a loop as well.
Regardless, Fiat's recommendation is to keep the car plugged-in during below freezing weather so the BMS can condition the battery charge and maintain temperature. The pic says it is 14 degrees F outside. I wouldn't expect meters to report correct information at below freezing temps regardless and it's clearly an after-effect of operating with a frozen battery as I've never seen anything like that in my climate. I would follow the manufacturer advice and leave it plugged-in during cold weather.

Is it possible 10.9kWh could have been used to reheat the frozen battery at 18 degrees below freezing? I wouldn't be surprised.
 

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Here in Minnesota we've had a snap of cold temperatures and then a snowstorm/turned blizzard. I decided, since I own a Jeep Wrangler, to use that vehicle for the past week. Since I did not want to leave my 500e sitting at 100% charge for several days, I did not charge it after its last use. I parked it in the driveway at 83% charge. Today, a few days later, I checked the charge and it was only 52%. Normally the car holds charge. My thought was several days ago the temperature dropped to -14F in the morning. Perhaps the car came out of hibernation and heated the battery pack? Does the car do this in extreme low temperatures? So... something to be aware of is to check the car often if not plugged in and the temperature gets extremely cold.
I live in Minneapolis as well, and I've never seem my 500e do this. I use a Juicebox charger and do not recall seeing the car begin consuming electricity to warm the battery in cold temperatures overnight either. (Only if I activate pre-conditioning via the my500e app.)

The only time I see the battery take a significant drop is around 40%, and then as I continue to drive it drops quickly, sometimes as much as 20%-25%. From other forum feedback, this means it's time to calibrate my battery by doing a complete discharge followed by a full uninterrupted charge to 100%, which I haven't done yet.
 
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