COLD: No charging today

  • Thread starter Thread starter hobbit
  • Start date Start date
  • Replies Replies 16
  • Views Views 2K
hobbit

hobbit

Well-Known Member
After the car cold-soaked in about -10F air last night, I went out this morning
to take a few stats and see if the car was actually okay. I had designs on
driving two hours to an event today, but figured that was off the table because
it would need at least one charging stop and at the "arctic blast" temps we're
having this weekend, that would just be battery abuse.

coldmorn.webp

The OBD2 kinda confirmed that. The BMS returns two figures for "maximum
discharge power" and "maximum charge power", which I display as "Dis" and
"Cha" respectively. And lookie that: I couldn't charge at any more than 14
kilowatts, if that much, and even a bit of driving would probably not help that
much. So going anywhere significant today was off the table. [I didn't really
need to anyway, and tomorrow might be warmer]

But I did fire up and took a quick store run. The graph is the drive out of
the neighborhood. Under modest load, cell voltage sag was much more than I'd
seen in the past -- that red-n-green line barely wiggles under normal
circumstances. And my regen was severely limited, a little over 30 amps which
is about 10 kW, or one "blue bar" down on the car's display.

When I returned home, about two miles total, "Cha" had gone up to 15. Meh..

I explain the cold-weather difficulties to non-EV people as to envision trying
to pump gas when their fuel inlet pipe has shrunk to a 2mm capillary tube.

_H*
 
hobbit said:
After the car cold-soaked in about -10F air last night, I went out this morning
to take a few stats and see if the car was actually okay. I had designs on
driving two hours to an event today, but figured that was off the table because
it would need at least one charging stop and at the "arctic blast" temps we're
having this weekend, that would just be battery abuse.

View attachment 19706

The OBD2 kinda confirmed that. The BMS returns two figures for "maximum
discharge power" and "maximum charge power", which I display as "Dis" and
"Cha" respectively. And lookie that: I couldn't charge at any more than 14
kilowatts, if that much, and even a bit of driving would probably not help that
much. So going anywhere significant today was off the table. [I didn't really
need to anyway, and tomorrow might be warmer]

But I did fire up and took a quick store run. The graph is the drive out of
the neighborhood. Under modest load, cell voltage sag was much more than I'd
seen in the past -- that red-n-green line barely wiggles under normal
circumstances. And my regen was severely limited, a little over 30 amps which
is about 10 kW, or one "blue bar" down on the car's display.

When I returned home, about two miles total, "Cha" had gone up to 15. Meh..

I explain the cold-weather difficulties to non-EV people as to envision trying
to pump gas when their fuel inlet pipe has shrunk to a 2mm capillary tube.

_H*
Click to expand...

When you charge to 100%, the batterie heater turn on if battey temp is under 8 DegC. It heats up the battery to 10 DegC. The SoC where the activation occurs depends on battery temperature, ie: with battery min temp around -10C, activation will be around 85% SoC. See attached graph that I produced from my obd2 data.battey heater activation.webp

If you program the end of the recharge within an hour before you leave for a trip, you will maintain the battery to at least 10C and get good recharge power on DC charger.
 
For some reason the heat pump and the battery heater seem to be supplied as a pair option-wise, yet I can't see any logical reason why. No-doubt it's up to each importer to decide what options to offer in their market to be competitive and it's possible those who make that decision are unlikely to fully appreciate the benefits. At the very least they should have made the battery heater a dealer-installed option as it looks simple enough. I would have not bought my Kona in 2018 had it not been equipped with a heat pump, as it was a must-have feature in my first-time EV buyer's idealistic mind, but I had no idea that a battery heater was included and could be useful as well.

Because our first shipments were Irish EU-spec cars due to the initial lack of an AU/NZ configuration, our importer had to take them as-built and that is likely why we have these items despite our mild climate. We also have the indicator stalk on the left (noting it's a RHD car), dashboard headlight level adjuster and a rear fog light, all items not always found in this market. There is no BlueLink although I think the hardware is present.

I'm seeing the battery heater frequently switch on at the start of DC charging, even in summer. It causes an offset in the accumulated energy curves between what the charger supplies and what the battery receives. Here it appears to be starting at 18°C then switching off soon afterwards at 20°C during a 36% to 56% charge.

DC charging efficiency test 1 -sm.webp
 
I experienced cold charging last Friday, which went pretty fine. I had a long trip planned, started with a 95% full battery at -20C (temp
of the battery. Air temperature was -28). The battery warmed up pretty quickly, reaching -5C after an hour of driving. "Winter mode" was NOT activated. Cabin heating was pulling 6kW, and engine power about 18, average of 24kW over that hour. Pretty high... But that current draw seems to have warmed the battery very well.

I had to stop for a charge after two hours of driving as I would have made it to my destination with only a few % left. Pretty scary in those cold conditions. Battery was at 5C by that time and it charged at 24kW, reaching 45kW later on when it had warmed up even more.

Key takeaway here: even at -30C, starting with a full battery and driving until 10-20% left will warm the battery enough so that fast charging is possible. I must say I did not expect this. I thought that by that cold, the battery would stay below freezing and "fast" charging would have been pretty slow. Remainder: Winter mode was not activated. I had 0% energy usage from "battery care". In this case, I feel winter mode would have unnecessarily eaten some kWh if it would have started heating the battery when it went below 30%.




Envoyé de mon iPhone en utilisant Inside EVs
 
herode10 said:
My experience on DC charger, the heater runs for 15-20 minutes max if the battery temp is under 25 degC. Without heater, except for a few weeks in summer where ambiant temp is over 25 degC, I would never see 75kW.
View attachment 19715
Click to expand...
With our pack chemistry things certainly get better (charging wise included) once that magic 20 degree ambient is achieved providing a positive curve. Thanks for the info, I had not realized the battery heater actually came on at such high temps .
 
I see about 3.5 kW when the PTC runs for a few minutes starting off under 7 deg C. I recall reading somewhere that it’s rated at 5.5 kW.
 
O Daigle said:
I experienced cold charging last Friday, which went pretty fine. I had a long trip planned, started with a 95% full battery at -20C (temp
of the battery. Air temperature was -28). The battery warmed up pretty quickly, reaching -5C after an hour of driving. "Winter mode" was NOT activated. Cabin heating was pulling 6kW, and engine power about 18, average of 24kW over that hour. Pretty high... But that current draw seems to have warmed the battery very well.

I had to stop for a charge after two hours of driving as I would have made it to my destination with only a few % left. Pretty scary in those cold conditions. Battery was at 5C by that time and it charged at 24kW, reaching 45kW later on when it had warmed up even more.

Key takeaway here: even at -30C, starting with a full battery and driving until 10-20% left will warm the battery enough so that fast charging is possible. I must say I did not expect this. I thought that by that cold, the battery would stay below freezing and "fast" charging would have been pretty slow. Remainder: Winter mode was not activated. I had 0% energy usage from "battery care". In this case, I feel winter mode would have unnecessarily eaten some kWh if it would have started heating the battery when it went below 30%.




Envoyé de mon iPhone en utilisant Inside EVs
Click to expand...

I don't know if the extra 2.5kW that the battery care draws may have put you short from reaching the DC charger but you could have charged at 45kW right from the start.

I'm in Montreal too, I went for a 40 minutes drive saturday morning with 80% starting SoC. At -29C ambiant temperature, the coldest battery temperature probe was at -25C. Driven mostly highway at 105km/h; heating was pulling around 6kW as well and engine power over 24kW. Finished with an average of 30 kWh/100km and coldest battery probe at -9C.
 
That option has only been recently available on US models. The older models don't have a battery heater and therefore no winter mode. Canadians have always had it. The UK had it initially but it's no longer standard. Australia never had it, while here in NZ 64kWh models have it as standard but not 39kWh models.
 
KiwiME said:
That option has only been recently available on US models. The older models don't have a battery heater and therefore no winter mode. Canadians have always had it. The UK had it initially but it's no longer standard. Australia never had it, while here in NZ 64kWh models have it as standard but not 39kWh models.
Click to expand...

Once per eon it seems that us Canadians get something the rest of the world doesn't. Battery heater it is, and heat pump. We'll have to wait for the next eon for something else.
 
It's actually not surprising that the battery heater [if so equipped] might run for a bit at the start of
DC fast charge. I always got my highest power when the battery was just shy of 100F, that seems
to be its happy place. In fact the number of times I checked the OBD2 and saw it right at 98.6 F
was kind of disturbing. [That's "normal" human body temp for y'all Celsius fans]

_H*
 
You must log in or register to reply here.
Back
Top