Traction Battery Cooler Experiments

Discussion in 'Prime Plug-in Charging' started by m8547, Jul 18, 2019.

  1. m8547

    m8547 Active Member

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    I bought an OBD dongle so I could keep an eye on the battery temperature. Keeping the battery cool will help extend its life.

    It was pretty hot today, around 97-101 F. I parked in the sun with the windows open most of the day at work. Before I left I plugged in long enough for the traction battery cooler to run and a few minutes more to make sure I had enough charge to get home (probably 40-45 minutes total). On the way home I ran an errand and parked in the shade.

    When I got home the battery temperature was 102. I parked in the shade, plugged in and let the tractor battery cooler cycle run for the full amount of time (usually 5 minutes waiting plus 30 minutes of air conditioning). I didn't check to make sure it ran the whole time, but the car was cool when I got in, so I think so. The battery temperature was 95 degrees. That's not a very impressive amount of cooling, but on the other hand the battery has a lot of mass.

    I let it charge for two hours on my L1 charger after that. It cooled off slightly outside, and now the battery shows 93 degrees.

    I plan to figure out the threshold temperature for the traction battery cooler message (I think it's about 90 degrees). And I plan to test if the remote AC button on the fob makes any difference in battery temperature (I doubt it's significant). And I might test how much of a difference it makes to drive with the AC on or not.
     
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  2. jb in NE

    jb in NE Senior Member

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    One approach might be to charge the battery early in the morning, just prior to driving it, when the ambient temperature is the coolest. If you drive it home late afternoon/early evening, then let it cool off for as long as possible until you charge it.

    One thing you might note when you do the experiment is the air temperature going to the battery and the fan speed (if your app shows that). I think Hybrid Assistant shows both.
     
  3. m8547

    m8547 Active Member

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    I usually do set a timer to depart at 6am so it charges overnight. But my commute is 30 miles round-trip, so I need to charge some at work and/or when I get home if I want to do any errands on the way home or after I get home. My commute is also quite hilly, so I think the drive heats the battery significantly. So I'm experimenting with charging just long enough to run the traction battery cooler before or after driving to cool off the battery quickly. After I get home I've noticed it doesn't seem to cool off very quickly throughout the evening, but that would be another thing to measure.

    I am using hybrid assistant, but the interface is confusing so I haven't found fan speed or incoming air temperature yet. It shows interior air temperature, is that the same thing?
     
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  4. jb in NE

    jb in NE Senior Member

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    Yes. That is the air going to the battery.
     
  5. m8547

    m8547 Active Member

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    I guess residual "coldness" in the cabin continues to cool the battery for a while as it charges.
     
  6. NSXT

    NSXT Member

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    My traction battery slowed down charging last time due to heat, since that day I ensure AC in my cabin is cool before I park the car back to the garage when I get home (based on forecast).

    And of course "Get Ready to react" with the 5 seconds pop up to enable AC during charging after power off. So far I haven't seen that message when my cabin was cool/freezing :rolleyes:

    My daily charging schedule is usually 3-4 hours cooled down before it kicks in around 7:45pm (when electricity is the cheapest). I usually leave at 6am to work so I have allowed it to cool down a bit after the charging schedule is completed. So far I am ok with that schedule.

    My area temperature with humidex is about 47C/117F today so I will be ready when I get home to meet that pop up :whistle:
     
  7. Salamander_King

    Salamander_King Senior Member

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    Cool experiment. I have seen the battery cooler pop-up message only once in last two years, but looking at the temperate data from Hybrid Assistant, the trigger temp must be higher than 90F. Yesterday at the end of my afternoon commute, the battery temp was shown to be above 90F, but I did not see the pop-up. See graph below.

    Since I don't usually look at the screen of Hybrid Assistant App while I am driving, I am not sure if the real time data is displayed on the screen of the App, but the report generated shows data for "Battery Inhaling Temperature". This temperature is different from "Room Temperature". Yesterday, I had car parked in sun, so the inside room temp was very high initially compared to cool outside ambient temp. Strangely the battery inhaling temp is much lower than room temp initially but higher than ambient temp as shown in the graph below. I think if the ambient temp is lower than cabin temp, the battery fan somehow intakes air from outside.

    temperature.png
     
    #7 Salamander_King, Jul 19, 2019
    Last edited: Jul 19, 2019
  8. jb in NE

    jb in NE Senior Member

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    That was my thought. When I run Hybrid Assistant I rarely look at the screen display. The reports have the real data that you can study at your leisure.

    I don't think this is the case. The air intakes are at the back seat side, and this may just be a cooler location in the car or the sensor might be down inside the air intake tube nearer the battery, which would be under the seat or under the rear deck.

    This is a good post. It's screaming hot here today, so I may make a recycling run and see what Hybrid Assistant shows, even on that short run.

    The last three days after driving 11 miles home after the car sat in the sun at 95F +, I did get the infinitesimally quick battery traction cooler question and answered yes. I don't know if it changed anything, as the car was always at full charge at 0620 the next morning as I had programmed it.
     
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  9. Salamander_King

    Salamander_King Senior Member

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    You might be right. Now looking at the graph again, it is strange to see the data showing initially higher room temp vs lower inhaling temp reversed during my trip around 16:09:11, becoming higher inhaling temp than room temp. If the sensor for the inhaling temp is located near the battery as you suggested, it does explain why the inhaling temp get hotter as the battery works longer while the room temp is getting cooler.
     
  10. Salamander_King

    Salamander_King Senior Member

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    Since our temp rarely gets high, I almost never see the battery cooler pop-up message at the end of a trip. Even if I see the message on some unusually hot day, I am likely to ignore the message for I do the charge over night just like you. Our night temp is always below 70F, and car being outside on my driveway, it is very unlikely there is any need for the battery cooler to operate before or during nightly charging session.
     
  11. Georgina Rudkus

    Georgina Rudkus Senior Member

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  12. jb in NE

    jb in NE Senior Member

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    I don't think this will improve anything. The air directly out of the cooler might be a bit cooler than the cabin temperature, but the waste heat from the cooler goes into the cabin, so you are just adding the electrical energy input to the cooler as overall cabin heat. If the car runs the HVAC system during charging, the waste heat is rejected outside the cabin, which results in net cooling of the cabin.
     
  13. NSXT

    NSXT Member

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    It would be nice if Toyota can add all this type of information into our existing dash panel. Lots of space for that :rolleyes:
     
  14. m8547

    m8547 Active Member

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    I rarely hit the temperature at which charging slows down. I'm not going to test that one, but it's definitely higher than the temperature at which the traction battery cooler message appears.

    The battery doesn't care about humidity, only the actual temperature. But higher humidity does make the AC work harder to cool the cabin, and it might not be able to get it quite as cold. If recirculate is on then the cabin air will dry out, and eventually humidity will have less of an effect.


    I think the temperature is a few degrees above 90. My guess is 93-95. 95F is 35C, so maybe it's that. There might be other required conditions for it to activate, like outside temperature, I don't know. And I suspect that it doesn't always run even if you see the message and say Yes, if the battery cools off a bit after that.
     
  15. ed4271

    ed4271 Member

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    I usually ride with my windows down. I do 48 on the highway on a 55 mile an hour Zone. The reason I leave the windows sounds so I can feel the nice breeze coming into the car which directly will go into the two vents in the back . The air is not hot if it was that we roll up the windows and use the AC. But it doesn't matter if I ride with the AC on or if I ride with the windows down. It's a guessing game when it will ask me about cooling the traction battery when I turn off the car. Sometimes I can ride with the AC on and then drive home and it was say ask me to use the AC to cool the traction battery. Other times when I ride home with the windows open similar temperature inside the car and it doesn't in for me to use the AC it's cool the traction battery.. what I can say is it hit or miss on the temperature of the battery and how much air is circulating and traveling through that battery vent.

    Posted via the PriusChat mobile app.
     
  16. m8547

    m8547 Active Member

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    I noticed today that while the traction battery cooler was running plugged into my L1 charger, the air conditioning compressor was cycling on and off. When I've used it on L2 I thought the compressor runs most (but not all) of the time. So it might be more effective on a L2 charger.

    While it's cooling on a L2 charger it usually uses around 1kwh in about 30 minutes, so obviously a L1 charger can't keep up with that.
     
  17. NSXT

    NSXT Member

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    Last Friday when I got home, my cabin temperature was ICY/AC cool and outside temperature before power off was 31C/88F (habit to get ready to flip and push) finally the pop up display showed up. Looks like it is an outside temperature sensor thing?

    I agree with windows down and let the air comes in will circulate the back vents better even with AC on :rolleyes: (longer battery life). But the pop up display to cool the traction battery during charging could be an outside temperature thing and very inconsistent. Toyota needs to fix this flaw to allow us to choose in the menu and not to guess when to turbo our mind/finger game :ROFLMAO:

    L2 is better and more convenience in every ways but isn't fast charging usually degrades the battery faster compare to slow charging?
     
  18. m8547

    m8547 Active Member

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    Yes, but mainly only because of the heat created by charging. Even L2 is slow as far as the battery is concerned. During regen or charge mode (or DC fast charging in Japan) it will charge at something like 40-60kW (I can't remember the limit).
     
  19. m8547

    m8547 Active Member

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    I experimented with pre-conditioning today. I had about 45% charge remaining, the battery was at 86 degrees. I parked in the sun and plugged into a L2 charger at 2pm. I set the departure time for 2:45pm since I knew that would be before it finished charging. I went back to the car at 2:40, and I could hear the AC running. I waited until it stopped and got in without unplugging. The cabin was cool but very quickly got hot again (since the AC doesn't run in "not ready to drive" mode). The battery fans were running as expected while charging, and the battery temperature was 89 degrees and 80% charged. I don't think any additional cooling would happen after the pre-conditioning stopped since the cabin got warm quickly, and it's not clear how helpful it was at cooling the battery. It's better than nothing, but I suspect maybe not worth the time/electricity to try to cool the battery this way.

    I moved the car back to the shade, and the battery temperature got to 91 degrees on the drive. My battery has rarely been much below 90 degrees in the last month. Even parked overnight without charging it seems to stay in the 80's when the outside temperature is high 60s-low 70s. The battery seems to be somewhat insulated from the outside temperature. When I got in the car around 2pm today it was 90 degrees outside and much hotter inside the car, but the battery was only 86. The car had been in the shade most of the morning. That is surprising because it seems like a lot of the time outside air could help cool the battery. But maybe it is intentional so that in very hot/cold weather the cooling/heating system doesn't have to work as hard to keep the battery conditioned?
     
  20. vvillovv

    vvillovv Active Member

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    Since I don't have access to pack temps currently do you mind if I ask you for some help determining the diff between L1 and L2 charge temps?
    I understand if you don't want to waste 4 or 10 extra hours to do the comparisons (10 extra hours if the charge setting is changes to 8 amps on the MID) just for me or anyone else interested in pack longevity if only to get your take on the difference in L1 and L2 temps in hot charging situations. I only ask as I'm very interested in pack longevity and to get at least one baseline comparison, if you have the time and interest as I do. thanks.
    I get the windows open message in the MID a lot too. :)
     
    #20 vvillovv, Aug 11, 2019
    Last edited: Aug 11, 2019
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