GenII HV Battery Fan cleaning and testing

Discussion in 'Gen 2 Prius Technical Discussion' started by w2co, Jul 30, 2019.

  1. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I was considering running the quick-connect out through the grill, but then had a thought: it's a long shot, but could someone connect the two pins of the quick connect with a jumper wire, short out the battery?
     
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  2. Skibob

    Skibob Senior Member

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    You would blow out the battery fuse first. Perhaps the 100amp in the box too?
     
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  3. w2co

    w2co Member

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    Yes it would blow the 100A 12v fuse but it also could zap an ecu or two..
     
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  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Maybe even heavy rain could be a problem? Probably not, Christmas light extension cords never seem to mind, but who knows.
     
  5. w2co

    w2co Member

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    Installed Techstream on the xp laptop, a few years out of date but a fresh install w/all SP2 upgrades. It runs flakey on it, but I was able to log on to the vehicle and capture the HV ecu data list... Techstream_snapshot_8-22-19.jpg
     
  6. w2co

    w2co Member

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    And here is a few screenshots of AE connected to the same vehicle.... 06Prius_All_Systems_4-2-10.jpg 06Prius_HV ECU CAN_4-2-10.jpg 06Prius_HVecu_3-31-10.jpg 06Prius_MG1_MG2_Temps.jpg
     

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  7. w2co

    w2co Member

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    My key fob battery is low lately, so I just put it in the slot to drive it, see the dtc's from the body and smart key ecu's. It even picked up that my keyfob is low....
     

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  8. w2co

    w2co Member

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    As can be seen in the above snapshot, no battery temps have gone higher than around 94F so far, so I doubt the fan is even on. It also says fan mode 0. So until I get it hot enough don't think I'll ever actually hear the fan...Anyway here's a drawing from way back that shows the other circuitry involved with the battery fan. priusbatmgmt.jpg
     
  9. Luc_S

    Luc_S Junior Member

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    I'm currently doing maintenance of HV battery cooling system. Here are my observations and thoughts:
    - P2 battery blower uses a DC brushed motor. It's normal, that such motors doesn't spin freely as there is a good amount of friction between brushes and commutator. Recently I got two DC motors from salvaged plotters and they spin freely only with brushes removed.
    - My blower draws about [email protected],7V and [email protected] It starts moving at about 1.1V and keeps spinning at 1.2 V drawing about 0.7A (The current varies from 0.55 to 0.8A as rotational speed at such low voltage is not stable, so is a back EMF). The currents measured at 3.7 and 12V are very similar to these mentioned in this thread: Cleaned hv blower and battery. Battery temp now hotter | PriusChat
    - The service manual does not mention how much current the fan draws (amazingly it tells the current of cooler fans...). It only mentions that the resistance must be no more than 9 Ohms (mine is about 1 Ohm, which I assume is OK for the 12V/60W motor with healthy brushes).

    - in order to dissipate a certain amount of heat through a cooling system which has a specific thermal resistance we need a certain temperature difference. For example to dissipate 10W from a transistor through a radiator with thermal resistance of 1°C/W the temperature diference between transistor and ambient air will be 10°C regardless of actual ambient temperature - the transistor will be always 10°C hotter than air. If we use a fan to push air through a radiator - the thermal resistance will decrease and the transistor will be cooler despite the same ambient tempreature and dissipated power.
    Back to my prius - with fan operating at maximum speed the difference between inhaled air and battery is no more than 10°C(18F). At low speed it's at least twice as much. The problem is that charging current limit kicks in at 38°C(100.4F), but prius sets max fan speed loo late, so in hot days it's easy to overheat the battery and loose efficiency of regenerative braking. That's why I use HA to set level 6 of fan cooling at lowet possible temp (35°C/95F) and use AC to keep cabin below 28°C/82F.
    Today I cleaned the fan blades (about 20% of space between blades was clogged with very fine dust) - will see next days if it improved cooling efficiency.
     
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  10. dolj

    dolj Senior Member

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    Thanks, Luc, very informative post. Look forward to your update.
     
  11. w2co

    w2co Member

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    Thanks Luc, well our blower was clean already, just never heard it although no codes either. If that had a problem it would catch it in a dtc for sure. Well we just hit 1000 miles with no problems at all with the new prius batteries, and now it gets close to 60MPG! of course only after it's completely warmed up. It also charges up quicker too. When I did the battery swap, I moved all three temp sensors to the topside of the batteries. I finally heard the blower come on the other day...btw, these cylindrical battery modules allow much more air to flow in between them as well, Much better than the oem's much more constrictive airflow design. Anyway, it runs like new again..til next time!
     
    #91 w2co, Oct 3, 2019
    Last edited: Oct 3, 2019
  12. donbright

    donbright Active Member

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    I think there is a PID for the HV Battery Fan speed level, it will return a value of 0, 1, 2, 3.. etc. highest ive seen is 3, but i dont remember ever hearing it come on.. Here are some data i collected from Torque app, showing Fan Speed (green line at bottom) vs battery temperatures, (click to see full charts)
    newplot(3).png newplot(3).png newplot(4).png newplot(6).png
     
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  13. w2co

    w2co Member

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    Yup Don, the G2 prius is too little too late when it comes to the battery blower..I read somewhere it will never give higher than a 3 command even if the modules are melting! And of course that will come after it's too late...Winter is coming fast here so guess I won't have to worry too much now until next summer lol.
     
  14. dolj

    dolj Senior Member

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    Maybe you might want to locate the information "you read somewhere" and share it with the forum.

    That information just cannot be correct, as at level 3 you would not be really able to hear the fan, except if maybe you stuck your ear right up to the intake vent. We have had plenty of reports of the cooling fan running at level 6, such that it can be heard over road noise from the driver's seat while the car is travelling at speed.

    I have used the active test in Techstream and commanded the fan to all speeds and it responded accordingly, so unless there is a defect in the ECU programming, it is also highly unlikely that the fan cannot or does not, go above level 3.
     
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  15. w2co

    w2co Member

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    I read that way back a few years, probebly from here! Well I think it is one thing to command a "6" fan speed and totally another for the system to actually issue that. I believe it is in firmware and the fact that the temp sensors are installed in the bottom side of the modules. Some weren't even hard against the modules and had space between them. Heat rises! But I installed the sensors on top in the new pack. UPDATE: Just hit 2000 miles with the newpriusbatteries and running strong now, acceleration is a bit more stout than original and absolutely NO problems! No sign of battery blower yet, but it is winter now...
     
  16. dolj

    dolj Senior Member

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    I totally agree that they are two different things, but the tipping point is the fact that there many reported observations of the cooling fan roaring away in the back.

    Your report is the first time I have ever heard that the fan cannot be set by the control system at a speed greater than 3.
     
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