Power Consumption

Discussion in 'Gen 2 Prius Audio and Electronics' started by kk6yb, Jan 10, 2006.

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  1. kk6yb

    kk6yb Junior Member

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    One of the things I wanted to examine in the Prius was the power consumption of various components in the car and their relation to fuel economy. So after installing CAN-View I decided to collect a little data.

    I measured the wattage my examing the ampere consumption on the HV battery and multiplying by the HV battery voltage to get the wattage. This was done while the car was in park, with the ICE off and all accessories turned off. Then I would turn on one accessory at a time to see what the new power consumption was. This gives the power consumption including the DC-DC converter's conversion cost due to < 100% efficient power conversion. In cases where the readout kept flipping between two numbers (ie: alternating 1.1 and 1.2) and used the value in between (ie: 1.15).

    Here's what I found with my '05 Prius. All of the amounts (except the minimum consumption) already have the minimum consumption subtracted.

    Minimum consumption: 1.15a 232v (267 watts)
    Parking lights only: 0.15a 230v (35 watts)
    Parking + HID on: 0.75a 231v (173 watts)
    Parking + HID + fog: 1.35a 230v (311 watts)
    Rear window defogger: 1.6a 230v (368 watts)
    Fan on M (AC off): 0.45a 230v (104 watts)
    Fan on H (AC off): 1.25a 230v (288 watts)


    For reference it takes about 6,000 watts to drive the car at 40 mph. So adding 600 watts of accessories would cut FE by about 10% at 40 mph.
     
    #1 kk6yb, Jan 10, 2006
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Interesting. Thanks!
     
    #2 Tideland Prius, Jan 10, 2006
  3. tmorrowus

    tmorrowus Member

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    Thanks. Appreciate your getting that info. So it sounds like a typical load for HID lights, minimum consumption, and fan on low would be in the ballpark of 400-500W.
     
    #3 tmorrowus, Jan 10, 2006
  4. DanMan32

    DanMan32 Senior Member

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    Shouldn't it be 207V?

    Considering that the HID bulbs are 35W apiece (70W total), I'd wonder where the extra wattage is going.
     
    #4 DanMan32, Jan 11, 2006
  5. kk6yb

    kk6yb Junior Member

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    No, 207v is too low, that's < 45% SOC. The reported SOC was 66% and 232v is what appeared on CAN-View when I took the measurements. Not far off from Wayne's voltage/SOC chart.

    Based on the article you linked to (very interesting article), the bulbs take 35 watts of high voltage *into the bulb*, so depending on the conversion efficiency of the ballast, it will take more than 35 watts off the 12v bus. Then there is the conversion from the HV battery voltage to the 12v. Still it surprises me that the conversions are that inefficient.
     
    #5 kk6yb, Jan 11, 2006
  6. hdrygas

    hdrygas New Member

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    What no stereo figures! That looks about right from what I see on the CAN View. The thing I find interesting is the amps more than double in glide mode i.e. no power arrows on MFD over at rest at a stoplight. Where is the power going? Why? When I get upgraded to the beta software maybe there will be answers.
     
    #6 hdrygas, Jan 11, 2006
  7. efusco

    efusco Moderator Emeritus
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    Front defrost, max heat, max cool (both with A/C on) would also be good additions.
     
    #7 efusco, Jan 11, 2006
  8. Tempus

    Tempus Senior Member

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    I thought about that when looking at the new Hybrid Camry specs.

    The stock stereo is about 160 Watts. The upgrade is over 400 Watts.
     
    #8 Tempus, Jan 11, 2006
  9. kk6yb

    kk6yb Junior Member

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    I tried these this afternoon when leaving work but it's not so easy with these. The SOC was lower this time 57% and the ICE was cold.

    Front defrost immediately turns on the ICE, which swings the amps reading all over the place since it starts charging, etc.

    EPS - Electronic Power Steering takes about 0.9a 220v (198 watts) when you swing the wheel back and forth.

    JBL CD Player - with volume up loud - no visible difference in amps consumption.

    A/C - Outside temp 55F, set inside to 66F, Auto, A/C on - uses 0.25a 220v (55 watts). I bumped the temp setting up 1 by 1 to try to get the heat to come on more but there was no change in consumption. When I hit 70F the ICE came on.

    I'll have to wait for a warm afternoon to try the A/C cooling. I know I can get that to work without turning on the ICE (except at Max Cooling).
     
    #9 kk6yb, Jan 12, 2006
  10. ken1784

    ken1784 SuperMID designer

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    Where does the 207V number come from?

    Ken@Japan
     
    #10 ken1784, Jan 12, 2006
  11. hdrygas

    hdrygas New Member

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    I was fooling with the JPL and the Volume control. The amps would go up briefly then go back down to base level. I never got the Volume to the pain level.
     
    #11 hdrygas, Jan 12, 2006
  12. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    defrost is a tough cookie to figure because it almost always kicks the ICE on right away. what i tried to do was to drive with CC on, flat ground, ICE running and flipping defrost on and off the check instaneous changes and curent draw seems to be about 3-5 amps.

    very tough to measure though.

    ive been working on different accessories for a while. interesting thing is that im also tracking mileage on short trips and half are at night, the other half during the day, headlights are not making any difference that i can see. but i dont have hid, fog or none of those energy hogs...that might be why
     
    #12 DaveinOlyWA, Jan 12, 2006
  13. hdrygas

    hdrygas New Member

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    Wipers. Wipers are really important around here. For the front and back I am getting .2-.4 at the most but it does vary from nothing (no change) to .2. It does not appear to go over 1. I also have to say at this level it is very difficult to make any call the way the Amps jump around.
     
    #13 hdrygas, Jan 13, 2006
  14. DanMan32

    DanMan32 Senior Member

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    From New Car Features:
    The HV battery of the ’03 Prius consists of 228 cells ({1.2V x 6 cells} x 38 modules) with a nominal voltage of DC 273.6 V. In contrast, the HV battery of the ’04 Prius consists of 168 cells ({1.2V x 6 cells} x 28 modules) with a nominal voltage of DC 201.6 V. A compact and lightweight battery configuration has been achieved through these internal improvements.
    • On the ’03 Prius, the connection between the cells of the HV battery consists of one spot. In contrast, the cells on the ’04 Prius are connected with two spots. The internal resistance of the battery has been reduced by this improvement.

    From owner's manual: (Specifications section)

    Hybrid vehicle battery
    Type: Nickel–Metal hydride battery
    Voltage: 7.2 V
    Capacity: 6.5 Ah (3HR)
    Quantity: 28
    Overall voltage: 201.6 V

    Canview is only as good as its calibration. That diagram may have been for a classic, as he seems to switch back and forth on his descriptions. I suppose the only way to know for sure is to take a voltmeter to the battery.

    JBL amp has main power fused at 30A, radio shares 15A dome fuse with a host of other stuff. 400W (33A@12V) would sound a tad excessive at no volume, and an awful waste for standby power. At full volume that might make sense, considering power conversion inefficiencies.
    Come to think of it, 400W with normal sound level makes no sense, as one can operate the radio quite successfully in ACC for over an hour. At 38AH battery, it would be dead in 1 hr 9 minutes. Although ACC turns itself off after an hour, I did run the radio twice for 1 hour sessions while helping my dad with the Christmas lights.
     
    #14 DanMan32, Jan 17, 2006
  15. ken1784

    ken1784 SuperMID designer

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    I see 201.6V.
    I'm asking where is the 207V.

    Ken@Japan
     
    #15 ken1784, Jan 17, 2006
  16. DanMan32

    DanMan32 Senior Member

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    201, 207, its around there. Misremembered the exact number I guess. 230 is certainly way off.
     
    #16 DanMan32, Jan 17, 2006
  17. ken1784

    ken1784 SuperMID designer

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    Reading the CAN messages, the 230V is very common value.

    Ken@Japan
    [Broken External Image]:http://bbs1.fc2.com/bbs/img/_10800/10794/full/10794_1128350133.jpg
     
    #17 ken1784, Jan 17, 2006
  18. Frank Hudon

    Frank Hudon Senior Member

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    Classic voltage is normally around 293-297 and as high as 335 volts at full change, 80% just before you can't get any more in it on a long downhill.
     
    #18 Frank Hudon, Jan 17, 2006
  19. Frank Hudon

    Frank Hudon Senior Member

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    these only report what is on the network, not what is taken from the battery. Altough both are almost the same if not the same. There will be some small drop over the cables to the battery but the Battery ECU sends the data to the Network to be processed by the HV ECU. Graham Davies say's that the normal Classic HV battery voltage is normally about 300 volts.
     
    #19 Frank Hudon, Jan 17, 2006
  20. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    230 volts is average for me. mine rarely as low as 200 but frequently as high as 275. did have it at 173 once... but that was at 60 mph on a pretty steep climb.
     
    #20 DaveinOlyWA, Jan 17, 2006
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