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2001 Prius -Where do I test the HV battery to get the 370v reading ????

Discussion in 'Generation 1 Prius Discussion' started by Bondobudie54, Mar 2, 2013.

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  1. Bondobudie54

    Bondobudie54 New Member

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    2001 Prius Hi I am having a problem testing the HV battery ...Where on the HV battery do I test to get the voltage ??? What setting do I use on volt meter do I use???? Thanks
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. The nominal voltage of the Classic traction battery is 273.6V.
    2. The highest actual voltage reading tends to be around 320V or thereabouts.
    3. Measuring total battery voltage is not a particularly good test of the traction battery.
    4. A better test is to measure module voltage of each of the 38 modules inside the battery to verify that each module has voltage very close to the others. Any module with significantly lower voltage needs to be replaced.
    5. In order to do any traction battery voltage testing, it is necessary to remove the battery cover which will expose you to high voltage and potential shock hazard.
  3. Bondobudie54

    Bondobudie54 New Member

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    Thanks for the reply Patrick

    I have worked around cars all my life , the Prius is just another chapter in my life!!!!!!!

    I know the HV battery voltage is between 320. to 273. at it's highest point.
    I have tested each individual with some surprising results with the lowest being 1.1 to 7.6

    I did use a HIMH to charger the individual , so I did not over charge any of them .

    My question still stands how do it test the HV battery as a whole.

    Also I would like to buy a good obd2 scanner to use with my PC so I can check the HV battery ......
  4. 3prongpaul

    3prongpaul 6 Gen1s, 3 Gen2s

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    You can test the entire Gen1 pack with a voltmeter (set meter for DC volts higher than 320, most use 500 or 600V scale) without removing the back seat, battery or even the battery cover.
    Remove the orange "plug to nowhere" on the drivers side of the battery. To get to it, pull aside the trunk liner on the drivers side from inside the trunk area so you can see it. Use the orange disconnect plug from rear of battery to spin the orange circle then remove the plug cover and carefully pull it out. There is 4-5 inches of cable slack inside. Remove the connector that has 3 wires. The two outer wires are full pack voltage when orange plug is back in at it's normal location. Be careful! You could hurt yourself with 320V and IIRC the color codes are opposite of what you'd expect with respect to polarity.

    From this plug you can measure voltage or even charge the whole pack if you have a suitable 320V DC charger.

    However, measuring voltage of the whole pack doesn't tell you much about health of the battery.

    It's more important to see how the block voltages and internal resistance compare to one another under load. The best test is having Techstream hooked up then drive uphill in reverse, since reverse uphill stresses the HV battery more than anything else.
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