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Charging a older HV battery that has been sitting..

Discussion in 'Gen 2 Prius Main Forum' started by Chris Blanchard, Jul 22, 2024 at 10:36 PM.

  1. Chris Blanchard

    Chris Blanchard New Member

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    Hi all I have a gen2 Prius, I have had the HV battery pack I replaced my original one with start throwing red triangle and codes. So My question for everyone, I have the one that worked fine in it sitting for like 2 years, can I just throw it in and have the car charge it up like normal or do I have to charge up each cell in the pack? It was not throwing codes or triangles, I had planned on cleaning up the normal corrosion (which I will now before putting back in) on the terminals and such, but decided to use the one I rebuilt in it instead. Thanks!
     
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    It's VERY unlikely your old battery pack is in any type of condition to function, and is most likely about completely discharged after sitting 2 years. At a minimum, there will be several modules that are completely discharged, making the battery useless for installation. Remember, the HV battery is the power source for starting the engine. If the ecu detects any failures of the HV battery, it won't even allow the main relays to close, so the HV battery never even gets put into the circuit. If you don't have a way to charge the pack all at once, it's possible you can do 1/2/3 at a time with a hobby charger. Charging them is in no way guaranteeing the modules are still functioning properly.
     
  3. Tombukt2

    Tombukt2 Senior Member

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    I would just be curious to know what your voltmeter tells you on DC volts sitting right there right now 196. ? That should only take a second to read. Then after that you look at the bus bars and nuts and look for the copper getting the patina on it looks nice but not good for electricity conduction frosted nuts All of those things If I saw 125 plus volts I might put my hobby lamp on it and let it discharge somewhat and then put my charger back on it and charge it back up with my charger when there's no change in voltage for 5 minutes charging up then you disconnect the charger but it stands a while to recheck the voltage and then do another discharge and then another charge and so on and see what happens obviously you have time so that's not the issue.
     
  4. dolj

    dolj Senior Member

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    It's more like 4 to 6 hours, not 5 minutes.
     
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  5. Tombukt2

    Tombukt2 Senior Member

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    No what I'm saying is is when I hook up my Venice hybrid pack charger to a hybrid pack depending upon where the battery is when I connect the charger I run the charger until there's no change on the chargers voltmeter which is reading the battery in 5 minutes so if I look at the charger and it says $230 volts in 5 minutes if it doesn't go to 231 I disconnect the HV charger as the battery is accepted the voltage it's going to accept That's the recommendation from the manufacturer of the charger. No the battery will not charge in 5 minutes typical though if the battery is sitting at 150 volts 157 volts or something like that usually in about 2 hours I'll be sitting at 2:11 2:30 somewhere in there I have not tried to charge a pack that's sitting at zero DC volts that I know of
     
  6. Tombukt2

    Tombukt2 Senior Member

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    This is charging it 300 volts at 2.4 amps
     
  7. dolj

    dolj Senior Member

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    Yes, I understood that's what you meant. There is no way you can charge past ~ 220 V by waiting only five minutes. If you look at the graph below which shows a typical charge session it takes progressively longer to raise the battery voltage by 1 volt.

    The recommendation from the Hybrid Automotive is that when you do not see the voltage rise within 4 to 6 hours then you stop the charge. If you do not do this, you will not top balance the battery.

    On the graph (below), the two rightmost solid vertical lines denote 6 hours. The dotted vertical line (between them) is 4 hours.

    The next pair of solid vertical lines to the left is ~ 40 minutes and marks the time the voltage took to rise from 235 volts to 236 volts.

    If you can raise the voltage by 1 volt (above 235 volts) in less than 5 minutes, your battery is pretty cr4p. The healthier the battery the longer it takes and also the lower the top ceiling voltage.

    upload_2024-7-24_1-56-25.png

    Detail matters.
     
    #7 dolj, Jul 23, 2024 at 10:09 AM
    Last edited: Jul 23, 2024 at 10:16 AM
  8. Chris Blanchard

    Chris Blanchard New Member

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    I just measured the voltage and the pack says its about 211V DC. I am surprised its still that charged up. Im going to clean up the terminals and throw it back in the car, it should start the engine with that much in it. Just curious what do you guys use to charge up the pack / cells? I have seen a few recommendations for hobby racing car chargers.
     
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  9. Tombukt2

    Tombukt2 Senior Member

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    Like I said this is very common so clean up the mess see if you got any leaks anything swollen look under the modules on the tray with a flashlight and go from there That's what I expected you to find pretty much a good show.
     
  10. Tombukt2

    Tombukt2 Senior Member

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    This is just what the manufacturer of the Venice hybrid charging system Raj is his name said to me when I got the system from him when it's connected and it's working when it reaches voltage and doesn't change in 5 minutes you should disconnect the charger You can leave it on a while if you want see if the battery pack starts to heat up and then disconnect it once you start generating heat you're pretty much done with charging so I think his advice seems pretty reasonable that was not going to happen that 5-minute change until the battery is pretty much charged up to 80 85 87% somewhere in there That's probably what it works out to be You're not trying to blast it up to 100%