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Hybrid battery problem

Discussion in 'Generation 1 Prius Discussion' started by 1towman, Apr 7, 2024.

  1. 1towman

    1towman Junior Member

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    So I have a 1st gen that sat for a long time with a bad hybrid battery. I bought a used battery out of a wreck and would like to find out what I need to do next. From what I found out from the previous owner, the supposed good battery sat for about 2 months. Could sure use some advice.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Yeah the first gen has a funny interesting battery anyway maybe check the voltage across the terminals there should be some diagrams here on this Prius site on how to do that It's DC volts. And see what kind of voltage you have just sitting there I've seen these batteries after six seven months still have 205 volts 212 whatever at least in my generation too so I wouldn't be surprised if the battery sitting there with enough voltage to actually kick over the motor when it's bolted into the car It can be charged with a DC charger but it's going to need to be a pretty stout charger made for hybrid battery duty and they're not cheap so ideally check the battery see what kind of volts you have and then go from there while you're looking at the battery you might want to lift the cover up and take a look at the copper bus bars and the nuts that join all the modules together this is where things get interesting and the corrosion can cause problems voltage drops and all of that so you want to make sure that stuff is clean with the safety plug out you can safely clean and undo bus bars and things like that It may be something that needs to be looked into.
     
  3. dabard051

    dabard051 Tinkerer-in-Charge

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    Hybrid battery on a gen 1 uses a set of 38 7.2 volt NiCd batteries to obtain the 273 volts needed for the system.
    Does the car start?
    Note, if it sat for a while the 12v battery may be flat (that's the power source for the onboard computers), then the first item of business is to put a good charge on the 12v battery.

    Try this first with the in-place "bad" HV battery, and confirm that it's really bad.

    Then do the HV battery swap, and try it again. I found that using some 2x4x4' boards and "walking" the HV battery out through the trunk up a pair of 2x4s is the easiest way for a single individual to get the HV battery out. It weighs on the order of 100 pounds. A battery operated drill doubling as an electric screwdriver, with a square adapter for 10, 12 & 13 mm sockets plus a 6" (150mm) extension is REALLY helpful (there are lots of bolts to undo), plus a 10mm deep socket for the HV cables from battery to inverter.

    If the car starts, (even with warning lights on the console), try driving it around, clear the fault codes, drive some more, and see if the vehicle charging system can exercise the HV battery enough to make it reasonably healthy. The usual problem is that the pack has too large a voltage difference between high and low of the cells (i.e., some cells are weak), and that sets the fault code. The usual culprits are the two cells closest to the computer end of the battery pack.

    If the car does not start with a healthy 12v battery, then that requires recharging the HV battery or replacing it, both of which are discussed in any number of other threads.

    In any case, a friend with a TechStream can help you get information on the state of the HV battery.

    Tombuktu, is punctuation expensive on your keyboard? That's one of the longest run-on sentences I've ever seen in a post..... :)
     
    #3 dabard051, Apr 10, 2024
    Last edited: Apr 10, 2024
    jeff652 likes this.
  4. dolj

    dolj Senior Member

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    Are you sure about that? I always thought the Gen 1 used NiMH modules like the Gen 2.
     
  5. Tombukt2

    Tombukt2 Senior Member

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    Looks like NimH to me. There's one sitting out here in the yard The replacement for a 2003 generation 1 completely different shaped and everything then the generation two battery but I'm almost positive it's nickel metal hydride. Believe it says so right on the sticker I'll check this morning.
     
  6. dabard051

    dabard051 Tinkerer-in-Charge

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    I seem to recall that Gen I and Gen 2 battery cells are different size, and the chemistry moved from NiCd to NiMH.

    But I'm an old guy; memory might not be correct.
     
  7. dolj

    dolj Senior Member

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    You might be thinking of the first Prius released only in Japan, which has come to be known as the Gen 0 (zero).

    I don't know for sure about the Gen 0, but pretty sure the Gen 1 has always been NiMH.
     
  8. ronlewis

    ronlewis Active Member

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    I'm not sure what rabbit hole these guys are leading you down, 1Towman. They seem to have commandeered your thread. From what you posted, you just need to swap the battery you bought into your car from the wreck. It's an easy job - about 2 hours, but first time probably twice that. You learn how it works removing the battery from the wreck. Then removing yours is easier, and by the time you're putting yours in - no problem.

    What you want to do first is disconnect the 12v batteries and pull the orange plugs on the HV batteries on both cars and let them sit for 20mins while the system capacitors bleed off. You will be working on taking the seats and battery ductwork out.

    The other way to kill yourself is to accidentally stick your finger into the hole where that orange plug came out. It's easy to do when you go to lift the battery in/out of the car. You can put some duct tape over it to remind you.

    Otherwise, I'm sure there's plenty of YouTubes and threads here on the process. I can copy PDFs from the service manual if you need.

    Once it's all back together, you don't want to drain the HV by trying to start the car if the gas engine is failing. If the gas engine bogs and misfires before dying and thrown codes/triangle, you really need to solve that. Typically plugs/coils/injectors/throttle body/MAP got dirty sitting up. Might have to remove/clean/replace.