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HV Battery Swap

Discussion in 'Gen 2 Prius Main Forum' started by Gunnar Boag, Mar 27, 2023.

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  1. Gunnar Boag

    Gunnar Boag Junior Member

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    2008 Prius
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    Well, it finally happened. My HV battery quit on me. I bought my Gen 2 used at 131,000 and it ran so well I didn't even think about the possibility of the battery failing. A few days ago the battery starting fluctuating like crazy. I` figured something was starting to go wrong, so I researched replacement options. And what do ya know, the next day I get the red triangle of death. I got a bluetooth OBD reader (super handy by the way) and verified that the battery needed changing.

    I looked into every option. Greenbean, Greentec, replacing cells, finding one on Ebay, and the dealer route. I ultimately went with the dealer, only because I wanted the security of having a new battery in there. Sure, you are at the mercy of their prices, but a new battery is great peace of mind for me.

    So here is my question: will I see a big change in mpg with the new battery? Does the mpg in a slowly dying HV battery drop over time, or is it a sharp drop in a month? It felt like I had lost good mileage over the past few months, but I chalked it up to winter time conditions. I'm hoping to get back to mid 40's, but I want to hear people's experiences after putting in a new HV battery.
     
    #1 Gunnar Boag, Mar 27, 2023
    dolj and bisco like this.
  2. bisco

    bisco cookie crumbler

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    congrats, goodmove!

    i suspect your mpg's will be much better. but unfortunately, there are many other things that might be affecting them.
    watch and wait is all you can do for now. if they don't improve, you'll have some research and work ahead of you.
    all the best!
     
    #2 bisco, Mar 28, 2023
  3. pasadena_commut

    pasadena_commut Senior Member

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    I would imagine the change in MPG would depend a lot on how you drive. For in city stop and go driving you should see a large change, for constant speed highway usage very little change. It shouldn't go down though! Well, maybe initially a little, as they would have detached the 12V battery to do the work, so the ECU will need to relearn.
     
    #3 pasadena_commut, Mar 28, 2023
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