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System reset for new pack?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pasadena_commut, Nov 28, 2023.

  1. pasadena_commut

    pasadena_commut Senior Member

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    A new OEM pack was installed recently. Is there anything that needs to be "reset" using Techstream to tell the car that it is a new battery? (Apparently some cars have things like that for 12V swaps.)

    Our 2007 has a new pack as of a couple of weeks ago, and it didn't get driven much since. However, today I drove it from SoCal to the Bay Area. No problems, but the MPG was a little lower than the exact same trip (same speeds, same conditions) as last year. Based on the car's estimate, it is about 1 MPG less. Could be noise. Could be the lack of a reset if one was needed. Or it could be dozens of other things (a slightly dirty spark plug, slightly clogged injector, and so forth.) The car drove perfectly normally, and no battery issues whatsoever. The only thing that seemed odd was that on a flat road using cruise control no wind and no other vehicles nearby the "current mpg" would dance around rather a lot. Like up to 60 and down to 35. Never noticed that before. Could be that there was a slight undulation to the road though which I couldn't see but the car could detect.
     
  2. pasadena_commut

    pasadena_commut Senior Member

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    Also, you know how there is always some Porsche or Corvette or something like that that goes barreling by at >90 mph? Today the only car that did that was a 3rd Generation Prius. The driver must have had his foot all the way to the floor.
     
  3. JC91006

    JC91006 Senior Member

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    There's no reset. 1mpg could come down to different air pressure in your tires
     
  4. pasadena_commut

    pasadena_commut Senior Member

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    Not likely though, as both times they were inflated to the same values and checked with the same tire gauge. Not that I was trying to eliminate a variable, but because I always check tire inflation before trips.

    When I get home my son can ride shotgun and check the live measurements with Techstream while I drive to see if there is some hint there. Probably won't see anything out of whack. Still, worth a look.
     
  5. JC91006

    JC91006 Senior Member

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    there are really a bunch of variables but the battery pack should not be one of them. If anything the new battery pack will only help with your MPG.

    You have so many things that wear on a car with higher mileage. Tires, 12v battery, brakes, suspension, injectors, fuel pump...I mean the list is endless that can decrease your mpg
     
  6. Tombukt2

    Tombukt2 Senior Member

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    I will add that when I got my new Toyota battery from Toyota parts in Central North Carolina and installed it It took about $120 days until I started seeing real good mileage and green on the display is the things that I watch just because there's nothing else to do when you're driving the Prius and I know in my vehicle's exactly when they will change from blue to green and all of that even in parts of the road where I'm at I can tell what the battery is going to display when I'm going down that section of road because I do it that often My route is the same etc but when I initially put the new battery in it took about 6 weeks maybe even eight until I was back up in the 48 mi to the gallon range when I initially put the battery in it was in the 43 44. And I never saw green until 120 days out I would see full blue never saw the magenta or red but I never saw it flop from full blue to green until 120 days in now maybe if when I first got the battery if I would have put it on charge with my Venice hybrid charger until it was full completely maybe things would have been different I don't know it was the first time I replaced the hybrid battery and a hybrid car so I just put it in there now looking back maybe I should have charged it like I would a 12 volt and at the time I didn't have the Venice hybrid charger that would do the whole pack at once so that was another thing.
     
  7. pasadena_commut

    pasadena_commut Senior Member

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    Our new battery charged up to green in the first day or two (don't recall which). It hasn't been below blue since then, that I have noticed, including driving up I5 out of LA towards the central valley yesterday, which is a very long uphill grade. If anything it is a little too aggressive with the pack charging, since it was green and only one bar down at Lebeq at the top of the grapevine. Would have been better had it been mostly discharged there since the elevation change going down the grapevine is 2613 feet and the car had to dissipate most of that energy rather than store it.

    I would assume the ECUs do some sort of optimization based on the state of the pack, but don't know if unplugging the 12V is enough to reset that. If it isn't then there would be some sort of long term learning curve so that it can average out all the different driving conditions.
     
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    I have always found the battery "gauge" and MPGs to be abnormal for awhile after disconnecting 12V power. Same was true after installing a new Toyota pack I assume that the ecu's have to learn some adaptions. Seemed to settle out after a few hundred miles.

    Posted via the PriusChat mobile app.
     
  9. PriusCamper

    PriusCamper Senior Member

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    Usually a loss of MPG can quickly be addressed by boosting tire pressure. But when you're talking about 1mpg less on a car that gets near 50mpg that's way more minor and ever changing than 1mpg less on a 10mpg vehicle.
     
    dolj likes this.