What is "normal" HV battery SOC?

Discussion in 'Gen 2 Prius Technical Discussion' started by mr_guy_mann, Jan 24, 2021.

  1. mr_guy_mann

    mr_guy_mann Member

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    So, as I use my 2006 as a daily commuter for the past 4 months and 5000 miles after refurbishing the HV battery to about 5.5Ah, I have noticed that the "battery gauge" stays at 6-7 bars . Dr Prius or a scantool show SOC staying somewhere between 60-70%. I drive about 80 miles per day, 1/2 on interstates at 80mph and 1/2 on local highways at 40-60 with moderate hills. I don't pulse, glide, or hyper-anything. I flog this low powered beast to keep up with traffic and have little concern for the actual mpg.
    My question is, what is a "normal" range for SOC on a healthy battery under different conditions? Should I occasionally force the battery down some then let it charge up again? I imagine a car in slow traffic with AC on is different vs local cruise on the flat vs highway with hills. Just trying to learn what "good" is so that I can find the bad when I see it.
    I have read that the ecu tries to keep SOC between 40-80%, but that's a pretty broad range and doesn't match what I see on my car.
     
  2. dolj

    dolj Senior Member

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    That is pretty normal for a well balanced battery.
    You maybe have misunderstood. The battery ECU will only use the available range of 40% SoC (lower limit) to 80% SoC (upper limit). But it tries to keep the battery at around 60% SoC to allow room to store energy from regeneration but still have enough reserve for demand from the battery.

    So, from what you have said, your battery is acting pretty normally.
     
  3. jerrymildred

    jerrymildred Senior Member

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    That looks perfect!

    Nooooo!!! Unless you want to wear out the battery faster and get worse mileage to boot. The computer knows what to do. Let it do its job.

    Actually, the car insists on keeping it in that range. That's how they can offer such a long warranty on the battery. It will not let it go above or below that. (Except that I've read of people running out of gas in Gen 2s and continuing to drive on battery till the battery is totally dead.)

    Quite different. The car uses 6 bars as sort of a home base. If you're stopped in a traffic jam and the A/C runs it down to about 2 bars, the ICE will start and charge it back up. Having bars 7 & 8 available gives room for storage of energy regenerated braking or descending hills. I like to think of it a little like a spring that can compress or stretch. If it was kept fully compressed, it couldn't absorb energy in one direction. If it was stretched out, it couldn't absorb it in the other direction.

    Here's a very helpful document from @john1701a. John's Stuff - Toyota Prius User-Guide (Iconic)
     
  4. RRxing

    RRxing Senior Member

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    Correct. The indicated range on the display only shows the actual charge from 40-80%.
     
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