HV Battery charge question for battery gurus

Discussion in 'Generation 1 Prius Discussion' started by Nelsonprius, Nov 14, 2019.

  1. Nelsonprius

    Nelsonprius Junior Member

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    2001 Prius
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    I
    Bought a Gen 1 , works well except it rarely drives in electric only, I thought it might run electric for 1/4 mile to 2 miles. Am I wrong on normal operation?
    Bought a Carista OBD2 and used Dr Prius app to look at battery.
    Dr Prius shows battery normally around 67% STATE OF CHARGE.
    Driving up long hill it went down to 62% and coasting down long hill 2miles it reached 75% with all the individual cell bars showing yellow bars.
    Pack Voltage going up hill went down to 290V and coasting down hill reached 350V , batteries were 50*F and voltage diff was 0.12 to 0.20.
    While idling after the hill test, the battery shows a discharge rate of 2A, not charging.
    Can anyone interpret the battery condition for me?
     
  2. Josey

    Josey New Member

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    There are likely others who can comment better on the technicals than I. But at the very least, I can say that the 1st Gen Prius doesn't do electric only except for very low speed with very light throttle, or when gravity is on it's side (e.g. downhill) - so it's really about how much throttle/power you're asking for from the car. It takes very little for it to need the gas engine. Think of the Gen 1s as gas powered vehicles with electric assist. In other words, electric is secondary rather than primary.

    A DSOC above 60% is good. So 60-75% indicates no problem. The only note that I found odd was the yellow bars on a downhill. They should be green, but this is where I come up short on being sharp on the technicals. Yellow is "caution" (while red is bad). On a downhill with something like 75% DSOC, it seems to me that nothing should be yellow. But I also know that I've seen red on my pack voltage temporarily while doing downhill - meaning the pack was getting into overcharged. (It was well over 300V). But this was also highly brief and temporary. And the colors are also based on whatever the app developer decided in terms of in-bounds and out-of-bounds, and I'm not saavy enough to lay out where things should be and when. But you might have seen yellow because things were bordering on overcharge. But I'm sure that just happens - the module voltages and overall voltage are constantly up and down (more down on an uphill and more up on a downhill).

    I guess the other odd thing would just be that you refer to idling after the "hill test" - after the uphill or the downhill? With a healthy battery, and the car all warmed up the gas engine should shut down pretty quickly after you come to a stop. If you were just on a downhill it might be off already when you come to a stop. So does "idling after the hill test" mean just sitting in Ready mode? Or do you mean the gas engine was actually idling? Whether the gas engine runs can depend on more than just what locomotion or the battery needs. E.g. nothing makes heat in this car except the gas engine. So was it cold out and you had the heat blasting? Or was it hot out and A/C was blasting. In any case, not enough info to evaluate your last comment.

    But mostly, it sounds like the battery is doing just fine.
     
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  3. Nelsonprius

    Nelsonprius Junior Member

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    I
    it was engine idling after the long downhill, with the battery discharging at 2A. I didn't understand why it would discharge without the electric motor running at idle, but since it was yellow bars at the end of the downhill charge-up , I guess it was over charged at 75% and it was self regulating the over-charge with a discharge? It was cold so heater was on.
     
  4. ronlewis

    ronlewis Member

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    I'm not a guru either, but your numbers approximate what I see with my cars. Just to clarify, after warming up and then coming to a stop, the gas engine will normally shut down UNLESS you're running that A/C, heater, ?, that require gas engine to work. I imagine you were seeing a 2a discharge at idle exactly because you were running the heater. Once the HV battery discharged enough from that usage, the gas engine would automatically turn on to charge the battery back up, then turn itself off again.
     
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