Prime battery experiment

Discussion in 'Prius Prime' started by bwilson4web, Aug 5, 2018.

  1. bwilson4web

    bwilson4web Active Member

    When the 90F (32C) weather arrived in June, the 2017 Prime had three, full charge sessions in the heat of the day where the kWh decreased from ~6.1 to 5.9 kWh. With an air cooled battery pack, this alarmed me because the air cooled, early Leaf had problems of high temperature degradation. So I parked the Prime in the shade with 4% SOC and switched to the liquid cooled, BMW i3-REx.

    I learned with the earlier Prius, 2003 and 2010, that not driving 4-6 weeks can lead to a dead 12V battery. I also worry about lubricants thinning on the moving parts. So I swapped the Prime with the BMW two days ago and drove around after midnight, ~73F (22C) long enough to get the engine warmed up and lubricated. But I held off charging until ~4 AM to maximize cooling and got a 6.1 kWh charge.

    The Prime has an exceptionally efficient hybrid mode, +60 MPG around town. By going home as soon as the traction battery is discharged, I can use time-of-day scheduling to charge the battery between 4 - 9 AM. This maximizes battery cooling during the hot weather. I'll burn a little gas but I had bought in January. So I'll also burn up the 'stale' gas.

    I want to run the experiment of at least a week. This will determine if the traction battery kWh is stable. It also means time-of-day charging tweaked for temperature is a practical way to keep the battery in good condition.

    Bob Wilson

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