Hi All, I bought a 2005 Prius about 8 months ago and rebuilt the battery pack with help from this site. The battery was bad when I bought it so I have never been absolutely sure the battery is behaving the way it ought to. When I am driving down the highway around 65 mph, the battery seems to continually cycle charging and discharging in maybe 3 second intervals. The battery never seems to get below 80% unless the car is driven slow through city streets or left running when parked. Is this normal?
no. the battery isn't used all that much on the highway at speed, unless you're in mountainous terrain. how are your mpg's?
Yes it’s normal, if you only mean the arrows cycling. Battery should stay at 6 bars on steady driving on flat highway. If you let it sit long enough battery will drop to 2 bars and then engine will charge it up a bit. Unless something like heater commands engine to start before that.
The arrows will switch frequently, but if one adds actual metering of the current level via the OBDII port, it shows that the actual amount of current being switched in that case can be quite small. The HV ECU will micromanage the situation, but there is not that much happening despite what the arrows say.
Those arrows would actually be useful if they somehow gave a hint as to the magnitude of power flowing into or out of the battery. As they are, they just confuse people, because insignificant currents look exactly the same as high currents. They reveal the sign, but not the magnitude of energy transfer.
