2007 Hybrid Battery Not Discharging Like Normal

I have recently noticed a drop of about 10-15mpg since summer (I live in PA). I thought it was all due to temperature and fuel changes. I drive my car daily to work and school, and it currently has 156k. This morning I noticed that the hybrid battery level was green for my entire drive home, and the screen showed it discharging for only a split second when given power before it would switch to just the ICE. It would run off the battery consistently in low power situations (slowly coasting, heating the car in park), but once I gave it more gas the battery would not output power. However, both the motor and engine would be shown giving power to the wheels. This confused me because I thought that the only way for the electric motor to be driven to power the wheels was through the hybrid battery. Also concerning, the battery level was hardly ever a couple bars below full. While driving it around it was actually fully charged up a number of times which is very rare on my daily commute. Does this sound like a failing hybrid battery?

Edit: I drove home today and monitored the battery with Dr Prius. The highest I saw for voltage difference was 0.2x. The battery also showed that it was discharging normally, but it was still at a relatively high charge and would continue to charge even when it was close to full which it had not done before. What seemed super odd to me is that from the time I turned the car on to the time I turned it off, the ICE seemed to be constantly running. I can’t be too sure about this while I was driving because it’s hard to decipher the noise, but while parked the ICE was constantly running without being displayed on the screen, and with the battery at full charge and heat off. I just turned the car on again, parked and without any heat or lights and the ICE was not on for about 5 seconds. Then it kicked on and showed power going to charge the hybrid battery, which had only one bar less than full charge. I have only ever seen the ICE kick on to charge the battery while parked if it was only a couple bars full. Is this a more likely an ECU issue? Or possibly just normal operation? I know that one of the two hybrid ecu’s is malfunctioning because I was dealing with a battery fan code in the summer.

 

I am in fact low on fuel. Not terribly low, but around two bars going on one. It has been seeming like these last two bars are taking quite a long time to dissipate, so perhaps I am lower than I think and there is some sort of fuel gauge issue, which I have heard of but never had issues with myself. I’ll fill up tomorrow and see what difference I get. On another note, does my drop in mpg seem bad? It is close to 25% loss of efficiency. Granted, I have been doing more rural driving than highway which was not the case in the summer. This could be part of the cause.

 

This sounds a little complicated but I’ll definitely give it a shot once I have time. When you say turn the car off and you can go home, do you mean turn it off and back on before heading home, or turn it off once I get home? And is this stuff all done as one test, or are they separate from each other?

 

Just checked. I have a p3000 code. I’m thinking about taking it to Toyota to get the subcode. Still getting over 40 mpgs so is a failing battery even likely?

Edit: I actually remembered this code is from the malfunctioning ECU which will sparatically cut of power to the fan, but still operates fine. It only comes on when weather is around at least 50 degrees and I am driving for a while. Don’t think it has anything to do with the battery itself.