Hybrid battery cooling fan running constantly, lots of warning lights!

Yep

Mostly age, partly because of hilly use, and because I have this unproven impression that the car battery 'fills up' (reaches all green bars) quite a bit quicker than when the battery was new.

I now have the ability with the Android app 'Torque' to grab some measurements, so I'll be on firmer ground with my guesses once I have some data.

 

Ok thanks for the info.

I was curious because my 2005 also displays similar symptoms. Filling up more readily to the green bars as you describe, but also kind of "overshoot - undershoot" type of behavior on the state of charge after the battery has had any large SOC fluctuation.

At the moment I'm "nursing" mine a bit, by trying to let it (ICE) warm for a minute in the mornings, and by using "B" mode of larger downhills (when I can remember to do it).

Once you do get the torque app sorted out I'd be keen to know if you do discover anything interesting going on with the battery. Please post a thread if you get interesting data, my battery might be quite similar.

 

This is not my experience. On level terrain, at constant speed my MFD is constantly showing the ICE and electric swapping over taking turns at powering the car and charging the battery.

 

The arrows can be twitchy sometimes, but if you were to look at the actual current values involved, using the very worthwhile Prius software monitors, like Priidash, you would find that the magnitudes are small. The arrows give no indication of amount, just direction. Since the battery can not propel the car at highway speeds for long, the ECU's will not make much use of it and the possibility of overheating is reduced when a weak battery is in use.

 

In addition I can see the instantaneous consumption going up and down in conjunction with the ICE/Motor dance, so it must be doing something worthwhile, regardless of the magnitude of the current (which I don't doubt, incidentally). I'm not trying to imply the electric motor propels the car on its own, just it does do some worthwhile assistance, BTW.