2005 prius 242000 miles. new oem battery 8 years and 85k miles ago. first 800 miles battery would be at 5 or 6 bars pretty much all the time. recently i had the cooling fan cleaned out, at which point i also discovered the duct wasn't totally sealed between the fan and the battery. after cleaning the fan and sealing the duct the battery almost "woke up" in so far as i could be in ev mode a lot longer, in "grocery store parking lot" situation as well as 30-40mph on a slight decline, that kind of thing. i figured the cars computer was preventing the battery from working too hard because without the proper cooling it would overheat otherwise. a couple hundred miles after the fan cleaning, aka the last few days, ive noticed that for the first time the battery will go up to 7 bars and turn green, sometimes the full 8 bars, when im going downhill (no brake and no throttle, just the normal coasting w/ automatic regen braking). is that normal? just different than what ive experienced before so i thought id run it by you guys! edit: another variable is that the previous owner was switching to "pedestrianism" where he uses mass transit exclusively (reason for selling the car) and as such in recent times he wasn't driving it as much. i however am daily driving it so the car is seeing a lot more use, which i understand the battery should be happy about. could the increased usage also be a faactor for the battery being able to be "fully charged' with the full 8 green bars?
yes, completely normal, not sure why you were not seeing it before, unless your driving routes have changed. what is abnormal, and the sign of a failing battery is when the bars go up and down quickly from one end to the other.
how would you define quickly? edit: to clarify, i dont believe im experiencing that now, but would like to know what to watch out for in the future
it would just be much more noticeable. observe the current behavior. the meter changes as you drive one bar at a time, fairly slowly depending on the driving circumstances stances. that is how a healthy battery charges. when cell(s) get weak, (no dash light) you will notice it rising and falling more rapidly, and it will go all the way in each direction, instead of up a few, down a few, etc.
You could be seeing two possible things: 1) due to better cooling since duct repair, battery is being used more as determined by the battery's ECU seeing better, cooler temps. And 2) Because of heat (August, Texas) and your battery is getting old at 8 years, it has less capacity thus easier for it to reach full green bars than before.
Interesting observations, you clean the fan, tighten up the ductwork, and your battery seems to be happier. Maybe it's time I do another cleaning, it's been close to two years now. OTOH, I'm retired, and seriously into walkthedogism.
