6 bars drops to 1 then normal for the remainder of the day. HV battery on the way out?

Let's cut to the chase: 2008 Prius with 180,000 miles give or take. Upon start up, HV battery showing 75% charge (6 bars) but discharges as I am driving. The indicator drops as low as 1 purple bar before beginning to charge again. Once the HV battery is back up to 6 or 7 bars, it stays the same for the remainder of the day. The next morning, the same situation and so on. Temperatures during the day have been in the high 60s low 70s and dip to the 40s at night. This happened a few times last fall but resolved itself once the cold weather set in. Now that the weather is warming up, this problem has returned. No codes or lights on dash.

What I need to know is this: Does the HV battery indicator EVER lose all the bars (empty)? Does the fan ALWAYS come on in the rear prior to failure (mine has not come on yet)? I realize that the battery can decide to die today or last another year with the same symptoms.

I would like to hear from any owners who experienced similar situations. Should I price shop the local dealerships for a battery? What have YOU done to resolve this problem? What is Toyota installing in the Gen 2s?

 

Haven't cleaned the cooling fan since I bought the car in March 2013. No pets and no kids in the car, windows rarely opened. Previous owner did have pets but the car was not trashed. The only difference between now and a few weeks ago (when we were still getting snow) is that I no longer allow the car to warm up with the heater and defroster "on" before leaving in the morning. I may try allowing a warm up period to see if there are any changes. There is no decrease in mileage that I can see. Is there a correlation between a/c output and a failing HV battery? I was annoyed on one particularly warm day last week when the temperature got up to 82 degrees and it seemed that the a/c was barely putting out cold air. The fan was on high but acted as if it was on a low setting...

 

I see that after the rebuild, you went with a new Toyota battery in July 2017. Did you do the install or did you have the dealership install it? If I had the time, I would mess with the battery myself but right now my free time is limited due to my house renovation. I do have another vehicle to keep me going but it guzzles much more gas than the '08! I have a 2005 (original owner) that has 323,000+ miles on the original hybrid battery with no maintenance at all over the years. Unfortunately, not all of these batteries last as long. Luck of the draw, I guess.

 

Ok. I have read more than enough threads on the Gen 2s. Some have said that allowing the car to warm up before initial take off in the morning should help. I experimented and did this. The HV battery responds as it should. No more purple bars and stays between 4 and 6 most of the time. Normal charge and discharge and is getting an average of 52.2 miles a gallon since my last fill up. Is this only a temporary solution?

 

That's exactly what I have read. Tried it now for the past few days and the problem has disappeared for now. I'd like to match the reliability that we're getting with our '05 which has over 324,000 miles on the original engine, transmission, and HV battery!