Battery failure early signs

Beside the battery issues, how are your mpg's?

 

Sounds like the battery is going south or maybe you lost the Inverter Coolant pump. See if you have any turbulence in the Inverter Coolant reservoir when in ready. Lots of Youtube's about it.

 

I have a similar problem.

I'm still getting same mpg. 46mpg 95% freeway.

Is the inverter coolant pump the one on recall?

 

Yes. Check for turbulence in the I reservoir when in ready. Many Youtubes about it.

 

I have a ScanGauge II in my Prius, so I rarely if ever glance at that screen on my MFD anymore, but when I have, it does that normally. My car had 27,000 miles on it when I bought it and it's been working perfectly ever since-- I've put nearly 40,000 miles on it since I bought it so far. That behavior on the screen is normal if I'm understanding your description correctly. As for charging to 7-8 bars, mine doesn't usually do that, but I live in a hilly area so I'm constantly climbing and descending. When I took it to Phoenix, it would hit 7-8 bars pretty easily whereas it was all but impossible to do it where I live in Colorado unless I was on a longer downhill while gently braking to a stop.

 

I agree with babybird. The frequent charge reversal is fairly common under sustained driving in flat conditions. The fact is that the HV battery just isn't doing a whole lot under these conditions, and what small current it is either sourcing or absorbing can chop and change direction fairly quickly.

I'd be more concerned about the rapid changes in SOC. This to me is a sign of the HV battery weakening. The main question is does this just represent a loss of capacity (A-hrs) of the battery, or is it something more serious like a badly degraded cell or cells. If you get badly degraded cells with either high resistance or short circuit, then I think it throws a code pretty quickly and the battery is toast. If it's just a gradual decline in A-hrs, without a significant loss of voltage or increase in resistance, then I think the computer just accepts it and everything is business as usual, even if the capacity goes to less than 50% of new.

Personally my 2005 also seems to have noticeably less battery capacity than it once had (particularly in that it hits 8 green SOC more easily), but otherwise gets good MPG and drives well. Here's some coping strategies for a Prius with somewhat reduced battery capacity.

1. Try to avoid regen to 8 bars if possible. I use "B" mode a bit more often now to try an avoid filling the battery.

2. Try to keep the battery at 5 to 7 bars most of the time if you can. For example, if "gliding" then perhaps try to engage the ICE just a little sooner before you lose too many bars.

3. This one I highly recommend. When you first start a trip and the engine is cold, it takes a lot of power from the HV battery (in preference to the engine). This can easily make your SOC fall to 2 or 3 bars pretty rapidly in the first few minutes. I find that allowing the Prius to warm up for just 45 to 50 seconds (engine running and Prius in "P") makes a huge difference to the problem.

 

Instant solution for your concerns.

Change the MFD screen to fuel consumption for five minute intervals and keep it there.
It has an instantaneous fuel economy bar gauge on the far right side to accompany the five minute average mpg. You really don't need to know more than that.

And if you're constantly looking over at the MFD to check the SOC, your eyes are not on the road where they ought to be.

Toyota made a mistake adding the SOC screen. It's like Maggie Simpson turning
her toy steering wheel next to Marge. The Prius battery management is automatic.
You have virtually no control over the SOC except when engaging B mode when
going downhill.

 

As other's have pointed out, the traction battery and the systems that work with it pretty much take care of themselves. In your case, with the age of your car and the amount of miles it really is best guess as to when the traction battery might fail. You can pay Toyota to test the battery for you, or you can save that money along with the saving's you are realizing today each time you fill up towards any future repairs.

Any used car as well as any new car will eventually break down. It is a fact of life and as long as you own a car you will need to make some sort of repair. If I were in your shoes, I would not worry about it. If you are concerned, then set some funds aside as I suggested above and keep on driving the Prius. A lot of people worry about the traction battery, however the truth is there are components in the Prius that are far more expensive than the battery, and you rarely hear folks being concerned about them.

If you are unfortunate and do suffer a battery failure, there are a lot of options available for you. The battery could be rebuilt, repaired, or even replaced.

HowStuffWorks "Hybrid Battery Replacement Cost"

Ron

 

No don't get me wrong, there definitely are patterns to look for, and things to look out for concerning deteriorating battery capacity. It's just the part about driving on flat road at constant speed which is not a very good indicator of anything in particular (at least not that I know of).

I'm much more interested in the part you mentioned about dropping from 6 bars to 3 almost instantly! Myself and one other member here (priuscamper) have noticed exactly this issue and it definitely appears to be a sign of battery deterioration (or loss of capacity). We have noticed in particular that this behavior doesn't always happen, but when it does it always happens after the SOC is coming back down after being max'ed out at 8 green. I'd be really interested if you could confirm that this is similar to what you're seeing Extronic.

Just google earthed it. Wow yes that's a bit of a killer hill, about 800' of elevation in 2 miles at presumably fast freeway speeds. I'm not sure how flexible you are on speed through there Extronic, but if you are able to drive without cruise control and just let it naturally slow down a bit on the steep sections and speed up a bit on the not so steep parts, then this style of driving can help a lot.