My battery gauge no longer fills up!

[dagnarus75]

Hi guys... I'm a first time poster, long time lurker here at priuschat. I am posting now because I think I've run into my first prius problem...

I bought this car new almost 5 years ago next month. Whenever I have driven downhill for large periods of time (which is often, since I live in the rocky mountains!) I have always noticed that the battery gauge on the "info" screen fills all the way up. That is, until last weekend. I was driving downhill for about 30 minutes, clearly enough time for the battery to fill, yet the final bar on the info screen never showed up. It was always one bar away from the top.

Has anyone else had this happen? I took the car to the dealership and they say that the battery checked out fine - but that is definitely not consistent with this being the first time the car has exhibited the behaviour in 5 years. The extended warranty expires in 3 weeks, so I am hoping to get this resolved ASAP if it is a genuine problem. Thanks everyone!

[firepa63]

I think what you are seeing is normal. I never saw a "full" battery on my 04 and have not seen it on my 09. I do have to admit that I usually have the Consumption screen showing as the Energy screen is just eye candy and provides no real useful info.

The ICE will spin up to bleed off excessive charge on the traction battery. Possibly you viewed the screen just after a bleed-off.

[paprius4030]

I understand your worry, even with our "hills" my Prius reguarly fills up the screen with all green bars. I would inquire further at the dealer as how they tested the battery and make them give you a print out.

[narf]

It could also be weather related. The cold weather could be effecting the charge rate. I know for me the only time I see full green bars is when I'm heading down MAJOR hills, like the Eisenhower tunnel westbound downhill.

[Turbogizzmo]

I live in colorado too, on our trip to steamboat the hybrid batteries were drained the whole way up and then on the way back down from steamboat we didnt get the green FULL battery but did get this:




Then when driving back to Minnesota for my Grandfathers funeral I got a green battery around town multiple time, but never in Colorado.



Its a fun game to play but I think the Prius does whatever it wants.

[john1701a]

Lower temperatures bring on the green (7 or 8) bars more often.

And as I've observed, vehicle aging does too.

Now at 107,000 miles with the morning temp in the 40's, seeing more green is pretty obvious. The final 5 miles of my commute is a modest decent at 55 MPH to the river then a shallow hilly stretch of 50 MPH followed by 45 MPH. That seems to be the perfect formula for green appearing at mile 2 then retaining it all the way to my parking spot 3 miles later, now. It didn't use to be that way though. In fact, I didn't see the green last year until the final mile. Before then, almost never.
So, I'm curious to hear reports from others... especially when the reverse happens with owners that routine drive over mountains. It's basically flat here in Minnesota by comparison.

.

[stephen2002]

I don't live in Colorado but I've driven there a number of times. I noticed that in long downgrades if you put it in B mode before the battery fills it will really rev the engine and try to leave that top bar as buffer for when you need to use the brakes. If you listen carefully to the inverter whine you'll hear the pitch shift when you use the brakes going down a hill in B mode if there is battery capacity. If there isn't you don't hear the pitch shift. My assumption is that there is still a little bit of regen capacity left while it is spinning the engine full-out in B mode that it'll take advantage of until the battery is full.

Try one of those long hills without using B mode and the battery indicator should fill all of the way. Just be sure to shift it to B once it does so you don't overheat your brakes!

[delgesu]

FWIW, i've been driving my '09 for about a week now, and 1500miles, and i have yet to see the top bar light up...

[qbee42]

On downhills, speed is a big factor in relation to battery charge. When you descend a big hill at low speed (but still high enough for regenerative braking), it's easy to charge to full green. On a high speed descent, it's not so likely.

This is because of aerodynamic losses. At high speed, much of the recovered energy is used to push the car through the air. Looking at it another way, if you weren't descending a hill, you would be using a lot of gas just to move at that speed. The energy is used to push air, not charge the battery.

I saw this a lot on our recent trip out west. In Maple Canyon, it was a 2,000 foot descent to the basin floor, most of which was on a narrow gravel road. I would do the descent at 15 mph, and easily got full green bars every time, finishing the route with heavy engine braking.

On many of the mountain highway passes I could descend indefinitely without charging to full green, or would hit full green but need only light engine braking. In these cases we were doing 65 or 70 mph.

Tom

[dagnarus75]

Thanks everyone for your response!

firepa63 - I see it fill up all the time when I'm going down big hills, and didn't this time. That is my concern. When I see something all the time, then suddenly it's gone, the change is what is grabbing my attention.

paprius4030 - Hmm, good idea. I will ask for documentation if this continues. Since my warranty is up in 2 weeks, my main goal in getting it to the dealer was to get it on record that this problem occurred and was reported before the warranty expired. assuming of course that it is a problem!

narf and john1701a - That's certainly possible. I was at a much higher elevation that I usually am at, hence colder. I will check next time I am at my "usual" downhill full-green (which is also west of eisenhower tunnel) :-D if lower temps bring the green bars faster though, I would think it would refill faster at higher altitude, not slower, right? hmm.

qbee42 - hmm.. on this same note, I was probably driving slower than normal.. 25-30mph. This would go with that I should also have seen the green bars more quickly, assuming I was going fast enough for the regenerative effect.

Thanks again to all of you, I knew I could count on good info here. I will be keeping an eye on it on my next mountain trip and will post again if I get any more info.