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Battery level always very high

Discussion in 'Newbie Forum' started by Frayadjacent, Mar 25, 2009.

  1. Frayadjacent

    Frayadjacent Resident Conservative

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    Howdy, y'all. Bought a new 09 base Prius this past Saturday and already have over 300 miles on it. I've noticed that the battery level has never gone below about three bars from full, which makes me think the car is being very aggressive at keeping the battery charged, rather than being aggressive with electrical assist.

    My driving has been considerably long trips (usually at least 20 miles one way) and I haven't used the AC much yet, but I do usually accelerate 'briskly' to get up to speed and then cruise, which worked well in the Insight I had a few years ago. I figure the car is getting into S4 well within my commutes.

    Is this behavior (the battery being kept very full) normal, or normal for a 'young' Prius?
     
  2. paprius4030

    paprius4030 My first Prius

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    Yeah it's normal. My battery is usually always in the green especially during highway driving. My normal driving it's usually either high blue or in the green
     
  3. Frayadjacent

    Frayadjacent Resident Conservative

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    Hmm... it would seem to me that if it's always very high, then the system is not using it enough to alleviate using the engine. I figure it would want to target the state of charge level to remain around two thirds (of the usable range of the battery, not the total - I am aware that the battery is utilized in a restricted range of charge) so that it could capture energy during regenerative braking, and use more electrical energy for acceleration.

    Maybe I'll see the battery drained more during the hot months? I hear the AC is VERY good... and, well, I'm in Texas. I WILL be putting it to the test!
     
  4. JimboK

    JimboK One owner, low mileage

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    Actually the car aims for 60% (six blue bars) as the optimal state of charge. The battery indicator shows from 40% (no bars) to 80% (all eight bars) -- pretty much the full operational range of what the car's battery control algorithm allows, as this graphic shows:

    [​IMG]

    So to echo Paprius, it's perfectly normal.

    EDIT: Oh and yes, the AC will pull it down (and drop your fuel economy) considerably at slower speeds.
     
  5. Frayadjacent

    Frayadjacent Resident Conservative

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    Thanks for posting the graph, it's very informative. I read it as saying that the charge indicator is not linear. So the state may be draining more, but it's in the larger areas of the graph above.

    I am curious to see how it does when it really starts getting hot out here! My windows are not tinted yet... so I'll have to do that as well. I've been pretty religious about doing that on my previous cars, and it really helps in the hot sun. I do park in the garage at home and in a parking garage at work, so that mitigates the heat quite a bit.
     
  6. qbee42

    qbee42 My other car is a boat

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    Spend some time reading some of the threads on this site and it will help you understand how the hybrid system works. One of the counter-intuitive things is that the more you use the battery, the worse your mileage. Under ideal conditions the battery would never have to charge or discharge. Do a little reading and it will make more sense.

    Tom
     
  7. dogfriend

    dogfriend Human - Animal Hybrid

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    If you really want to see the purple bars, park the car with the AC on and leave the car in "Ready". Depending on the outside temp and sun load, the AC will pull current from the battery at a pretty high rate to keep the car cool. In Texas heat, you should see those purple bars within 15 min or less. Once the SOC gets down into that range, the ICE will start and run for a few minutes, then shut off, then run for a few minutes, then shut off...............
     
  8. JimboK

    JimboK One owner, low mileage

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    Window tinting was one of the first mods to my car. But then I don't have garages to routinely park in. Even if I did, I would have the tinting. Besides the cooler cabin, I like the added privacy.

    At the peak of a mid-Atlantic summer, cabin temperatures after a day-long park in the sun can push the hybrid battery temperature close to or even above 100F. Running the AC heats it even more -- short term, at least, until cabin temperatures start to cool it, though that's a rather slow process. With heat as an enemy of battery life and function (and with the car's ability to monitor battery temp), the car begins to take steps to conserve battery power at a battery temp of 104F or so. With that comes a modest reduction in fuel economy as the engine runs at times when it otherwise wouldn't.

    Therefore, I avoid parking in the summer sun as much as possible. At work, I have my favorite summertime parking place that's shaded most of the afternoon, and I get to the office early enough to claim it. I always look for shaded spots when I go shopping, even if it means walking further (the exercise doesn't hurt, either). I keep my front windows cracked to release a little heat, and I recently added side deflectors to them so I wouldn't have to worry about sprinting to the car to close them for an unexpected rain shower.
     
  9. Frayadjacent

    Frayadjacent Resident Conservative

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    Thanks for the feedback gentlemen. I am still learning how the car operates, I just figured it would rely more heavily on the electric system. Maybe it is, but since the battery indicator isn't quite linear, I'm just not seeing it as much. Combined with the fact that it has to recharge itself...

    I'm happy that my MFD economy indicator (which didn't reset when I filled up the first time) is right at 46mpg. I'm getting the EPA estimated fuel economy on the second tank, which gives me confidence that when the car is fully broken in, I'll handily beat it.

    It's also not yet summer here, so I will definitely be seeing how the AC affects the whole system. Window tint will be a 'must', even though I park in a garage. Like JimboK said, the privacy is also welcome. (helps avoid thefts, too. Thieves are less likely to break in when they can't see anything to steal) I will also look into getting the deflectors/vent visors. I like to keep a window cracked to let hot air escape. I did experiments with a thermometer in a couple previous cars during summer - checking temperature before window tint, with/without a front windscreen shade - and learned that tint and a front windscreen shade DEFINITELY help keep the car cooler.

    I'm reading around the forums and learning more and more every day. Everyone seems very helpful and supportive, so I'm glad to be here.
     
  10. EZW1

    EZW1 Active Member

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    I have a comment here that is a bit wordy but may explain what Frayadjacent has been experiencing - and this is based on my experiences with my '09.

    It seems the system as some kind of memory that remembers your driving habits. I've noticed if I drive very aggressively for a few miles then try to get it to go into Stage 4, it nearly refuses.

    But if I drive somewhat passively, then it easily goes into Stage 4 and wants to stay there. It fill fire off the engine only when the battery charge gets low. One caveat: when in Stage 4 you have to be light-footed on the pedal to keep it there or it will jump back into Stage 3 thinking you want more power than it wants to deliver.

    Now, this is not to say you cannot maintain speed or even gently accelerate while in Stage 4... you can. I do it all the time.

    This car is extremely intelligent. I've noticed at times while rolling along in Stage 4 at 42mph and the road inclines, the car will fire off the engine to help the climb!

    So, this all means that those that have a problem getting to, or stanying in stage 4 might want to access the weight of their foot. Currently, in an average 75-80 degree day, I'm easily getting 58mpg! As a matter of fact, on the way to work this morning, just before I shut my Pri down I noticed 58.4mpg.

    Hope this helps