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change battery charge levels?

Discussion in 'Gen 2 Prius Accessories & Modifications' started by johndgreene99, Mar 28, 2006.

  1. johndgreene99

    johndgreene99 New Member

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    i'm new to prius chat. i bought a 2006 prius about 2 months ago.

    i'm wondering if it's possible for the user (driver) to change the battery levels at which the prius uses the engine to charge the battery.

    i commute about 35 miles each way, and there is a big hill in the middle (about 1900 feet elevation). i find that the engine continues to charge the battery, keeping it at blue level during ascent. on the descent, the battery gets full. after the battery is full, i figure that it is no longer charging, so i am losing ability to store that energy. i would like to be able to discharge the battery more on the ascent so that there is more headroom available to charge it on the descent.

    does anyone know of a way to affect the charge kick-in level?

    thanks
    john g
     
    #1 johndgreene99, Mar 28, 2006
  2. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    nope... preventing user settable options in this area is the ONLY way Toyota would provide as long a warantee.

    to put it in perspective. if properly maintained, a cellphone battery should last 3-5 years. most last less than 2. that is because we control the recharging.
     
    #2 DaveinOlyWA, Mar 28, 2006
  3. jeneric

    jeneric New Member

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    This is info, not advise, probably not even good info, but maybe you can shed more light on it with your daily commute. You can drain your battery by accelerating hard enough, so it can't charge the battery, and when you start going too fast, shift to Neutral. When you start going too slow, repeat acceleration. The hard acceleration probably wastes more energy than you're gaining. Plus it's probably not the safest way to drive.

    Another option would be to use EV mode near the top. You could figure out how to time it, so you know exactly how far it will get you to the summit. Honestly, there's not a whole lot of juice to get you very far uphill in the battery, so it's probably better to just not worry about it.
     
    #3 jeneric, Mar 28, 2006
  4. johndgreene99

    johndgreene99 New Member

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    <div class='quotetop'>QUOTE(johndgreene99 @ Mar 28 2006, 09:19 AM) [snapback]231410[/snapback]</div>
    i read the replies to my post. thanks for the information. i got 2 main points:

    1. it is not possible for user to change battery charge kick in level. it would reduce battery life if people were allowed to charge and discharge the battery at will.
    2. the overall battery capacity is pretty small anyway, so a little bit of hill energy is not that big an opportunity.

    i have not made the EV change to my car yet. if i do, i'll give EV mode a try to keep charging minimized during ascent (depending on traffic speed at that time - traffic on ascent is often faster than 34mph). perhaps that will allow me to get a little more charge on the descent. since most of my miles are on the hill pattern, it seems to me it would improve my mileage slightly.

    thx
    j

    <div class='quotetop'>QUOTE(johndgreene99 @ Apr 1 2006, 02:53 PM) [snapback]233503[/snapback]</div>

    just one other note: i do almost all my driving alone, in the hill commute pattern. i'm getting 44.5mpg, which i found a little disappointing. i think part of the reason for the somewhat low mileage is the hill. (not sure about that, but a possibility). i hit some traffic, but a lot of my commute is at 50-65mph. i try to use the mpg meter to modify my driving to get decent mileage - i'm not lead-footing it by any means. my tires are at correct pressure; at least i don't have any tire pressure warning. i don't run 44psi - i have them at more like 35, where they were when i took delivery from the dealer.

    thanks again
    j
     
    #4 johndgreene99, Apr 1, 2006
  5. darelldd

    darelldd Prius is our Gas Guzzler

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    <div class='quotetop'>QUOTE(johndgreene99 @ Apr 1 2006, 03:00 PM) [snapback]233503[/snapback]</div>
    For a hilly commute, I think 45mpg is excellent!

    As far as I know, the tire pressure warning only happens when one (or more) tires show a pressure significantly different from the others. I think if you set them all at 20psi, you still would not get a warning. Try airing them up to ~40psi and see if it helps your mileage. It will certainly help the handling. Some find the ride too harsh, but not me!
     
    #5 darelldd, Apr 1, 2006
  6. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    tire pressure increases to 42/40 will give you another 2-4 mpg.

    although the "max" tire pressure is listed at 44 psi , that provides a safety fudge factor of at LEAST 50% under normal driving conditions. tire companies would have been sued into bankruptcy years ago had they not engineered that margin into their product.

    would i recomend as much as 66 psi?? well no, but that would be safe under relatively benign to good driving conditions. for your legal protection, 44 is as high as i would go...keep in mind that would be cold tire pressure. obviously in the summer, the tire pressure would go up from there. its sometimes hard to resist lowering the pressure on those hot summer days, but that is not recommended or necessary
     
    #6 DaveinOlyWA, Apr 2, 2006
  7. 8AA

    8AA Active Member

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    I tried setting the tires at 42/40 for awhile and found the ride a little harsh. I backed it down to 37/35 and found the ride and handling to be improved and not a significant reduction in mpg.

    One thing you might try when going up hills is to try to achieve "deadband" where no arrows are going to or from the battery. Power generated by MG1 goes directly to MG2 without being converted from AC to DC and then back to AC. It's not a huge difference, but there is some improvement in efficiency.
     
    #7 8AA, Apr 5, 2006
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