Battery life considerations

[tekn0wledg]

I've read numerous posts regarding battery life considerations, and I searched for information on this topic, but have not found the answer I am looking for as of yet. If I missed a thread with this info, I apologize ahead of time.

My question stems from my latest driving route which affords me very good FE [about 70-75mpg routinely] over 16.1 miles. During this route I am able to P&G for most of the trip since speeds are between 35-40 for about 10 miles, and 45 for about 5miles.

During times where I am able to P&G for long distances, there are situations where I can accelerate using the battery only to get up to my next pulse speed. When I am able to do this, my battery bars drop down from 6-7 to about 3-4.

My question is, should I avoid using battery only to accelerate in these instances to prolong battery life? Or would this only be a concern if dropping the energy bars to 1-2 routinely?

I am asking because I really enjoy this new route, and I am fairly certain I can get my FE to above 80mpg, but I've been hesitant to abuse the battery privilege at this point.

Any comments are appreciated.

[etyler88]

Don't worry about it. Toyota limits the battery capacity usage, the MFD display is not the actual battery capacity. Let the computer do its thing, alot of R&D has already figured it out. P&G to your heart's delight.

[bwilson4web]

<div class='quotetop'>QUOTE(tekn0wledg @ Aug 20 2007, 08:20 AM) [snapback]499075[/snapback]</div>

I've read numerous posts regarding battery life considerations, and I searched for information on this topic, but have not found the answer . . . [/b]

It is an area where we don't have a lot of factual information. Most battery life studies concentrate on peak and minimum charging. Some of the best applied information is available with the electric, RC modelers who regularly run from peak to minimum charge. But our Prius is different.

The battery and hybrid ECUs keep the battery between 40-80%, a very nice place to be for long battery life. To the best of my knowledge, no one outside of Toyota, has done a life-cycle analysis of charging and discharging versus cell life in the 40-80% range.

<div class='quotetop'>QUOTE(tekn0wledg @ Aug 20 2007, 08:20 AM) [snapback]499075[/snapback]</div>

My question is, should I avoid using battery only to accelerate in these instances to prolong battery life? Or would this only be a concern if dropping the energy bars to 1-2 routinely?

I am asking because I really enjoy this new route, and I am fairly certain I can get my FE to above 80mpg, but I've been hesitant to abuse the battery privilege at this point.

Any comments are appreciated.
[/b]

As a general rule, I recommend:

1) avoiding heavy currents - this leads to heating the cells and this can drive off the electrolyte
2) avoid high temperatures - this lowers the amount of current needed to drive off the electrolyte

However, the Prius has an active temperature management system including a battery fan. So as long as these systems are intact and not stressed such as parking in the sun, they should last a very long time.

One local Prius owner had the battery pack replaced just within the warranty, 98,000 miles. He lives on the other side of Monte Santo Mountain, a 500 ft. hill, in North Alabama and commutes over it each workday. Three times I've met him at his work and each time, his car was parked in the middle of the parking lot, away from any shade, and his paint shows sun fading damage. IMHO, the problem is heat.

Bob Wilson

[tekn0wledg]

Thanks Bob.

I do park outside in a parking lot, but I generally park under a small tree which provides some relief from the sun. I also use a sunshade, so it's much cooler inside the car than outside.

[fred s]

I think to answer this question, you have to look at the most common answer: Just drive it like a normal car. The engineers have spent a lot of time on this, so you should feel confident that you won't mess it up by driving it how you are.

[brick]

Generally speaking, using measurable battery power for propulsion isn't as efficient as letting the gas engine kick in for a pulse. For that reason alone I would not recommend draining it down to get to that next glide. Of course that's a guideline, not a rule.

[tekn0wledg]

<div class='quotetop'>QUOTE(brick @ Aug 20 2007, 10:29 AM) [snapback]499106[/snapback]</div>

Generally speaking, using measurable battery power for propulsion isn't as efficient as letting the gas engine kick in for a pulse. For that reason alone I would not recommend draining it down to get to that next glide. Of course that's a guideline, not a rule.
[/b]

Well basically it's not so much using battery to get up to speed as it is using battery to crest over a couple of small hills after a long glide. It's basically maintaining the glide a bit longer instead of dropping to a lower than desirable speed.

This road is fairly level with the occasional small hills. So where appropriate I have been using just a touch of battery to get up and over the hill and into a glide again.

Towards the end of the route I have the ability to regen most of bars in a downhill section, so I'm usually sitting at 6 bars or so when I get home for the evening.

[Presto]

<div class='quotetop'>QUOTE(bwilson4web @ Aug 20 2007, 06:41 AM) [snapback]499082[/snapback]</div>

One local Prius owner had the battery pack replaced just within the warranty, 98,000 miles. He lives on the other side of Monte Santo Mountain, a 500 ft. hill, in North Alabama and commutes over it each workday. Three times I've met him at his work and each time, his car was parked in the middle of the parking lot, away from any shade, and his paint shows sun fading damage. IMHO, the problem is heat.

[/b]

My guess would have to be the heat that killed his batteries, especially if the office is located at the bottom of the hill. After a hard session of regen, the batteries may still be on the upward temperature rise when the car is parked and shut off. The battery fan really needs to keep working for a time period after the car is shut off.