My battery still stays too full

Considering that your car has to go up & down the SF hills every day, 49 mpg sounds pretty good to me.

I live at 1,100 ft elevation and commute to sealevel. I usually log mid-40s mpg but this includes substantial carpool lane travel at the prevailing speed, which is usually ~75 mph or so.

I also see eight green bars on the descent. Regarding the traction battery SOC, it is what it is, you can't really control it, and I suggest that you not worry about it.

If you want to see two purple bars, all you have to do is park your car for a while, leaving the air conditioner on.

 

I've only had my car for a week but so far, I'm seeing the same thing you are. At times, it seems like the gas engine starts and recharges the battery when it's two or three bars down from the top.

 

I too have a problem with my new 2008 Prius. It likes to keep the battery TOO LOW. Different than you, I've been at two bars a couple times and I ONCE got 6 bars or was it 5 bars, usually it hovers around 3-4 bars.

Lucky you.

Actually, I have the Hybrid lite, you have the Hybrid Untouchable.

I drive in an urban area with a long long slight incline northward.

Who needs the empty battery?, you're at the top of a long downhill with full power, what more should you ask for?

I fully believe if you run your car in my environment, you'd hit two bars eventually, AND I only get 46.4mpg and you are driving up hills which take more gas.

I think the problem you are requesting an answer for is merely perception. You expect it one way, the car gives another.
Otherwise, I believe there is nothing wrong with either of our cars.

ZC1

 

There are lots of reasons for the engine starting when stopped.
The most obvious ones are:
- When it's cold outside, and you have the heater running. The car does not like the coolant dropping below ~140 degF, so it'll burn fuel to get back to warm state.
- you're in stage 1, where the engine will run to heat up the cat, as well as other parts.
--It is possible for the engine to shut off if you 'idle' it for too long, it will still be in stage 1 when you push on the gas.
- You're in inspection mode.. Don't do this..
- The rate of acceleration is greater than what the battery can do alone.

-There is a current limit that is set by several parameters (SOC, temperature, etc.) Under some conditions (i.e. >120degF) the battery _DISCHARGE_ limit is quite low. I have seen this limit down to ~20A, even when the SOC was in the green region. Which is not much, for the prius at least..
Note that the car feels horrible in this state...

- When the battery is comfy, it can push ~125A, you can usually tell when the battery is comfortable when you're comfortable..

 

Why would Toyota assume that the computer can do it better than a human? Could it be that the algorithm-preferred 6 bar state is better for the battery?

 

I suspect the ICE spins up just to warm the catalytic converter. In my daily commute I always have one crappy 5 minute period. I'm seeing more bars more often when the temps rise and I experienced a full battery twice coming home from western PA. Nothing like going down a mountain to boost FE.

 

Keep in mind that the most efficient energy the Prius uses is that which comes directly from the ICE. Although taking excess energy, putting it in the battery, and using it later is better than dissipating it as heat in brake pads, or wasting it idling - it is still less efficient than energy taken directly from the ICE for immediate propulsion, which doesn't experience the inefficiencies from the extra energy conversions.

I think this is why my Prius seems to want to keep the SOC around 6 bars. But there are predictable exceptions:
1.) During the warm-up the Prius will "baby" the ICE and pull energy from the battery until the ICE can warm-up to reach optimum efficiency for both emissions and fuel consumption. Typically I'll see the SOC drop from the nominal 6 bars to 4 or 3 bars until it is warmed up, and begins to build charge back up to 6 bars.
2.) When coming down from highway speeds to local traffic some of the kinetic energy is packed away in the battery. I'm typically at 7 or maybe 8 bars when I'm stopped at the traffic light at the end of the exit ramp.
3.) Coasting or braking during long downhills will pack away enough energy in the battery to reach 7 or 8 bars.
4.) In very cold weather the ICE will run just to keep it at a sufficiently warm operating temperature for emissions efficiency (and to provide heat to the cabin, if you're calling for it - remember - when you heat the cabin, you cool the engine). Some of the energy from all that extra ICE run time goes into the battery. So, it is not uncommon to see 8 bars under normal driving conditions in really cold temperatures. You'll notice this because if you're stopped at traffic lights in very cold weather, the engine will still be running, where it would likely shut off in warmer weather. I've found that doing the grill block thing really helps reduce this.
5.) Driving on flat local roads at fairly constant low speeds (<42 mph), with minimal stopping and avoiding acceleration will allow the ICE to shut down for extended periods. With a light foot on the gas I've found the SOC can drop to 4 or even 3 bars before the ICE will start up.
6.) When parked with the car ON, my Prius will drain the battery to 2 bars before it restarts the ICE.

It sounds to me like your Prius could be operating normally. But I don't know. Do the situations described above match your experience?

 

It's the temperate climate and the hills, echocanyon. I feel your pain. The hills are steep enough you have to run the ICE to climb them, charging the HV battery, going down the other side you have to control your speed, charging the HV battery. It's cool enough so you don't have to run the AC much, so little discharging the HV battery. When it's cooler, the ICE runs, charging the HV battery. I'm sure you've experienced charge dumping, where the ICE cycles on and off without fuel just to discharge the HV battery.

Your milage is fine. You can try creeping up the hills, trying to keep all the ICE power away from charging the HV battery, but you go really slow up a steep hill. I envy the FL and TX drivers their warm, flat terrain, except I'd have to live in FL or TX (no offense guys, I love to visit.)

 

After a couple of months of driving the Prius I am satisfied anytime my first 5 minutes is over 25 mpg. The next 5 it usually 50 and up depending on traffic.

For the most part I seem to do best when I "just drive it".

Bob

 

Bill,

No offense taken. (Don't tell anyone I said this, but if it wasn't for the climate, Florida would be pretty far down on my list of places to live) Oops!

I can't speak for TX, but here in Florida we LOVE visitors. All we ask is that you bring, (and spend), lots of money.

Bob

 

ZC1 – I had the same issue/concern with my brand-new ’07 last year. I was very concerned because I seemed to see purple all the time. It was rare that I would get into the “blue zone†and I never saw those green bars. This lasted for almost two months of regular driving. It really bothered me, because I was focused on building up SOC so I could run on, essentially, EV mode. Of course I now know this is not a valid objective if the idea is to maximize MPGs and minimize energy usage.

I hope there is some comfort to you in that my Prius eventually changed. I now regularly see the whole spectrum of colors in the SOC display. I also have increased my MPGs. Some of the increase came from learning to drive the car better. Some also came from passing the “break-in†period.

Don’t worry much about getting “only†46.4 mpg! I imagine that number will be at least 2-3 mpgs higher by summer’s end. Warmer weather, experience and tread wear all account for good increases in MPGs.

Here, I think you are entirely correct and offer good counsel. Your car is just fine, and you’ll see continuing MPG improvement this summer!

 

I've never seen the pink bars. I have seen all green (descending mountain passes and a few times in the city) . Pearl stays mostly at three or four bars down (blue) in the city and on the highway. Considering your driving environment it sounds like your car is doing just fine. 49 MPG is not bad. I just did a 650 km trip and averaged 50 MPG US, cruising speed was 105 km/hr, or about 66 MPH. Mostly small hills or level, ambient temps. 75 F (with three people in the car).

 

My initial post, taken as a whole, was merely a contrasting (but truthful) argument to show that perception is really the issue in this case, not a state of charge (SOC) problem.

Sometimes paralysis by analysis sets in, or at least some unknown fear, which can lead to untenable conclusions.

ZC1

 

A couple of notes as I have observed. If the SOC tends to be "too high" or "too low" according to whatever our philosophy is on how the Prius software controls the battery managment and there is some variability +/- a bar or two, then the net result would be that you are using as much energy as you store away. If the bars never change, then maybe your not charging nor discharging the battery at all and this may need some attention.

If you worried about having too much charge in the battery when cresting a hill, try warp stealth down the other side, if speed permits, to use some of those electrons and NO gas.

My goal is not to only stash away electrons when the opportunity presents itself, but to use them as they accumulate. Stealth and warp stealth works well to obtain this goal.

My personal driving habits have changed since the purchase of my Prius as I have learned how to drive it. I have a 35 mile commute through the rolling hills of WV and have been averaging 60mpg the last couple of months. Not hypermiler status but not bad for a mostly highway commute.

Kaos1