battery charge NEVER gets to the top

If you want to see eight green bars, the best way is to glide down a mountain road, 1,000 foot elevation drop or more. Pulse and glide will not help to increase battery charge.

 

Completely normal. Don't worry about it. Approx. 60% SOC (state of charge), yielding blue bars, is the control system's target. You will likely only ever see full green after a long downhill regen., which then precipitates less regen, more mechanical friction braking, and undesirable ICE (internal combustion engine) turnover to discharge the battery. Full green doesn't mean you're doing better, so don't try to achieve it. 60% SOC is the point at which battery life asymtotically approaches infinity, which is wonderful.
In general, don't worry about the battery SOC. Remember, the most efficient Prius operation includes driving for no electrical flow to or from the battery.

 

You don't want to see the battery full. It usually means your wasting tons of energy if you do.

 

The Prius battery control works hard to keep the state of charge (SOC) in the middle. Being in the middle allows power for electric operation, while still allowing room for regenerative braking.

Tom

 

If you're intent on seeing it full, take a long highway cruise at about 50mph, holding a constant amount of pressure on the accelerator. Allow your speed to vary with the grade, but keep a constant amount of gas on. That got me a full charge after only about ten miles.

But yes, as the other posters say, it's fairly wasteful to burn a bunch of gas only to stick the energy in the battery.

 

I think it's normal. Only once have I seen mine go all green, and I can't remember what the conditions were when it happened. I was shocked, and kept looking at it to make sure I wasn't seeing things! I've had mine since May with about 6,000 miles on it now.

 

Uhh.. If you REALLY want to see it all-green... floor the brakes, and put the other foot on the gas and push it to mid-position.

This'll then "force-charge" the battery....

Disclamer: Do so at your OWN RISK!!! DANGER!!! If you force charge it too long, you may DAMAGE/DESTROY your battery.

 

With respect to the Prius battery, green is not "good"--but relax, it isn't bad either. It is not a target and instead is a state that the Prius controller will try to move away from. Green means a state of charge (SOC) at the high end of the control range. Purple/pink means a state of charge at the low end of the control range. Blue is the "happy" range in the middle for the battery; and the ECU adjusts to keep the charge at the top blue bar or the blue one just below. Blue is good because that is the range of SOC where the battery should have its longest service life. Toyota's color choice of green for high (but safe) charge levels is unfortunate and counterintuitive. Most of us have grown up in a world where green represents a "go/good" state for equipment and it is naturally the level we will guide toward unless instructed otherwise. It is my opinion that the blue should be green with other choices for either end.

I can get a green charge very easily stopping at the base of a long downhill from highway speeds. I also seem to get them more during cold weather when warming up since the ICE is running when it really isn't needed.

There are some positives to driving with the first green bar lit. It is easier to start mild acceleration without the engine starting, etc. and this is useful in short moves in traffic where the ICE would be doing little more than idling for a few seconds then shutting down again. It also makes it easier to maintain an arrow free glide as the deadband is wider at higher states of charge. This is one of the hardest things to become accustomed to/factor in about the hybrid synergy drive: the system responds far differently to high and low states of charge so the same throttle position does many different things depending on a host of factors. It changes what the throttle is doing in order to maintain a target charge, coolant temps, etc. I like the "feel" of the green bar throttle bands best as this range allows me to better manipulate whether the engine is on or off. (However, I realize it is probably a zero sum game as I'm slowly using the excess charge, but it is more psychologically satisfying because I feel like I'm in control and can keep the engine off longer while the extra charge is utilized.)

I suspect that dipping into the purple/pink bands is somewhat harder on the battery than either of the green bands. My reasoning is that the controller is biased towards the upper blue bands and is eager to recharge the pack whenever the lower blue bands are reached.

Whether in the high or low safe range on the state of charge it is my impression that batteries suffer most when the current flow in or out is greatest. But perhaps that is incorrect.

 

Yeah, what they said
If I get all green (happens with some frequency in cold Vermont winters), I try to get some distance on electric only. I can make the 'generally flat or downhill and mostly 30 MPH or under' mile from the Interstate to my house and still have 6 blue when I arrive.

 

It might seem a paradox, but the *less* you can use the battery the better the MPGs will be. All conversions of energy from one form to another are less than perfectly efficient (that is, some of the energy is unavoidably turned into heat and lost), and batteries are especially poor.

Good MPG short-path zen:
- Accelerate briskly (this uses the engine most efficiently)
- Drive as though you have no brakes.
- Gliding (no arrows on the "Energy" display) is better than coasting, coasting is better than braking, braking is better than stopping.

Use this zen in moderation, to avoid enraging drivers behind you :_>

 

Headlights make little if any difference, the battery is performing correctly, don't worry about it. I suspect you have no big hills there.

 

Yes, I do that too. It really helps on short trips where the ICE runs needlessly in the first half or with certain hill traffic combinations. It appears to be more efficient than losing the ability to recover charge on following starts because of the same cycle.

About a 2% mileage hit in slow, in town traffic, probably only 0.5% on open highway by my calcs.

 

The drive system on the Prius simulates engine drag when you take your foot off of the accelerator pedal. This simulated drag is really light regenerative braking. Gliding, on the other hand, is coasting without the simulated drag. To get this, you add just enough accelerator to eliminate the simulated drag.

Tom

 

Took me over a year before I saw the battery full! During a long trip downhill in North Carolina!

 

To amplify on gliding, at low speeds the most efficient operation is a "no arrows glide." The arrows represent current (electrical) or power (gas engine). No arrows does not necessarily mean no current, although for our purposes it is pragmatic to think of it that way. Those with Scan gauges report that there is some current going from the traction battery to the electric motor even when no arrows are displayed in the glide (you can feel a slight acceleration at times in a no arrow glide, and it changes with pedal depression across a brief range).

The key thing to remember is that in a no arrows glide state there is minimal power conversion to or from the battery and essentially none from the engine. Minimizing power conversions is the most efficient way to operate the vehicle. Pulse and glide techniques do this by operating the ICE briefly to accelerate in an efficient engine operating range, then going to a no arrows glide with engine off. In this way transfers back and forth to the battery pack are minimized.

When you try to coast in the Prius by lifting off the pedal completely, a small amount of regenerative braking begins. This regeneration is great when you are approaching a stop, but bad if you want to truly coast (because a portion of the energy is lost in the conversion to the battery pack, and again later when it comes back from the battery to the drive.) Reapplying just enough accelerator (with the ICE now off) will stop the regeneration and switch to the no arrows glide. When the ratio of distance covered in pulse vs. glide is high enough the average fuel economy can be tremendous.

 

Are you going to change oil at 3K? or just the first change?

 

Which, as everyone has pointed out, you really do NOT want. Do not want green. Stay in the blue range.

 

Richard,

Accelerate briskly? Seriously? I'm still learning, I haven't even had this car 3 weeks. I've been babying the accelerator when at a stop (when nobody is behind me) thinking that will achieve the best mileage. Hmm, seems counterintuitive but as I said, I'm new at this game.
One other question: why do the arrows go back and forth constantly from charging to electric motor usage when I'm traveling down the highway with the ICE running on a flat stretch? A buddy of mine states thats normal but it sure doesn't look it as it's going back and forth on the screen. What's going on here?

Thanks