Battery use at or near hwy speeds question

What was the outside temperature? The fan is programmed to speed up as the car goes faster, since the noise from the car will cover the noise from the fan (usually). The battery is used a little at higher speeds, but only hills really work it.

I doubt going 100MPH killed the HV battery. I may or may not have taken my Prius to 90MPH a few times and its fine.

 

Why do you minimize battery use?

 

Minimizing conversion losses is a good plan. How sure are you that your Prius is not charging the battery?

 

Your driving style ensures that the HV battery will be near optimum charge (60%). At this level the car is programmed to make full use of the battery to minimise fuel consumption. You can't win!

GT-I9300 ?

 

What you are really going for is to minimize the total energy use and that includes the battery.
Mostly because the bulk of the energy stored in the battery comes from the gas engine too.

I consider this to be a "hyper-milling" technique but some of the components are pretty easy habits to cultivate with just a little practice.

 

The battery is used at highway speeds to help maintain speed. If the car didn't use the battery it would have to use the engine, requiring fuel enrichment as it opened the throttle. This is a major inefficiency of gasoline powered engines.

I'm talking here of almost imperceptible uphill spots as you drive along. If you watch the schematic display showing the flow of energy you can see this at work. Best seen when using cruise control.

This use of the battery is not problematic. Taking the battery to full charge or low charge levels is what will damage it. That's why the Prius operates the battery between the 30% to 80% charge level. But you -can- shorten the batteries life by deliberately taking the charge level to high levels or down to low levels. I doubt you could actually -measure- the shortened life however. As I'm sure you have seen, the systems won't let you get into "dangerous" areas for the battery.

 

The increased fan noise doesn't sound good. Have you ever checked if it's clean? Apart from the fan noise increase, is the battery behaving normally, ie: charging/discharging readily?

 

I used to be at the opposite of you. I tried to use battery as much as possible and hope to recover the electricity from mandatory acceleration/higher speed battery charging/generative braking. I stopped this practice since i was aware of the problem of traction battery wear.

Use the battery as much as possible actually gave me quite high MPG. I once got 60 mpg on a 15 miles trip that consists of half highway and half local.

 

I personally do not see the point of saving the battery, the whole idea of hybrid's is the efficient use of all excess energy. This is done by both regenerative braking and storing excess energy from the engine in certain circumstances when the engine has to run faster. Then the energy is put to use as needed to boos performance like climbing a hill, ect...
All you have to do is watch the energy flow display to get a good idea of how this actually works. Plus if you do some research you will find that Prius battery failure rate is extremely low. I believe I read somewhere that for all Prius-es ever built it is around 0.3 of 1%. Use the battery, is my take, as the is what it is there for in the first place.

 

So here we have the same "old" problem being quoted again.

On short trips, the displayed MPG figure more closely resembles an "instantaneous" number than a true average. Under many conditions that use a lot of battery, the system seems to "estimate" that those conditions will continue to exist......seemingly forever. And if the car doesn't estimate that, then the driver DOES.

I routinely see numbers in the low 60's in my C with mixed driving on trips of 20 miles or less.
But then when it's time to fill the tank and get the "real" mileage, it usually ends up in the low 50's.
And the actual is always 3-4 MPG lower than the computer says on the trip ODO.

 

That is absolutely correct.......for most owners who are not obsessed with squeezing out the last drop of mileage.

I think you are missing the main point, however.
It is not really "saving" the battery by not using it; that is just a side effect of using as little TOTAL energy as possible, since most of the battery energy really comes from burning gas too.

 

Great point.
In fact, even if I use the battery as much as possible, I have never seen one occasion that the battery indicator goes down to less than 2 bars and then the ICE fires up to charge it.

It is possibly because I don't really stay on the all EV range all the time... I don't drive in local speed too often. From acceleration to catch up traffic to other scenarios, the battery mostly keeps at 3 to 5 bars...

I don't practice this way any more tho.

 

When you get down to 2 bars of battery then the display turns purple. Shortly after hitting the 2 bar level the ICE will turn on to charge the battery and will not turn off until the SOC is above a certain minimum threshold.