A question for those who have a ScanGauge II...

When I was using SG, I still used the vehicle guess gauge. I didn't trust the variation in the bladder to cooperate with SG's calculation. Bottom line: When the last pip starts flashing, I fill up at the next opportunity. Or if I'm on the road in unfamiliar territory (e.g., the drive to Hybridfest), I start looking to fill up when it drops from two pips to one.

 

<div class='quotetop'>QUOTE(Green Hokie @ Jul 25 2007, 09:23 PM) [snapback]485147[/snapback]</div>

You need to calibrate the readings (distance, fuel usage, tank size, etc) of the SG. This takes the first two (2) fill-ups. First time to fill up the tank to an easily repeatable level and "zeroing out" the fuel used. Second time, refill (preferrably from same pump/nozzle) to the same level and adjust calibration factor to the correct number of gallons/liters used.

After that, it's pretty accurate. You will need to remember to reset the Tank Fill-up every time you refuel. (An EASY thing do do, but DIFFICULT to remember to do since fill-ups are so infrequent). B)

As previously stated, you will need to adjust/calibrate the miles/km traveled to ensure the SG calculates the mpg and distance to empty correctly.

 

OK, I spent TOO MUCH TIME perfecting my post, while others got right to the point and beat me to the punch, but I wanted to add, I have had some trouble calibrating the Fillup Feul Used. First tank, I adjust it down a little to - 3 %. Then each successive tank I over correct +5% -4%, +2%. -8%, and it becomes never ending.

I could start again at zero, but I had the idea that instead, I could compare my daily MPG averages between Scan Gauge and Prius computer for a few days, take the average percentage difference, and then use that percentage to adjust at gallons at fill up. Does this make sense?

Also, to compensate for the bladder inconsistancies, I think it would be best to enter a conservative tank size such as 9 gallons rather than the full 11.5 or whatever Toyota specks call for. Bottom line, I think the scan guage could be a more accurate tool than Guess Guage, but not for the purpose of tyring to get down to the last gallon of feul before filling up.

<div class='quotetop'>QUOTE(Green Hokie @ Jul 25 2007, 06:23 PM) [snapback]485147[/snapback]</div>

The Scan Gauge II could be more accurate than the Guess Guage, if you understand its proper use and limitations:

1. The Scan Guage does not receive feul tank level information from your car, but feul used signals. Scan Gauge depends on you setting it up with some information about your car, including the Feul Tank size in gallons, you must completely fill your tank when you buy gas, and you must tell the Scan Gauge by indicating "Fillup" each time you fill your tank.

2. The Feul to Empty and Miles to Empty calculations are based on the average MPG for that particular tank of gas, so if you are doing the same mix of driving conditions and styles, it can be a great indicator. If you diver the first half of the tank on flat roads with the best of conditions, P & G and slow start in all EV mode, and then on the second half of the tank, you are climbing mountains and drag racing, the tank will run out erlier than the Scan Gauge calculates.

Here is a blurb from manual, and the whole manual.
The TANK selection can tell you much about the current tank of fuel.
For instance, the following display tells you that if your mileage remains
the same as it has since the last fill-up, you will run out of fuel in 92.7
Miles.
< 92.7 MILES >
<TANK TO EMPTY
In order for the TANK information to be useful, you must set the size of
the fuel tank using MORE>SETUP>FUEL>TANK SIZE. When
you fill-up, you must use HOME>MORE>FILLUP>DONE to
indicate the vehicle tank has been refilled. It is also necessary to fill the
tank to make the TO EMPTY information correct.

[attachmentid=10131]

 

<div class='quotetop'>QUOTE(koa @ Jul 25 2007, 08.29PM) [snapback]485318[/snapback]</div>

koa,
Yes, what I said IS acurate. Let me elaborate. I agree that the miles till empty will begin to decline rapidly when you use a style of driving that is less feul efficient. This is exactly why my statement IS acurate that the Miles till empty at the 1/2 tank level is inaccurate. The fact that it begins to decline rapidly when you are less feul efficient is exactly what makes the miles till empty readings inaccurate.

Example: First half of the tank, you are getting 50 MPG and you use half of your useable 10 gallon tank in 250 miles. The distance to empty reads 250 miles, assuming you will get 50 MPG for the rest of the tank. You then see a sine that reads "next gas 180 miles" but your Scan Gauge says 250 miles to empty and you go merrily on your way, but the terrane changes to gravel roads over steep mountains and your tires are spinning out now and then. You begin gettin 35 MPG. Yes, the Miles till empty does start to decline faster so that after you have driven only 70 milse, it has gone from 250 miles till empty to 150 miles to empty. These same roads continue for 105 more miles, and then the last five miles is a nice flat four lane road with a 40 MPH speed limit, but as you turn on to this beautiful road, you notice that the Miles till empty is now reading 0, only 175 miles after it was reading 250. You pray for five miles as you coast in on fumes, then a couple of blocks before the gas station, your ICE cuts out and it swithes to EV mode, but you haven't built up your green bars enough, and you turn the last corner, 1 block before the gas station and you see a replica of Lombard St. in San Francisoc, leading up to the gas station. Half way up, and you cannot go any further. Now who will help you push it up to the top of this hill? OK, I will help push, if you will concede that my statement was accurate.

 

NoMoShocks,
I do see what you're saying and agree with it, but the Scangauge will be accurately reading close to zero miles till empty when you help me push the car to the gas station. At any point you fill the tank the Scangauge will be fairly accurate in its gallons to empty and it's miles till empty readouts. If you kept an eye on the miles till empty reading you would probably see a sharp drop 10 miles into you uphill drive to give you an indication you would not make the gas station and could turn around and get gas.

 

I set the tank capacity to 10 gallons on the Scangage. I feel that it gives me at least a 50-100 mile cushion to actual "walking home" empty. In actual practice, even with 1 flashing pip I only got in 8.5 gal. or so. When I check the FILLUP screen after filling, it is usually within .2-.3 gallons when I let the pump click off automatically, i.e., not cram in more gas after the pump stops. I usually use the same 1 or 2 stations for almost all of my gas.

 

<div class='quotetop'>QUOTE(koa @ Jul 26 2007, 11:08 AM) [snapback]485572[/snapback]</div>

Well, I think we are both on the same page. The extreme example I gave is unlikely to happen in real life, but it was just to illustrate that people should not rely blindly on miles to empty. Even on the integrated computers that come on the cars, I have seen it go from 50 to 30 in less than 20 miles, but as long as your goal it to refeul when it says 30 rather than when it says 2, it will likely never be a problem.

There is also still some wiggle room, even with the integreated systems, I have driven 2 or 3 miles on 0 miles till empty. For the Scan Gauge 2, it should never be a problem as long as you enter a conservative tank size like 10 gallons. I mostly wanted people to understand the concept of the Miles til Empty being an estimate.

 

<div class='quotetop'>QUOTE(Green Hokie @ Jul 26 2007, 09:51 AM) [snapback]485503[/snapback]</div>

I am fairly confident that my newly devised method of calibrating the Scan Guage will be much quicker and more accurate. Instead of comparing the Scan Gauge gallons used to gallons on pump at fillup and applying that correction factor, I plan to compare the Average Tank MPG between the Prius Computer and the Scan Gauge, and enter that percentage as the correction factor in the fillup gallons. This will not be dependant of differing top off levels, and should settle in very quickly. I just need to remember they are inversly proportional, that is to say, + 5% MPG on Prius = - 5% gallons used on scan gauge at fillup.

 

Heres an idea:

Run out of gas. (be sure to have a [large] gas tank nearby!)
record the amount of gas you put in the car as the max tank size.
indicate fillup on sg?

then each time you fillup, change the tank size to the amount that you just filled up with. Thus, in theory, you will NEVER run out of gas again.