Scanguage questions

according to Toyota Prius - Wikipedia, the free encyclopedia

The engine is 1.5L

dont use this code:
TXD: 0033
RXF: 0100823B0000
RXD: 140C
MTH: 0001000A0000

Theres a problem with the scangauge's inability to handle 12 bit signed integer values... so it doesn't display negative values correctly.

I believe this code should work:

TXD: 07E321CE
RXF: 056186CE0000
RXD: 3810
MTH: 0001000AF333

 

Thanks Danny for pointing out this discrepancy. I was using the 2nd set of values (from the Scangauge web site) and I never got a BTA reading. I have changed to the first set of values and now it works. I get a positive value when the battery is supplying current and a negative value when the battery is being charged.

 

Re: Fix for 12bit problem

If the scan guage can't cope with a 12 bit signed value then you should be able to read four bits past the data you want, (ie for a total of 16bits), and then divide the resulting number by 8, which will shift it 4 bytes to the right, tossing out the garbage you orriginally recorded and leaving you with a correct padded 16 bit signed value.

So, if the problem code is:
TXD: 0033
RXF: 0100823B0000
RXD: 140C
MTH: 0001000A0000
(12 bits divided by ten)

Then
TXD: 0033
RXF: 0100823B0000
RXD: 1410
MTH: 000100500000
(16bits results in a number 8 times bigger, divided by 80)

Should produce the correct result with +- sign and everything.

I have a Highlander Hybrid, and have yet to get any SOC/Amp/Volt reading yet, i think there must be subtle differences from the prius system, and of coure can't try this out to let you know if what i have said in theory hold true in practice.

 

Re: Correction

Sorry, my bad, to shift four bits to the left you must divide by 16, (not 8).
So use:

TXD: 0033
RXF: 0100823B0000
RXD: 1410
MTH: 000100A000000
(16bits results in a number 16 times bigger, divided by 160)

 

Gosh my math skills must be horrible... I should have tried that.

 

Ok,

Danny or anyone,

I am about to place an order for the ScanGaugeII w/ the add a gauge included and one of the deciding points was the HV battery current (in and out). It looks like you have the code figured out.

Can anyone verify?

Another point is that I'm not sure that I'll realize that much benefit, increased mpg, by installing a ScanGaugeII. I'm pounding out 63mpg tanks lately with improved driving skills over mainly highway commutes of 35 miles each way. Any thoughts?

Kaos1

 

I have operated a newly purchased ScanGaugeII with XGauge since this afternooon. As of today the Prius "Battery Current" code posted on the Linear Logic web site is still wrong. However a simple Google guided me to correction posts with these values (differing in a single character form official one), which worked apparently correctly:

TXD: 07E321CE
RXF: 056186CE000
RXD: 3810
MTH: 0001000AF333

Using these values, regeneration, engine charging, and regenerative braking all give negative values, with maximum regenerative braking appearing to be limited to just slightly over 75 Amperes. I've not yet done a full effort acceleration, but with just a little vigor from a dead stop I've seen 110 Amperes max sample value propulsion current.

I prefer the Fast (1 second) update rate.

I've so far used the ScanGaugeII for about half an hour each on a 2006 Prius and a 2002 Audi A4 1.8T. I like it very, very much. It is so interesting it is bound to cause crashes by distraction. Seriously, so far this is its worst flaw.

 

I can't decide if I should buy a scan gauge. What are the benefits of having one in the prius?

 

The ability to alleviate your curiosity of what the %!@% is happening and why at any given time... limited only by the available gauges on the scangauge.

If your the self-improvement type, you may also increase a subtle mileage improvement as you hone your driving technique.

 

I'd hesitate to claim you'll get your money back--$159 is a lot of gasoline savings.

Still, I'm very glad I bought mine. I'll call it SG2 here.

Possible Prius benefits:
1. if you get a check engine light, you'll be able to read the code out, which might help you make a more appropriate response. It would comfort me to know better what is happening.
2. on the Prius, you get almost ten times the resolution on battery state of charge from the SG2 as from the display on the car (it reads in half-percent increments, and you'll eventualy see it range from something like 40 to something like 80).
3. on the Prius you can learn a lot about "what it is really doing" by watching the current in and out of the traction battery.
a. by coasting on a very slight uphill down from 15 mph to 5 mph I learned that the transition from "simulated engine drag" at higher speeds to "simulated automatic transmission creep" at very low speeds goes through zero at just about 10 mph, but is a very gradual transition on both sides of 10 mph.
b. by watching the current meter as I descended a several mile gradual hill (about 4% grade, I think) at 50 mph, I was able to watch the current and confirm that cruise control can use both drag and propulsion over a fair range--I think I saw amost +/- 20 amperes--to maintain speed at 52 mph. This confirmed my long suspicion that using cruise controls going down our long Albuquerque hills works better than I'd have dared hope.
c. by watching the current meter, I learned that regenerative braking seems to be limited to about 75 amperes--above that you are burning brake pads and losing the benefit of incremental energy recovery. On this last point, SG2 can help train me. I'll watch the meter for a while during braking, and train myself on how 65 Ampere braking feels. That should help economy. I already try to plan ahead enough to avoid most braking, of course, but when it becomes inevitable, shaping it to stay in regeneration where safe and feasible should help--and the car displays are no help at all in doing that.
d. It is just fun to watch things like coolant temperature, inlet air temperature, ignition spark advance angle, and so on. I'd have to score this one as "play value" rather than likely to save you money or operate your car better.
e. the mpg meter is not limited to 100 mpg as is the one on the car. In some low-usage cases, it is still useful to see variation above that. While not a Prius example, I'll mention that going down a 4.5 % grade hill in neutral in my Audi at 52 mph, I watched my mpg drop from about 260 to about 165 when I turned my air conditioning on. From the horsepower display I learned that the engine had to supply about 2.5 extra horsepower to operate the A/C compressor.

 

What do you mean by limited to 75 amps? I just coaded my scangauge for hybrid battery amperage over the weekend. On my drive in to work this morning, coming into a stop at the bottom of a steep hill, I saw a reading of about -90 amps. I have seen other references on here to 60 amp regenerative breaking as the most efficient. However, I just did a search and couldn't find a source for that information. Is it ancedotal only or does someone have data to support this. If I'm seeing -90 amps does that mean that the friction brakes area also being used? Is there some limit where it switches from regenerative to friction breaking? Or do the two systems work in concert? One thing I haven't done yet, but I considered trying, would be to stomp on the brakes for a true emergency braking situation and see if there is any regeration.

Also, I have a question on the HP readings. Just fooling around to see how high I could get, I got upwards of 500 HP (I think around 5000 RPM). Obviously the Prius doesn't have a 500 HP engine. So I'm wondering how this works. As I recall the stated HP for an engine is at a certain rpm, but I don't remember what that is. I know that torque also comes into play here, but I can't remeber how that fits into the picture. One further question, I've noted that while using electric only (ICE off), the HP reading is zero. Shouldn't there be some reading for the horsepower that is being generated by the electric motor?

 

I mean that as I pressed harder on a downhill stop from appreciable speed that harder pressure seemed to stop giving more negative amperage about 75 A. I have almost no doubt there is a limit, but it may be speed dependent among other things (temperature?, state-of-charge?), and it may well not be 75 A. Somewhere I saw a Toyota technical document regarding the pre-2004 model which specifically alluded to a limit, somewhere near 60 A if I recall correctly. As the current model both has a higher-power motor and is generally claimed to reclaim more brake energy, I assume this number is higher for our model.

SG2 does not know how to display horsepower as shipped with the current firmware, you put it in as a customer-inserted parameter. If you see a display of 500 for HPR, I think either you inserted the coding incorrectly and are actually looking at something else, or that your Prius is defective in a way that puts invalid horsepower data on the CAN bus for the SG2 to read. I've certainly not seen that on my Prius. On my Audi A4 1.8T, which is stated to have a maximum horsepower of 170 at 5900 rpm, I've yet to see values over 130, though I've not taken it to a long uphill and floored it in a gear that will reach 5900 rpm yet, and expect to see appreciably more. I've spent less time watching the HPR reading while running the Prius, but am very sure I've not seen it over 100.

It is true they spec maximum horsepower at an rpm, but that is generally the rpm for which the engine can develop the most horsepower, which for most auto engines is quite close to the maximum rpm permitted.

 

Thanks for the quick reply!

Do you mean that -75 A is as low as you have seen it go? I guess what I'm wondering is if I'm seeing a reading like -90 A does that mean that I'm using the friction brake or would the current reading drop back to near zero in that situation.

Hmm? That was way higher than I expected, but figured I was just misunderstanding how horespower is rated. I coded it in using the following XGauge information.


TXD 00
RXF 400080000000
RXD 0000
MTH 000A00170000
NAM HPR

I suppose I could have made a mistake though. I'll have to try re-entering it, just to be sure. The reading does seem to rise and fall as you would expect with acceleration (other than in electric only as I mentioned above).

 

No, or not just that. The value gets gradually more negative as I brake harder, but stops getting more negative about there. That apparent saturation is the way I'd expect a limit to behave.

I'm sure you won't get a "credit" in the traction battery current display for friction brake use. I expect that with the onset of friction braking at speeds higher than very low the regenerative current will remain, and not drop back toward zero until your speeds get down too low for the motor system to be able to deliver full braking. I've seen a sketch diagram of that last effect from a Toyota source. It was conceptual rather than quantitative, but seemed to suggest such a speed was quite low, possibly below 10 mph.

The coding you post for HPR is the same one I read from the printout I used to code in my own. One of us got it wrong, or our cars differ, I think. Within a day or two I shall undertake a long uphill and floor it long enough to get a near maximum reading and report. It would be good if you would mention a set of conditions which lets you get multiple consecutive readouts above 150 horsepower. I'm confident the gasoline engine in this car does not actually do that.

 

The display for HP seems to be 10 times the actual value - if you divide the display by 10 you get reasonable numbers. i.e. it should have a decimal point before the last digit.

kevin

 

A factor of 10 doesn't seem to work for me though. As I mentioned, I was really stomping on it to get up to a reading just over 500 HP at around 5000 RPM I believe. I would expect the engine would be generating more than 50 HP in that situation, but obviously much less than 500. Maybe around 100 HP would make sense. But that would mean it's off by a factor of 5, which seems strange.

 

While that might be a reasonable guess for what is going on in the case of ImPriused, it does not describe what I see.

1. On my Audi, for horsepower under 100 I see a decimal point and tenths. It shifts format past 100, and just displays three digits.

2. On my Prius, I just see nn.n (i.e. a properly formatted display to a resolution of tenths of a horsepower) all the time. The maximum I've extracted today while trying was 67.2 horsepower at about 4992 rpm, with full throttle on a 4 % upgrade but limited by a 55 mph speed limit. I was not at maximum for more than one or two sample points, and doubt this is the most that could be found, but suspect the 76 horsepower "in the book" is not going to get displayed, at least at this altitude and temperature (about 5800 feet, about 85F).

So, ImPriused, we are are back to saying something differs between your Prius/SG2 and mine.

My Prius is a 2006 model. My SG2 is running version 3.15 firmware. The release notes say that the 3.15 version was required to fix Prius compatibility problems in 3.14.

Regarding regenerative braking, I was wrong in suggesting a -75A maximum. Today I saw a little more negative than 90 more than once, and did not have a good opportunity to probe for the limit. It was surprisingly easy to get to -90A.

 

I'm seeing 3 digits for HP, with a decimal point when below 100. Maybe it is off by a factor of 10, given what Danny is saying (which I agree with). It appears the SG is only giving the ICE HP and not that of the electric motors.

I have a 2007 Prius. Not sure on the SG2 firmware version. I ordered it in Nov '07. Is there a way to get it to tell you what version it's running? Maybe I did get the 3.14 version that has compatibility issues with the Prius. I will look into this.

I'm glad you were able to get -90 A breaking. I'm assuming that much breaking should be avoided if possible to ensure that the friction breaks aren't being engaged.