Scanguage questions

Agree that it is the ICE horsepower.

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As speed drops, the power required to provide a given deceleration rate drops also. I think I got fooled by this, as the amount harder I was pressing on the brake pedal when I thought I'd found a maximum was probably just keeping up with what otherwise would have been a drop. I need to do this test at Interstate speed on a downgrade, so that there is time for the reading to stabilize. At 70 mph on a downgrade, 90 A won't provide a very substantial deceleration rate at all, so there will be plenty of time.

If you try this, you may want to make sure you have the display update rate set to "fast". My SG2 does not seem to remember this setting. For average mpg, water temperature, and such it does not matter much, but for engine parameters faster seems better to me.

 

Thanks. I do have version 3.15.

Turns out I made a data entry error in coding the XGauge for HPR.

For RXF
I used: 400008000000
The correct code is: 400080000000

Oops! Anyone else seeing strange HP readings should double check the code. It may have been listed incorrectly somewhere. I haven't driven it yet to confirm, but the HPR reading with the ICE off changed from "0" to "0.0", so that's a good sign.

 

I did some intentional testing today.

But first let me "incorporate by reference" this extensive discussion of B mode and regenerative braking in the Prius. It has a great deal of detail, some of which contradicted things I'd guessed about how the car worked. Some of today's tests were checks on those contradictions, and the things I've checked support this page's points.

The big error I had was that very early in our ownership I got the impression that B mode was purely compressive braking, that you got no regeneration as part of its drag, and that if you used the foot brake you'd get none of the additional deceleration from regeneration. Wrong on all counts. My test condition was about 50 mph on about a 4% downgrade. Coasting in D, I got about 21 Amperes of regeneration. Switching to B, I got about 30 Amperes. Gently applying the brakes, I got up to about 90 Amperes. At this time the engine water temperature was about 170F, the battery state was about 5 bars, and the battery was probably still pretty cool. So Regen current may have been limited below maximum by low battery temperature.

On the peak horsepower topic, I used the return trip up the same grade first to run down the state of charge. I saw one bar on the display and something like 35% on the SG2 readout. Flooring it gave not so much acceleration, so I was able to keep it floored for a decent number of readouts. The reported horsepower varied slightly in the 64 to 66 range (probably the 5800 foot altitude and 90F ambient temp held that down from what you lowlanders can see).

On the "interesting behavior of the Prius control logic" topic, I was fascinated to see that a second trip up the same grade about ten minutes later at the same speed (50 mph) showed utterly different battery charging behavior. I started the climb the first time at 8-green 75% State of Charge, and it dropped the whole way up, getting down to 1 purple 33%. The second trip up the hill obviously started with a considerably warmer battery (on my second trip down the battery fan kicked on near the bottom of the hill, so I drove a few minutes on the flat during which it shut down). At the hill bottom I was about 55% SOC, which quickly dropped to about 50 in the initial uphill acceleration. But the steady climbing portion found an operating condition of slightly charging the battery this time, so it was 52 or 53 by the point at which it had dropped to 33 on the first trip!

The elves of Toyota obviously take more things into account than are easily controlled in an experiment.

I never did see the 100A regen peak mentioned in the linked page, but it seems likely that the peak is lower than maximum for battery temperature either too hot or too cold. I may have hit both sides of the sweet spot.

My other attempted measurement was air conditioner compressor and fan power consumption. My idea was to put it in a condition of fixed current draw, then note the change in traction battery current when turning on and off the air con. The awkward thing is that I got two answers--very roughly one was about 3 Amperes, and the other about 7. Possibly I fouled up, or possibly this air con can operate at more than one compressor level.

 

Good stuff archae. Thanks for the information.

I have done a little "testing" myself with AC on and off while in P with the ICE off and all other accessories off. I've seen a range of about 2 to 8 amps above a general current draw of about 1 to 2 amps. So very similar to your data.

 

ScanGauge II occasionally shows a minus sign after RPM, e.g. "1180RPM-". Not when I'm moving backwards either Is this just a display bug or does it mean something?

 

Actually that minus sign is for the next parameter over to the right.

I agree that it is easy to mistake this, so I generally try to put parameters capable of displaying minus signs in the left side.

It would be even nicer if the SG2 could figure out how to place the minus sign just once character to the left of the most significant displayed digit, but it seems to use the left-most available character instead.

 

I am interested in monitoring MG1. Which parameters of MG1 can be monitored with a scanguage?

 

None have been discovered so far.