Scangauge 3, impressive customer service, and potential energy pulse-and-glide

Story #1: Unbelievable customer service from Scangauge/Linear Logic

I bought a Scangauge 3, which I absolutely love.

The sole drawback, so far, is that it doesn't allow alarms ("monitors") using negative numbers. As a result, I can set it to chirp out a little reminder when acceleration draws more than 75 amps, say. But I could not do the same for regenerative braking current, because regeneration shows up as negative numbers.

I wrote them an email last Friday, explaining the issue. They rewrote the firmware and gave me the link to new version, so I could be a beta tester. Downloaded it Tuesday, tested it Wednesday. Works perfectly. The car now gives a little chirp when braking current exceeds 75 amps. (That is, when it is more negative than -75 amps).

I know some of the PriusChat founding fathers were in pretty tight with Linear Logic (the maker). I imagine when those folks talk, Linear Logic listens.

But I find it astonishing that when some nobody emailed them with a complaint, they turned around a fix in two working days.

Anyway, problem solved. When they release the updated firmware, you'll be able to set alarms for gauges that that show negative values.

2) Potential energy pulse-and-glide, helped by the Scangauge.

Pulse-and-glide is always incorrectly described as alternatively speeding up and then coasting, as a way to reduce gas consumption. Load the gas engine optimally, store excess output in the form of speed (kinetic energy), then turn the engine off and use up that stored energy (coast). It improves mileage because, done right, it only used the gas engine at its most-efficient loading.

With a Prius, you have the added bonus of being able to use the battery and motors to extend the glide portion of the pulse-and-glide. But any car can do pulse-and-glide.

My point is, that's *a* way to do it, but it's not *the* way to do it.

Here in the rolling hills of the Virginia Piedmont, the obvious alternative to storing energy as kinetic energy (speed) is to store it as potential energy (height).



Gas up the hill, briefly let off the accelerator, which then shuts off the gas engine until the next uphill. You proceed at roughly constant speed, but varying potential energy.

Back when I drove a Gen 2 Prius (2005), I could only get improved gas mileage on very specific terrain. Just a couple of roads in my area had the right shape-and-spacing of hill to allow the relatively weak electrical side of that car to keep up speed, as needed, in the "coast" phase.

With the Prius Prime, I find that "potential energy pulse-and-glide" is a lot more widely applicable, owing to the enhanced EV capability of the car.



So, today, my wife and I took a little drive out to the Snickersville Turnpike and back. That's a Scenic Byway in our area.

No interstate-type driving, just 55 MPH arterial roads, then country lanes, and small-town streets. All done in HV mode. We got slightly over 82 MPG for the trip,above. (That's a slight cheat, as battery SOC fell from 64% to 61%. But "excellent gas mileage" is definitely the gist of it.)

Traditional pulse-and-glide gets a bad rap for the obvious reason that repeatedly speeding up and slowing down in traffic is an obnoxious and dangerous thing to do.

But in rolling terrain, at moderate speeds (below 65 MPH, say), in a Prime, you can do pulse-and-glide by "playing" the hills, at constant speed. Briefly let off the gas pedal as you near the top of a hill, baby it on the downhill to stay in EV mode until the next uphill segment.

The Scanguage 3 is helpful for this, because the battery current readout, with ICE off, lets you know how many horsepower it takes to keep the car moving forward. Once that current gets above 40 amps or so, you're edging up toward (40 amps x 350 volts / 750 watts per HP = ) ~20 HP. At that point, I figure that if I depress the gas pedal to start the ICE, I ought to be loading the ICE in the 30-40 HP range, which should be enough load so that it runs near peak efficiency.

The instantaneous MPG gauge also lets you know, for sure, when the ICE is on and when it is off, which is sometimes useful.

The upshot is that I glance at the battery amp gauge to determine when to terminate the EV "glide" portion of the pulse-and-glide. Rather than just guess at it.

On a drive like this, I'd likely have gotten 65 MPG in any case. The difference between that and 82 isn't going to save the planet.

But for me, it's fun. It's like playing a video game. Instead of driving a boring 55 MPH urban road, I'm working the car to see if I can beat my previous high score. And I think I'm beating my prior high scores in the Prius because I now have a tool to let me monitor the absolute level of energy consumption on a real-time basis.