Scangauge Newbie - Suggested Gauges

I think it depends what you are interested in ..

For me, first and foremost, the radiator water temp to reassure myself that my grill blocking is not causing problems. Then RPM and manifold pressure for my fuel economy games. I would like to know throttle opening, but do not know a direct gauge or a surrogate other than MAP. Lastly I like knowing the traction battery amp flows, because I am curious how much energy is required to freewheel the ICE, and to follow regen.

For some reason manifold pressure (MAP) does not work -- yet ;-)
I have this readout set to Ig timing for now
Battery current flow is an x-gauge
Radiator temp is fwt (farenheight) or cwt
RPM is ... rpm

 

I use RPM (to monitor exactly -what- the HSD is doing).
12 volt battery voltage as I was worried it might be damaged (it probably won't be)
coolant temp to monitor my grill blocking and the car's warmup (or lack thereof in winter)
and fuel consumption rate because it was the only other non-xgauge I considered useful.

 

I use:

RPM (ICE revolutions per minute) - you can tell if ICE is running, off or spinning without fuel (in Warp Stealth - it spins at approx 960 rpm)

°cWT (Coolant Temp) - you can tell if engine is warm and also what "stage" of the 5 stages the hybrid system is in.

IGN (Ignition Timing) - you can tell if you are in SHM (super highway mode - look it up - IGN will be +13 or 14) you can also can tell when the engine is off ( it "parks" at +5 degrees)

GPH (Gallons per hour) - this is somewhat redundant to using the Prius built in consumption screen, but I like it because I can tell when the fuel is cutoff vs just at a low rate. Also, I can tell when the car is about to drop out of SHM to Warp stealth by watching GPM (it will drop out at ~ .34 gph). If you divide instantaneous speed by instantaneous GPH you get instantaneous MPG. Example: If you are traveling 50 mph and GPH is 0.5, then iMPG is 100 mpg.

 

I find IGN useless. I think amps (current) helps a lot more, as it prevents you from feathering the pedel too much and letting it charge the battery instead of driving the wheels. It also allows you to aim for that 60amp braking.

 

I disagree. In the same way that we learn when to start coasting based on experience how quickly the car slows down, if we know what the slow-down rate is during most efficient regen, we can use it the same way. Not all the time of course, just when it is safe and appropriate.

 

I display:
coolant temp (because I grill block)
rpm and ign so I can get to shm easily
current to hv battery, for braking and gliding

 

I see your point. But there are times where this amp scangauge xgauge can be useful too. It lets your know how much power your using when when in "EV" mode. Once you know that, you can determine how much more power you use before triggering ICE ignition. You can also use this gauge to avoid using the battery when the car is doing its warmup sequence - where it idles with a negative ignition timing and doesn't produce enough power.

I would have to point out that the prius not being in neutral drains about 5+ amps when gliding at 40mph (depending on what speed your going, it drains less if your traveling at a lower speed). If shifted into neutral, it drains about 1 amp. What I do is shift into neutral and save as much energy as possible, then try to brake enough (after shifting to D) to prevent going above 40mph until reaching my brake point, at which I try to stay at or under 60amps at all times.

I'm not sure if the energy saved while coasting in N is better then a more gradual deceleration by using regen all the way down the hill, but I think we can both agree that going above 60amps is bad for efficiency - especially when planning your braking on the highway... You see a pileup a few miles down - or your exit is coming up very soon, you'd know when to start regeneration as opposed to just slamming on the brakes 50 feet from the turn.

 

I display RPM, coolant temp, MPG, & GPH (sometimes voltage). The unit sits on a beanbag mount in the corner.

 

IGN - top left, TPS - top right. Used to determine if you're in Super Highway Mode, S1 (IGN 10), in a glide (engine off, IGN 5), etc. If you can keep the IGN at 13-14 and the TPS at 16-19 it equates to anywhere between 60's-80's MPG depending on the slope of the road. Speeds run anywhere between 42 and up to maybe high 50's. Great for secondary roads where the posted limit is between 45-55 MPH.

RPM - bottom left. Used to follow hobbit's advice on most fuel efficient ranges of the HSD. I only really glance at this, mostly when trying to find the balance between speed, and efficiency when pulling up a hill (trying to keep it no more than 2k RPMs).

gps - bottom right. Gas pedal sensor xGuage. It is not offered as a built-in, and must be added. There's a list of known good guages over at cleanmpg.com. Maybe here as well? I've never looked. When in a glide, keeping this under 10 (maybe slightly more) keeps from using energy from the battery to move the car. Regen seems to be from 0-1.5 on my car. IGN 13-14, TPS 16-19, and gps 16-19 (when warmed up) are about as efficient as you can get in the 42-50's MPH range without resorting to a pulse and glide routine. You can also use gps to try and hold Warp Stealth (IGN 5, RPM in the 900-1000k range). Basically, at highway speeds on any kind of downhill, let off the pedal completely to cause the engine to go into fuel cut, then back on the go pedal. If you stay out being too deep on the pedal (keeping it under 10 or so) gives you a free wheeling event. You'll pull some energy off the pack, and slowly lose speed. Unless the slope is fairly pronounced. You can pickup speed, maintain speed on steeper hills. This returns 99 MPG on the Prius instantaneous display for as long as you care to hold it.

I guess it all depends on how hard you want to "work" (and it can be work) at keeping within the highest mileage range the car has to offer.