Got a prius, should be interesting to mess with....

[Phase]

Prius is so different. That “ pulse and glide” hybrid system or going from engine to ev and back to engine and then back to full ev is how my Ioniq drives all the time no matter what. That’s why doing scanguage or mpg tests are so hard in it. Even on the interstate, the Ioniq will charge the battery using the engine and propel the car for about a minute, then it’ll switch over to full EV mode for about 30 seconds to a minute, then back to engine and so on. Even at 80-90 miles per hour

[ps2fixer]

I suspect you have a 2010+, my 2006 can't do EV mode above around 41mph, it has to keep the engine running at the higher speeds. There's battery assist when there's extra battery charge to burn, but in mine it targets around 60% state of charge, down hills it regens a little, and up hills it uses some battery charge.

I have a scan gauge now, so I'm able to check the hybrid battery state of charge, so if the battery at start and stop is the same, the tests should be reasonably valid. Longer tests would tighten up the accuracy. Knowing how accurate a test is can be hard to figure, like if gains are seen, are they just in the margin of error, or is it for sure at least a small gain.

With the engine running, it's hard to get the pedal just right to coast when above the EV threshold speed.

I think I might have figured out another oddity with this car. I have a small zig zag in my trip, in the short run I only get up to 35mph before I'm looking to coast. Because I just coasted for the stop sign, that's the section of the trip it seems like it refuses to turn the engine off for while coasting. My guess is there's some sort of timer between engine off events or something like that.

I've also had it a couple times I coasted into a parking lot or my parent's place and the engine was still running but fully warmed up. As soon as I put it in park the engine turns off. I'm pretty sure the EV mod will help in those situations.

Instead of making the pedal try to predict the coast mode, a simpler mod should be possible with a switch with dual contacts and a resister, press and hold (or toggle on) for coast. Kind of like an in car kill switch for P&G.

I noticed that when the battery is charging back up, mpg vs speed seems to be a bit different. I don't remember the exact mpg I was seeing, but it looked like 38mph vs 45mph the 45mph was as good or slightly better mpg while the engine was charging the battery back up. I'd have to put my scope on the battery leads to monitor if it was charging less or try to understand what it's doing differently for different speeds. It would be interesting to try to build a rough chart of speed vs mpg while battery is charging (such as after using EV mode). It seems like it has two modes, below around 54% I think it charges the battery more and above is the typical light charge to slowly get it to around 60%. Should be something interesting to check into at least. I'll have to check my probe specs to make sure the higher voltage won't be a problem. Rear of the car is loosely put together, so shouldn't be hard to get to the hybrid battery leads.

I'm still learning the software for the scope, I know there's a datalogger program too for longer scans. I'm not sure if the points it reads are instantaneous or averages over time.

[hayden55]

Phase has a Hyundai Ioniq. I know it is confusing. The way he was talking I thought he has a Prius as well. Phase you should put your car in your garage so we know where you are coming from.
https://ecomodder.com/forum/emgarage.php

[ps2fixer]

Ahh I see, that makes sense. A few things didn't seem to line up with what my car seems to do.



Anyway, another small update, I did the EV mode button mod. Need to get a button yet, but now that I've looked at the wire diagram and such, I see what the mod was intended to do for the switch side of it. Basically the instructions are to hook the EV mode pin on the computer to the headlight switch where you normally pull black to flash the brights is converted to ev mode (or spliced so it does both).

Electrically speaking, it's a momentary connection to ground, so a normal push button that doesn't latch on would be perfect, there's a couple knock outs on the left side of the steering wheel, so that seems to be the simplest place to install the switch.

For right now, I just have wires ran willy nilly to test out the mode. Looks like it doesn't work as an engine kill switch if you're going 35mph or faster, but being able to turn the engine off at lower speeds is kind of nice when coasting when the car doesn't want to turn it off on it's own for whatever reason.

Also my scan gauge glitched, bunch of the names of sensors have a jumbled up character like MPH turned into something like M@H and the MPG gauge was stuck at 2808. Not sure what's going on, but hopefully once it's been long enough for this "trip" to be cleared out of memory, it will return to normal.

Seems like EV mode limits the discharge to about 45%, I was messing around and took off hard and it ended up dropping down to 39.5%. With the little ev mode messing around I did, i was hoping to see what kind of mpg it would have gotten, I only assume it was worse than normal since it wasn't really being used in ideal situations.

I think the throttle pedal mod would probably give me more effect than the EV mode button, but it's nice to have at least limited control over the engine getting turned off. I'm kind of thinking it would be interesting to do something similar for making the engine stay running and see if I can measure the effectiveness of switching between ev mode and charging the battery vs steady state driving in normal hybrid mode say at 35mph. My guess would be letting the car do the ev mode then recharge would give better overall mpg vs forcing the engine to stay on and avoid using the battery at all. Concept is pretty simple, hvac settings to max heat and leave the windows cracked (same amount for both tests) to keep engine heat demand on. If that doesn't work. maybe there's something else I could do with the wiring.

Oh yea, looks like my wiring has already been messed with some, looks like 4 wires or so have electrical tape wrapped around them that doesn't look factory. Half scared to pull back the tape to see how the splices are made.

Just thought of a potential way to trick the computer into making the engine stay on with no extra load. Pull the 10 amp A/C (HTR) fuse and the inverter for the ac compressor won't have power and the ac water pump looses power too. Clearly would need to be tested, but might be an option. It's not too hard to add a relay + fuse to remotely control the power to the AC system and have the power on a toggle switch. Would be interesting to test with at least.

Looks like the ac controls are done over the canbus, so that might be another option, but no experience in that area yet.

Got word back from the company I ordered the trailer light kit from, I have another week to wait, it ships out around the 17th and I should get it around the 20th. I guess that's around the time I get to install the kit, the hitch, and assemble the back half of the car like it should be.

I still need to swap out the interior lights for LED's as well, first ones I saw back when I thought of that weren't cheap, I don't need anything fancy, just less power draw than stock is what I'm going for to draw the battery down less. Even though the battery doesn't have much capacity, it seems to be doing alright so far. Would prefer to hold off on the battery at least closer to winter time since the correct battery is around $200.

[ps2fixer]

Got my first experience with using AC somewhat heavily in this car. Set it to 75F auto recirculate and wow does it suck a lot more gas. Engine off costing the hybrid battery just drains fast, I'd dare to say the AC takes more energy than making the car move at steady state 20mph on a gravel road slightly up hill lol. The last time I drove the trip with lights on I got like 57mpg on the scan gauge, this time it was more like 48mpg in the day time but with ac on. Coasting was as much or more than before, no EV mode stuff except the last leg to my driveway the engine didn't want to turn off, so put it in EV mode for the last coast.

I haven't tested yet, but I suspect windows down might get better mpg in this car. Other option is to manually set the temp to max cold and manually set air speed to 2-3 bars from what I read in another thread. Kind of amazed how much extra fuel the AC system draws, I don't remember the AC effecting my Corolla too much but it was directly driven off the engine via belt.

[Drifter]

The SAE tested fuel consumption with windows down vs maximum A/C at various speeds using a 2009 Corolla and 2009 Ford Explorer and found windows down was always more efficient in the Ford Explorer and more efficient in the Corolla at speeds below 75 mph.

At steady speeds between 64.4 and 113 kph (40 and 70 mph), both vehicles consumed more fuel with the A/C on at maximum cooling load (compressor at 100% duty cycle) than when driving with the windows down. The Explorer maintained this trend beyond 113 kph (70 mph), while the Corolla fuel consumption with the windows down matched that of running the A/C at 121 kph (75 mph), and exceeded it at 129 kph (80 mph).

https://www.sae.org/publications/tec.../2013-01-0551/


Again that was maximum A/C and these were conventional internal combustion cars with belt-driven A/C compressors so the break-even speed in your Prius should be lower than 75mph especially for moderate A/C usage.

Personally I run windows down until about 45mph. At higher speeds the noise starts to bother me (older cars seem to have much less buffeting & noise with windows down). I'll run windows up with maximum ventilation (A/C off) fairly comfortably until it gets to be about 75* F in the sun or ~80*F in the shade. Old school seat beads help a lot to keep my butt & back ventilated & cool

[ps2fixer]

Interesting, I swear there was a study, maybe on an older vehicle that said ac used less fuel than windows up, I thought it was done at like 55mph, but that would have been something tested probably in the 80's maybe 90's, or it's just hearsay of what someone said and it echoed along with no proof.

The other factor is, at speed windows all the way down isn't normally needed, 1/4 to 1/2 down is generally more than enough air.

The bead trick is something I actually saw growing up, my grandpa's motorhome had beads on the bucket seats up front. I don't think it had AC besides the roof top mounted one and they drove it in death valley.

My trip was mainly at 45mph steady speed, and I've drove around a bit with the windows cracked a bit and the mpg basically wasn't effected enough to really notice it. I got 54mpg on the way to the place even though that's not a perfect measurement.

I also tested EV mode a little for taking off, I went to a different post office than normal, but left my driveway and drove the 1/4 mile on gravel road in EV mode then when I got on the main road, I kicked it back to normal mode and it really used the battery a lot and seems like it used as little engine as possible. With the way this thing acts, I wonder if starting the car and letting it warm up some before taking off would be more efficient vs just starting and going like I'm used to doing for the other vehicles. I figured using EV mode would have made the engine run to move the car down the road and recharge once it started to warm up. Instead it took the battery starting off at around 55% and it drew it down to the lowest I've seen it, something like 31%. I really wasn't expecting that.

With my corolla, I could cold start it, pulse and glide the first 1/2 mile from my parent's house and by the corner I'd hit 30mpg+. From then on it would just climb farther I drove it, upper limits were around 45mpg for some trips.

I'd have to look at the hybrid computer wiring, but I suspect either the coolant temp sensor is spliced into that, or it's communicated over canbus. If I could spoof what it sees for the temp but send the correct temp to the engine computer, I should be able to make it run on the engine sooner. Of course the question pops in my head, is that a good thing or bad thing for mpg lol.

[Phase]

Amazed at how much technology has improved though since 2006 with hybrids. When using the ac in my Ioniq, at the lowest setting it absolutely drains almost no energy. Even last summer I did a 130 mile trip with the ac on and my average mpg on the whole trip was 74mpg. And that was with going thru a mountain pass. Highway driving I just used outside ventilation coming in the air intakes with everything turned off if it’s under 80 degrees with windows up. City driving if it’s under 80 I just cracked all 4 windows about an inch

It’s the same situation with my girlfriends 2020 Corolla hybrid. Ac system barely affects mpg at all and no battery drain. Extremely efficient. Would be curious if anyone on this forum has a prius prime and their thoughts with its giant battery

[ps2fixer]

Another factor is the battery age. I think that's part of why I'm not getting as high of figures compared to some others, that or my driving is really bad for mpg and driving the car "normal" is even worse lol.

I used the auto setting for the last trip. I suspect max cold and fan speed on low would be most efficient for this car.

This car also uses a NiMh battery, which charge + discharge cycle efficiency is around 80%, Lithium Ion on the other hand is more around 95%. 15% less loss in the battery all the time probably makes quite a difference just on it's own.

Before I calculated the round trip efficiency to be somewhere around 65%, I wonder how much the battery effects that figure....

90% for generator/inverter, 95% for battery charge/discharge, 90% inverter/motor which gives a round trip efficiency figure of 77% assuming there was no improvements in the electric motor/generator setup or the inverter.

Anything electrical instantly takes about 12% less energy just because of the battery tech difference based on that math.

[Phase]

yeah the ioniq battery is slightly bigger and also li-ion, plus more modern engineering and more efficent ac systems and compressors. not to mention i have the best tinted windows on the market. only thing is i wish i had gotten a white car. black is a pain