2004 - 2009 Prius Transaxle - P112 Quick Look

[@JulianFoley]

As fine an instructional video as I've ever seen. Thanks.

[@WeberAuto]

Thank you

[@TomFrostJr]

Thank you very much for these videos, especially the ones about the Generation 2, which I started watching around 2015 and which impressed me enough about the GENIOUS of the engineers who designed the Generation 2, to help inspire me to buy, in 2019, the 2008 Prius which I'm using these days. I even eventually also bought a spare Generation 2 transaxle at the junkyard with which to hopefully eventually fulfill one or another of the umpteen pipe dreams that I have of things that I think I could build with it. To nitpick on the part about the smaller motor-generator only doing a smaller amount of the regenerative while in "B" mode on the downhills, I suspect that it perhaps does a not-to-be-so-sneezed-at amount of the regeneration when you count the fact that it spins much faster. My dad's last car before he passed away in 2019 was a 2007 Prius that he'd bought brand new, and even though he'd been a lifelong professional physicist, it took your videos to REALLY impress me enough to buy a Generation 2.

[@TomFrostJr]

Oops - 2009, he passed away.

[@kens97sto171]

Awesome video as always, your explanation and cutaways on how it functions is fantastic.. I have a 2nd gen. 282k on the original battery. Doesn't leak a drop of oil. Very reliable vehicle.

[@ONEHEARTSOUNDS]

Same here, 271,000 miles. No issues, very reliable vehicle. I just got it 2 months

[@kens97sto171]

@@ONEHEARTSOUNDS Do the regular maintenance and they will last. If you just got the car.. definitely drain and refill the transmission fluid, unless you know it was done recently. It's an easy job. You need a 10mm Allen, socket and a 24mm socket. And 4qrts of Toyota World Standard ATF. You don't have to buy it at the dealer.. Walmart usualy has it... For $18 for a jug that 4qrts. You need a hose about 2 feet long and a funnel that will go into the hose. Drive the car a bit.. get the fluid hot. Let it sit a few to settle down to the bottom. You take the fill bolt out first ..always. Then the drain bolt out, drain it. Replace drain bolt. Open hood.. pass the hose down from the top. Stick it into the fill hole.. put funnel into the top of the hose.. Pour in the fluid.. Replace fill bolt.. your done. Takes 15 min. Or less.

[@ONEHEARTSOUNDS]

Thank you @kens97sto171

[@bat__bat]

I needed every bit of the information towards the end to attempt towing my gen 2 Prius. Thanks so much!!!!!!!!!

[@camfam52002]

John....among the most professional presentations I've seen....subbed!

[@WeberAuto]

Thank you! very much

[@davidmaiolo]

The 'B' mode does not appear to add any KW recharge generation at all, so you may be mistaken on its use of rotating both MG1 and MG2. I have monitored my power for years on my 2007 prius using custom PIDs in the Android Torque Pro app and 'B' only increases breaking by engine compression. A very similar thing happens once the battery is full, and you begin to coast (often happens if you are going down a long hill). Normally, there is a baseline regenerative breaking always occurring as you coast to "simulate" coasting in a normal gas engine. When your battery is full, and you coast you will hear the engine turn on and begin compression breaking like a normal car would when coasting. Throwing on B just activates this engine compression breaking before it is technically necessary (you could still use the break peddle to increase regen breaking power before the battery fills up). I think B mode is all about saving your friction breaks on prolonged downhill drives, especially for dummies that think it'll just be regen breaking the whole time. I notice I hope that explanation helps understand what B is used for.

[@automaticosdovale-cambioautoma]

Thank you for sharing your knowledge.

[@WeberAuto]

Thank you!

[@juiceofsapho]

You can have an electric motor to idle simply by leaving the stator circuit in "open" state, thereby only the voltage is induced in the coils but there is no current. Hence no torque/mechanical energy is produced by the motor in that case.

[@IgorLapa]

Excellent explanation!

[@alennovak8446]

Nice videos and explenation. Thank you. 😊

[@Mikesky10]

thank you for a great video!!!! I have a question; when the SOC of the battery is very low the force of the regenerative brake is strong right. but the force of the R.B, is proportional to the SOC? meaning as the SOC increase the force of the feeling of the car breaking decrease, the force of the RG decrease? or the the force remain the same until the SOC of the battery is full and then there are no more RG?

[@bassbone1785]

As far as the B setting goes, I would add that the engine is also used; I imagine it is used as a compression brake alongside the regenerative braking. I know the 05 prius my mother had would let the motor spin up as you slowed in the B setting, and the 2013 model she bought after it was totaled does the same.

[@WeberAuto]

Good point, especially when the battery state of charge is full. MG1 will actually crank the engine with the fuel disabled to dissipate electrical energy and use the engine's compression to slow the vehicle. Thanks for your feedback!

[@tituslatchmansingh4706]

great video

[@tongzhao8380]

To my understanding, you don't necessarily 'control' the torque from the engine by limiting the speed of MG1. The Planetary Gearset is functioning in such a way that the torques out of sun, carrier and ring have a fixed ratio to each other. T_sun : T_carrier : T_ring = n_sun : -(n_sun+n_ring) : n_ring. So it's really two systems running in parallel, while sharing the same speed on the ring gear. One system is the MG2 system; the other system is the ICE-MG1 system.

[@tongzhao8380]

Nevertheless this is a GREAT video! Just saying that how ICE works in assisting MG2 might require more dedicated explanation. I'd like to make a video explaining it some time.

[@WeberAuto]

Engine torque delivered to the ring gear is controlled by the rotational speed and direction of MG1. Try letting MG1 free spin. No engine torque will be delivered. Thanks for your feedback!

[@evanDove]

@@WeberAuto Aloha Professor Kelly, (and others).( Obviously) I am writing from Hawaii. I recently purchased a 2005 Prius, about 153K. Having fair amount of non-electric car knowledge, I have been inspired to learn about the Prius, as this one has some problems, and it would be satisfying to fix it without inordinately high expense of dealer cost to replace hybrid battery, (as was suggested by the dealer to correct a couple of low cells in the hybrid battery. The car had sat for about a month, I believe, from the previous owner, and was showing codes including PA080. I've read that corrosion on the plates connecting the individual battery cells to one another can generate a code of low cells). Anyway, that was not the main reason for this reply. In the video that this thread is connected to, (Prius P112 transaxle "Quick Look" from about two years ago - kzbin.info/www/bejne/jX2cepKDgc9kl9k) - you, (Professor Kelly), wrote in the tag/addendum at around 11:45 regarding the "B" and "D" positions on the shifters, that MG2 acted as a regenerative' braker', in the "D"position without MG1. In the 'relatively small', (compared to the slew of videos that you've created - and, by the way, thank you VERY MUCH ~ it's been good to learn from you), again, in the "relatively small' number of videos I've watched on the Prius, only MG1 has been mentioned as one that does 'regenerative braking'...and I had wondered if the words MG2 and MG1 had been mistakenly switched. But, based on some comments by others, (such as David Malolo), there appears to be some question as to how it actually works relative to the "B" and "D" positions on the shifter. Is the relationship Weber State University has with Toyota such that Toyota would be willing to clear up the answers to such questions? Again, thank you for your time and detailed work in your videos :0)))

[@tarassu]

Thanks. Actually it is very interesting, what actually happens when power electronics are offline and you spin the motor. I have Nissan Leaf and user manual prohibits towing (wheels down) while vehicle is off. Why? Does spinning motor and disconnected battery result in voltage spike? that might harm inverter?

[@WeberAuto]

Thank you! Good question. From what I can tell by looking at the internal schematics of the Toyota inverter, the current induced by the spinning rotors would make a loop through a rectifier diode, then high Wattage resistor, then back to another rectifier diode to complete the circuit. I am sure the diodes can handle the current if they are kept cool with a functioning cooling system. The high Wattage may not be rated at a high enough Wattage to handle the potentially large amounts of current from the rotors spinning at higher rpm. This, of course would burn out the resistor pack and possible lead to voltage spikes (current spikes) jumping around damaging more internal inverter/converter components.

[@tarassu]

WeberAuto If vehicle is offline it acts (rolling resistance) as it is in neutral (motor spinning, no load). at 100mph/15000rpm switching to N appears to be safe. To generate heat there must be some drag. Doesn't appear to be any. cooling pump is offline if vehicle is offline. Those resistors on Prius, are they specifically for this scenario or they do something else too?

[@WeberAuto]

It does not matter if there is drag. If you spin a magnet inside a coil of wire it will induce current proportional to the RPM, number of coil wire turns, magnetic field strength, etc. Those rotors are either a motor or a generator, there is no other option. 15000 RPM would generate a very high voltage with current proportional to the circuit impedance. Heat would definitely occur. I don't know for sure about the Prius resistor function, but I suspect they are used for this scenario.

[@sanjose101ful]

Please me help! I have 08 Prius , gas engine does not turn over , but when put in D, vehicle still moved by electric only. I am guessing it has a Transmission problem . What you guys think ? Thank

[@davidmaiolo]

Sounds like just your electric motors are working. The prius battery on full charge will maybe only move the car about a mile before completely draining, so I doubt you got very far. I doubt this is a transmission issue. If the engine isn't turning over, than it is probably some engine issue (like no gas, no compression, no spark etc). Even with a blown engine, the prius will still go to "ready" and use the electic motors. Only once it tries to fire up the combustion engine will it probably realize there is a problem and through you codes

[@jclair4617]

So neutral doesn't disconnect the engine from the wheels?

[@WeberAuto]

Neutral is just software based. The engine is always connected through a planetary gear set, but not a direct connection.

[@jclair4617]

Ok so how does a non-hybrid with a cvt do neutral, I thought it was slack in the "belt".

[@WeberAuto]

No, they have a forward clutch pack to connect the engine to the drive pulley. In neutral they simply release the hydraulic clutch pack.

[@jclair4617]

Cool, thank you.

[@billyr9840]

Nice !

[@WeberAuto]

Thank you!

[@pascalhumphrey]

do a Tundra please

[@WeberAuto]

Thank you for the feedback! See my video on the AB60E in the Tundra.

[@pascalhumphrey]

i am watching it now. very good info on your vids. keep it up