Update and technical details on my PHEV project

Discussion in 'Gen 2 Prius Technical Discussion' started by pEEf, Nov 17, 2010.

  1. 2009Prius

    2009Prius A Wimpy DIYer

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    Wow! I am totally amazed. :thumb::thumb: What a great achievement!

    I am taking up your offer here. :) Could you share if you have found the following data in the "passive" CAN messages?

    • IGN (ignition timing)
    • Inverter and MG temperatures
    • MG rpms
    • 12 V bus voltage
    • atmosphere pressure
    • cat temperatures
    • cabin temperature and humidity
    • ODO and trip meters
    • cumulative MPG (on MFD)
    • miles since fill up (on MFD)
    Thank you! :)
     
  2. pEEf

    pEEf Engineer - EV nut

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    The shunt balancers I'm using are all safe and will never dissipate enough current for a fire. They simply allow top balancing. You are more likely to destroy an expensive pack if you run without BMS. Additionally, every cell string is monitored for voltage and temperature and will tell the BMS ECU if anything goes wrong. If the BMS ECU doesn't hear from all the modules constantly, then it will set a code, and also disable charge/discharge.

    You can't use someone's fire as a reason not to use a BMS, that's just silly!
     
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  3. pEEf

    pEEf Engineer - EV nut

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    At some point I'll shoot some video, but I'm low on spare time right now.
     
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  4. pEEf

    pEEf Engineer - EV nut

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    My car was never equipped with Nav, and the Map button isn't available anywhere on the CAN bus, so I went "old school". Amazingly, there are a few spare unused conductors on the "clock spring" assembly that connects all the stuff in the wheel, so I just ran some wires and modified the button assembly.

    The Engine ECM (ICE ECU) is what needs to basically be fed erroneous information to prevent ICE run, so it was the right choice for isolation. The Hybrid ECU is the "main brain" in the Prius and essentially calls all the shots, and sends and receives a lot more information than any other modules, so it wouldn't make sense to isolate it. (you'd have to pass-through 99%)

    No, I don't think I want to tackle that job, that's the bulk of the Prius right there! I've replaced the Battery ECU with one of my own design. This wasn't that difficult, but a replacement Hybrid (HV) ECU would be a monumental undertaking.

    When I get this all dialed in and have time to write it all up, I'll share the details. (there are many) But basically, the 0x038 frame is how the Hybrid ECU requests engine power from the Engine ECM, the 0x348 frame controls whether the ICE is allowed to run, warmup, and the RPM request, and the 0x3C8 frame is how the Engine ECU tells the Hybrid ECM that it wants to warm up. So if you intercept these frames and replace the appropriate values and bit flags, you can force the engine to either stay off, or spin w/o using any fuel for high speed EV-only mode. Right now I'm working on the right scaling to use as much of the battery as possible, but still have the ICE available if you need it. The Prius can do pure EV mode without using any fuel at highway speeds, but has very little left to accelerate or climb hills. (~20kw limit because of the boost converter) So the best way to do it is allow the engine to come on when you need the power, but otherwise have it using no fuel.

    You also can inhibit the warmup, by blocking the warmup requests from the Engine ECM (0x3C8), but you don't want to allow a cold engine to try to deliver any power, so I let it warm up when the speed hits 35mph unless I'm making a short or low-speed trip.
     
  5. pEEf

    pEEf Engineer - EV nut

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    The A123 cells have a nominal voltage of 3.3v, and I complete my top balance at about 260v.

    I did some experimentation and found the Prius works quite well at around 240 volts, and doesn't seem to suffer any issues and can still do over 100A of regen, so that's what I chose. The stock pack's range is quite high, even on my low mileage 2008, I saw the voltage swing well over 260v on hard regen.

    The boost converter is the limit on the Prius, but it's also got a current limit, so by having a higher voltage that insures that I get the most wattage through the converter, and the efficiency goes up with the smaller delta.
     
  6. planetaire

    planetaire Plug in 20 kWh 85 km/h or > 208km range

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    When driving with Nimh, a nominal Soc (63%) and no current, the voltage is betwen 220 and 230v. Not 201v.


    240v is at the beginning of your travel.
    How much Ah do you use before canceling Ev mode and what is the voltage then ?
    For long travel when do you use Battery energy ? Low speed ? Begenning so you will have room for regen ?

    (The maximum i ever saw where: 170v to 270v, +100A to -200A on different Prius 2006-2008.)

    Thank you very much, pEEf :)
     
  7. pEEf

    pEEf Engineer - EV nut

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    After settling several hours after the charge, my trips start out at about 255v and then slowly run down to 235v. I clock about ~25ah out (10% SOC) before I revert to standard Prius mode, and then I allow close to a kwh of pack use where I report 40-70% SOC. When I'm right off the charger, (260v & 100% SOC) my Batt ECU does not allow much regen, and forces EV mode until it's down to about 99.5% then it allows full regen.

    If it's a short trip (and don't need heat), I just leave it in full EV mode until 10% SOC then it does a warmup and becomes a normal Prius. If I'm going farther, right now I simply report 75% SOC and leave it in Prius mode. This basically pulls a constant 20-40A off the battery to assist the ICE, and typically will get over 99.9mpg if you drive carefully (assuming highway). I still need to do some work to get a better "hybrid hybrid" mode, and allow use of the ICE in EV mode if I need more power. Right now it's all manual, which works, but not as cool as it would be if it was automatic.
     
  8. Flaninacupboard

    Flaninacupboard Senior Member

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    pEEf, do you know how much (if any) of your work will be applicable to the gen3? I know there are some changes, but i assume the overall architecture is similar.
     
  9. jdh2550

    jdh2550 Co-Founder, Current Motor Company

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    Thanks a million pEEf. The pointer on those CAN frames is great. That gives me much to work on (combined with other information from other sources).

    BTW - newbie mistake. Everywhere I said "hybrid ECU" (hECU) I meant "battery ECU" (bECU). So, I was thinking the bECU would be on it's own bus and I wasn't aware that there was a separate hECU and ICE ECU (iECU). I figured the actual hybrid ECU was an expanded iECU. ***wrong!!!!***

    I've obviously still got a LOT to learn (which is what makes this so much fun - dang day job keeps getting in the way though...).

    Again - many thanks. I promise I shall stop bugging you for a while now...
     
  10. pEEf

    pEEf Engineer - EV nut

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    I haven't really looked at a Gen3, but I have spent some time with a Hybrid Camry which I've been told is similar. In that car they have eliminated the separate Engine ECM and Hybrid ECU and instead have combined the functions into one ECU (Hybrid Vehicle ECU). Also, the inverter now has only digital signals in/out, there are no analog signals that run into the HV ECU as on the older systems. If that's the case, then my trick for getting high speed EV mode is not going to work, as you don't have the 2 separate ECUs to alter messages between.

    They have also eliminated the Battery ECU and instead have a (similar) device, but it's called a Battery Monitor and does not sit on the CAN bus, but instead has a dedicated comms line right into the HV ECU. The Inverter also has dedicated digital comms lines, so they've eliminated the critical CAN bus messages I would imagine.

    This also means that Gen3 may not be spewing all the cool high-rate passive data,which sucks for my instrumentation system.

    On top of that, I don't like the Interior at all and the exterior styling looks too much like they hired Cadillac's stylists. :eek:hwell:
     
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  11. planetaire

    planetaire Plug in 20 kWh 85 km/h or > 208km range

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    Thank you, pEEf

    But when you have only 10% Soc your voltage is 235v that is 3,26 v per cell. It look high regarding A123 discharge curve, i believe ?

    About your super ev mode: did you cut some wire between Hybrid Ecu and Ice Ecu and insert some electronic device (like a pic) to intercept the request power message or send a second message modified just after the power request?

    :)
     
  12. imwoody36

    imwoody36 the prius parts guy

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    After repairing 3 collision damaged 3rd Gen pruii...I agree with pEEf.
    they have 3 times more little parts in front of the engine making repair 3 times more costly. sort of like the difference between a Toyota and a Lexus. ( or a Ford and a Lincoln). I firmly believe the 2nd gen prius will be on the road longer than any of the 3rd gens.
    The 3rd gen prius is built to be replaced.
    therefore...keep working on the current project.
    ( btw I sold my 2010 and got back into an 08)
     
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  13. pEEf

    pEEf Engineer - EV nut

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    FYI Toyota calls the ICE ECU an "ECM" (Engine Control Module) and the "main brain" in the Gen2 is the Hybrid Vehicle ECU or HV ECU, but I guess hECU is fine.

    The HV ECU makes all the decisions in the Prius, it's where the Accel pedal feeds into and it receives info from the Battery ECU on the CAN bus, and it talks to the ECM and tells it how much engine power it requires. It also listens to the ECM for warmup requests, etc.
     
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  14. pEEf

    pEEf Engineer - EV nut

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    That's the open-circuit voltage. It will indeed sag lower. I do not use voltage as any kind of SOC indicator, I count coulombs.

    I didn't cut anything. There are 2 CAN bus bridge connectors in the Prius, so if you disconnect these, you can isolate every device on the bus. There is one located in the right side kick-panel that isolates the ECM. I simply pulled the 2 CAN H/L wires from this connector and ran them back to my new Battery ECU where it has it's own CAN port. The battery ECU receives frames from the HV ECU and either modifies them (Full EV) or sends them as-is (Normal mode). Additionally, it listens to the ECM and does the same thing in reverse for messages destined for the HV ECU. (i.e. Warmup requests)

    What greatly helped my analysis of the CAN bus was to build a dual-port logging device. It hooks into any ECU between it and the CAN bus and passes all frames as-is through the device, but it allows me to see "who said what" and having that info makes it much easier to reverse-engineer the messages.

    If I didn't already have the battery ECU in back, I simply would have put a device right up front so I didn't have to run the extra shielded twisted-pair.

    The 2 CAN bus junction connectors are of great value for learning! 2 points where you have access to every individual device on the bus.
     
  15. pEEf

    pEEf Engineer - EV nut

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    Response from another thread:

    Thanks, Yes I know the PHEV stuff (especially done as I did) has a limited market, but a Monitor (Priuscan) has a much wider market and can benefit more people. Plus, you pretty much need it (or something similar) if you have a PHEV.

    I too am using an old Brusa NLG4 that's been modified. It puts out 3.5kw @ 240vac for a ~2 hour charge and can still plug into 120 for the slow charge. Brusa makes great stuff, too bad it's so expensive.

    I agree on the large-format lithiums. The reason I used A123's is because I got them from another project. Thundersky's have come a long way! I think I'd use the 40ah as well.
     
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  16. jdh2550

    jdh2550 Co-Founder, Current Motor Company

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    Interesting to hear you say your work has a limited market. In some ways I think it's got a much larger market. With the Volt coming on the scene and such a large number of gen 2 Prius on the road I would have thought your PHEV conversion looks quite favorable. It's a very well integrated solution - one that anyone could use (especially with possible refinement on the software - which I believe you said you were working on). The Volt is a 40 mile capable plug-in for about $40K (right?). I would think your kit could be sold for <$10K (with a switch to different cells - GBS may be a better choice than TS)

    If you ever do consider wanting to work with a manufacturer for a PHEV package please consider contacting me (john ~ currentmotor ~ com). I'd love to see a solution like yours sold "a la carte" rather than insisting on having to buy the whole enchilada from one source. Also, I think this is exactly the sort of project that can support being open source as well as having (limited) commercial viability. This comes from the fact that although one could make the software and hardware schematics available that's still a long way from a successful implementation.

    All this is just armchair quarterbacking. I hope to be able to replicate your work starting next year sometime. BTW - look at this for a nifty tool: Atmel Products - AVR Solutions - UC3C-EK it has dual can interfaces, integrated touch screen - a whole BUNCH of other stuff. All for $299: http://store.atmel.com/PartDetail.aspx?q=p:10500191;c:100113.

    I'm off to read up on your thread about Priuscan...
     
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  17. lopezjm2001

    lopezjm2001 Senior Member

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    Hi pEEF,

    I am totally amazed by what you have managed to have done. There are many of us with an Enginer 4KWH system and would love to have a box that would intercept canbus messages between the Hybrid ECU (or HV ECU) and the Engine ECU (or ICE ECU) and change them so the Prius could run at a higher speed EV mode >> 44km/h and also to inhibit warmup. I think there is more of a market for this than a Priuscan monitor.

    I would like to know what kind of device does the intercepting of canbus messages and change them. We all would like to know about the programming that would go into doing this.

    I don't think my ScangaugeII has the ability to capture these messages and change them. What is the best device I could get to read and learn about Prius buscan messages, maybe Canview? Can you recommend a book/manual or a website to learn about Prius canbus messages. So far I know that canbus is a high-speed serial communication across two wires which allows any device to communicate to any another device hooked up to the canbus. Each device has it's own address.

    I fail to see what point there is for having a Priuscan monitor unless it does the functions above of increasing max EV speed and inhibit warmup.

    I certainly would buy one these if it could increase the Prius EV mode maximum speed and inhibit warmup (let it warm up when the speed hits 35mph in blended mode). I definitely think there is market demand for this. The device would be relatively small, cheap and easy to manufacture and it might just be a matter of plugging it into the prius OBDII socket - plug and play.
     
  18. sub3marathonman

    sub3marathonman Active Member

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    I too am wondering what pEEf is using. It is spectacular work that he is doing. It sounds like he has just set up a small computer to do it, but I'm not sure.

    The only method I've seen for actually modifying the CANbus messages as a stand-alone product is "Flowcode CAN system" that Jim Fell in England used for his Prius conversion: How to get 100mpg from your car - The IET

    mrbigh also added, "The conversion concept of Jim Fell is based on the PriPrius conversion type by Rich Rudmann. I demo this PHEV conversion in my 2004 Prius at Hybridfest 2007 in Madison, Wisconsin with sealed AGM's." Here is the link to read his comments: http://priuschat.com/forums/prius-p...rticle-pimping-prius-nuts-volts-magazine.html . I don't know what mrbigh is using in his conversions as far as the CANbus goes.

    The main problem I saw with the "Flowcode CAN system" is the price of $522. Here is that link: http://microcontrollershop.com/product_info.php?products_id=2363 . You're also probably going to need to buy their Flowcode programming book for another $55 too.

    Jim Fell figured out how to program the system, so it isn't just plugging it in either. I don't know how difficult that was, he said it was straightforward.

    I found this: http://www.phytec.com/products/can/pc-can-interfaces/peakpci_expresscard.html from Phytec, which will hook up to the CANbus, but I don't know if you can only monitor the CANbus or if you can also send messages over the CANbus. It seems to me that you need to have a CANbus "in" connector and a CANbus "out" connector to the computer, or you will break the CANbus connection with whatever device you're trying to monitor.
     
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  19. mrbigh

    mrbigh Prius Absolutum Dominium

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    To enlightening the followers of this thread about sub3marathonman question:
    I'm using Hybrid Interfaces CanView4 and the BMS+ with Monitor+ equipment as a total package for my PHEV conversion, already in the 5th year running :focus:
     
  20. sub3marathonman

    sub3marathonman Active Member

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    I knew the Hybrid Interfaces CanView4 would monitor the CANbus, I just didn't think an individual could use it to send their own messages on the CANbus.
     
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