Replace battery pack in Out of gas mode

Discussion in 'Prius PHEV Plug-In Modifications' started by menardsy, Oct 25, 2013.

  1. menardsy

    menardsy Junior Member

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    Hello again,
    From my previous post where I had an idea about using ebike battery, I had 2 other ideas.
    1st idea:
    use 8kwh battery bank with 3 enginer / MD-TECH converter (would give 15kwh) in out of gas mode. Since the power would mainly come from the lithium battery, the HV nimh should not overheat too much.

    Possible problems:
    • HV battery overheat
    • Prius inverter overheat
    • Prius computer malfunction


    2nd idea

    Instead of using the Prius HV nimh battery pack, use a lifepo4 with the same voltage as the stock HV pack. With a relay, disconnect the stock HV pack, connect the LIFEPO4 instead of the HV pack, put the car in OOG mode.

    Possible problems:
    • LIFEPO4 battery overheat
    • Prius inverter overheat
    • Prius computer malfunction
    What do you think?
    Sylvain
     
  2. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    More possible problems
    * The ECU's are looking for Nimh batteries aka 7.2-8.X volts. LiFePo4 = 6.5-7.3. To make the ECU happy, you would have to keep the lithiums at full charge all the time or spoof the ECU.

    There are so many other problems to this. First of all, have you ever driven the Prius in OOG mode? Here are my thoughts. I tell them to you not to try to discourage you but to let you know what you're up against.

    The Prius in general (Plug In excepted) is not a good candidate for "PHEV" conversion. Here's why:

    1) It is designed as a gasoline (primary) car with electric assist. It is for this reason that the electric motors do not have enough power to safely propel the car. With electric mode only, the car is seriously underpowered and not safe to drive on the streets (IMO)
    2) The Prius has advanced, high-tech monitoring systems (called ECU's) that all work together to make this engineering marvel work. Adding more battery capacity or switching to lithium requires modifying what one ECU sees which causes multiple problems with other ECU's.


    The old adage that "every time you fix a problem you have to solve another" has major application here. A typical scenario may go like this:

    Problem/Fix: The battery runs out or low in "EV" mode, I need a bigger battery (thousands of dollars)
    New problem: Adding a bigger battery requires spoofing or/reprogramming the Battery ECU
    Fix: Then I will reprogram/spoof the ECU so I can use the bigger battery (hundreds of dollars)
    New problem: Now that I have this bigger battery and the ECU spoofed, the ICE still wants to come on when I accelerate normally
    Fix: I can use OutOfGas mode to stop the ICE from coming on (cheap)
    New problem: The stock electric motors/inverter setup are not strong enough to power the car in most situations and... if I want to use the ICE, I have to pull over, turn the car off and then back on to allow the ICE to be used (then you have the above problem of the ICE coming on too much)
    Fix: I need to install a larger electric motor (thousands of dollars)
    New problem: The inverter cannot power the new motor
    Fix: I need a new motor controller/inverter (thousands of dollars)
    New problem: I've spent so much money on converting my Prius that there is no return on investment and I can't sell it b/c noone wants a car that's had this many mods
    Fix: I need to take every mod off and return the car to its original state (thousands of dollars)

    (It reminds me of a story I heard in grade school where a king had mice in his castle and wanted to get rid of them. So... he brought in cats then, he had too many cats so... he brought in dogs. This continued until he brought in elephants. Having too many elephants, the only thing he could think of to get rid of the elephants was mice. He brought back the mice, the elephants left and he lived happily ever after)

    There are other numerous reasons why the Prius shouldn't be converted unless you're going to gut the HSD and add an electric drive system that can handle the requirements. The stock Prius electrical system cannot handle the requirements on its own. It needs the gas engine and the gas engine needs the electrical system. They have a symbiotic relationship.
     
  3. menardsy

    menardsy Junior Member

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    Thanks, I didn't see all the problem it could cause. I finally bought a MD-TECH PHEV conversion kit. It will not allow the car to run in electric only mode all the time, but I sould be able to run the car in EV mode up to 34mph with the EV button (that I already have and like much). My daily commute is 7 mile and last about 30 minutes, so I should be able to run in EV mode most of the time...
     
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  4. bisco

    bisco cookie crumbler

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    sounds interesting! do you have a link?
     
  5. lopezjm2001

    lopezjm2001 Senior Member

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  6. bisco

    bisco cookie crumbler

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    thank you jim! just read the thread, ouch, all the best menardsy!
     
  7. bisco

    bisco cookie crumbler

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    4,800 euros = $7,000.?
     
  8. menardsy

    menardsy Junior Member

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    Well, the site say 3500 euro...Md tech sell the product at 3000$us...
     
  9. menardsy

    menardsy Junior Member

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    I must admit that I am taking. However, after several conversation with Sushil from plughybrid.de, it help me to be more confident in the product. Only future will tell if this was a good decision. My kit should be here near christmas .
     
  10. bisco

    bisco cookie crumbler

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    thanks, i didn't realize everything came in the kit, i was adding all together. why does it take so long to get?
     
  11. lopezjm2001

    lopezjm2001 Senior Member

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    Congrats on your purchase. From what I have seen this kit is superior to the Enginer kit.
    But I have yet to see the improved design pan out in reality over time. Your kit would be the first reported buy on this forum. Please keep us informed on how it performs over time. I am sure other potential users would be interested in your kit's performance over time.

    How much was the delivery to Camada?
     
  12. menardsy

    menardsy Junior Member

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    I think it has something to do with items out of stock. I suppose they don't produce to much system in advance since the market is perhaps to small.
     
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  13. menardsy

    menardsy Junior Member

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    I am also curious to evaluate the kit and report it back to Prius Chat. If the kit is reliable, it would be a second chance for people wanting to upgrade their Prius.

    I didn't receive the Shipping price yet, but I think it around 1000$ US. So for 4000$ I should have a kit, hopefully with not BMS / charger / Overheating problem. I think this price is the right price for a reliable system.


     
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  14. menardsy

    menardsy Junior Member

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    Hello everyone it's been a long time since I didn't give feedback about the kit from MD tech. It's been nearly six month I'm using it and no problems so far. The kids is really quite reliable. I'm getting around 2.0 l/100 km. The kit have been overheating this summer. Usually it is about 3 that gets over 40 degrees Celsius. At this point the bms is disabling the converter to protect the batteries. But with the upcoming winter I don't think it will be much of a concern.

    I'm waiting for a second converter to arrive. It's been nearly a year I'm waiting for me since I ordered it.

    I am trying to use it in parallel with the other comforter to increase the power. Hopefully it will be enough to run in oog Mode.
    So far I'm really happy owner of this kit.
     
  15. bisco

    bisco cookie crumbler

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    congrats, thanks for getting back to us! what do you mean by, 'no problems so far' and 'the kit have been overheating this summer'?
     
  16. menardsy

    menardsy Junior Member

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    Well what I meant is that the kit is getting hot but its no getting damaged because of the protection. I'm thinking about installing an aluminium liquid cooling block with a radiator.
     
  17. bisco

    bisco cookie crumbler

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    gotcha, thanks! what is oog, electric only?
     
  18. menardsy

    menardsy Junior Member

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    Oog is the acronym for out of gas mode... I tried it yesterday it was quite fun to go over the 34 mph ev limit. ..
     
  19. bisco

    bisco cookie crumbler

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    cool! how many miles of ev are you getting?
     
  20. lopezjm2001

    lopezjm2001 Senior Member

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    Have you noticed any loss of range over the six months?
     
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