My eZuma project (Elektra)

Discussion in 'Electric Motorcycles' started by MJSfoto1956, Sep 16, 2018.

  1. MJSfoto1956

    MJSfoto1956 Been here awhile

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    Recently I was able to acquire an electric 2017 Chinese Zuma clone via Craigslist. The price was right and I was ready to bite the bullet. This bike is typical of Chinese eScooters in that it uses a fairly common 72v 2000w motor/controller platform, which limits it to 30mph top speed and 25mile range. I plan on upgrading this sorry excuse for an electric motorcycle into my go-to errand bike capable of 60mph/50mile range.

    I'll start with a photo from day 1 -- directly after picking up via Craigslist. Notice the heavy use of decorative plastics and decals. Not to my taste. Those will have to go. I like my bikes naked!

    eZuma naked_IMG7622_DxO.day1.jpg

    So 24 hrs later, my busy hands were happy to remove the extraneous decorative plastics and decals. Note: it was easy to remove the decals: 20 secs each with a heat gun was enough to loosen 'em up, then just peal away. This "bare bones" state is where I begin the journey.

    eZuma naked_IMG7622_DxO.day2.jpg

    Another thing you might have noticed: this clone is a full 6 inches longer than a true-to-form Zuma/BWs. I now have more leg room than an SMAX! ;)
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  2. MJSfoto1956

    MJSfoto1956 Been here awhile

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    First things first. One must understand the wiring you are dealing with. I spent about 2 hrs cleaning up the tangled mess that goes for Chinese wiring in these bikes. (Note: the photo below was taken AFTER I cleaned it up! :p ). At this point, I actually think I understand how most of it works! More to come...

    IMG_6262.1500.jpg

    The other thing you discover is that the Chinese "engineers" are sending 72v up to the handlebars! ("We don't need no stickin' relays!") =|
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  3. MJSfoto1956

    MJSfoto1956 Been here awhile

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    Sketch of likely future dash, showing PowerVelocity software running on 7" Samsung Tab A mounted horizontally. Also showing positioning of CycleAnalyst V3 mounted below for scale.

    IMG_6282.1280.jpg
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  4. RCmoto

    RCmoto Long timer

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    Love the project, thanks for sharing!
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  5. MJSfoto1956

    MJSfoto1956 Been here awhile

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    I'm pretty close to finalizing the choice of motor, controller, and overall wiring diagram. Here's where I am today:

    powervelocity 286-thickbox_v6h.1280.jpg
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  6. ctromley

    ctromley Long timer

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    Not sure what your plans entail, but one easy way to do a conversion to lithium is to get LiFePO batteries in standard lead-acid sizes. I know the common U1 battery is available this way, maybe whatever your bike uses too?
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  7. MJSfoto1956

    MJSfoto1956 Been here awhile

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    The next 9 months:
    1. Finish rear-end body/suspension mods
    2. test
    3. Update Controller + wiring + rear disc caliper (leaning towards PowerVelocity, but still on the fence)
    4. test
    5. Update Motor + 160/60-14 rear tire (leaning towards QS 273 V3 8kW 14" hub)
    6. test
    7. Update Battery pack
    8. test
    9. upgrade to braided SS brake lines
    10. Repaint body panels/frame, add windshield, etc.
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  8. Lesharoturbo

    Lesharoturbo Nerdly Adventurer

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    Some of these battery packs do not meet the same density you can get from individual cells. They have a few cells in a case that is the same physical size as a standard battery, but the box is not "full" of LiFePo cells. Building your own pack is almost always the best meeting for these projects .
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  9. MJSfoto1956

    MJSfoto1956 Been here awhile

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    More importantly: on a scooter, more so than on a motorcycle, space is at a premium. This is why LiPo is still high on the list in spite of lingering issues regarding fire.

    M
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  10. MJSfoto1956

    MJSfoto1956 Been here awhile

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    My plan for rear tire/hub motor which will result in an increase from 12" rim to 13" rim to which I plan on installing a 150/70-13 Pirelli or Michelin scooter tire. The difference in size is striking which you can see from the two photos.

    tire size comparison IMG_6378.v1.jpg

    tire size comparison IMG_6378.v2.1280.jpg
    #10
  11. EvrythingAwesom

    EvrythingAwesom Long timer

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    Be careful with 72V DC which can allegedly cause heart-arrest if the current goes thru your body, by touching a plus on one hand, and a minus on the other hand.
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  12. Lesharoturbo

    Lesharoturbo Nerdly Adventurer

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    When they send the 72V up to the handlebars, it is always just one side, either plus or minus. Otherwise, you end up with a short circuit and a fiery battery, which drastically shortens the battery life.

    Your are correct, anything over 60VDC is considering unsafe and should be handled appropriately.
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  13. ctromley

    ctromley Long timer

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    Actually, I've heard enough different versions of what constitutes lethal voltage that I don't know what to believe. The engineers I (virtually) hung around with during the EV hobbyist days couldn't agree on whether it was 36 VDC or 48 VDC. I had a 120 V pack in my car, 1/2 front and 1/2 back, that could be separated by big Anderson connectors. There was another Anderson in the middle of each half-pack, so when working in there I could quickly and easily ensure there was never more than 30 VDC potential on anything I was working on.

    When the automakers toyed with "42V" systems, their thinking was based on the "50 volt limit used as a guideline for electric shock hazard." (per Wikipedia, yet another version of a lethal "limit"). They are actually 36 VDC nominal systems, with charging voltage going up to 42 VDC. A 72 VDC nominal lead-acid system can go to 88 V during charge, higher if the charger is temp compensated and you're charging at low temps.

    Keep the high voltage stuff away from passengers. I don't care if it's just one side. A single failure (ground fault) can make it lethal. Always use two protection schemes. No exceptions. Running and charging are two different scenarios - the 'two protections' rule applies to both independently. And just because you can't know what cheapie manufacturers will do, make sure they didn't run everything at 72 V and ground the pack to the frame. I would hope no one would be that stupid, but you can't be sure. EVs need isolated packs.
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  14. MJSfoto1956

    MJSfoto1956 Been here awhile

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    That's my thinking. That's why I've spent so much time on the wiring diagram, keeping the 72v isolated from the 12v. (see previous post)
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  15. EvrythingAwesom

    EvrythingAwesom Long timer

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    Did you find a successful BMS for these LiFePo4 cells?
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  16. EvrythingAwesom

    EvrythingAwesom Long timer

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    LiPO???? My understanding is that they only have 100 charge cycles and in the Endless Sphere thread, many fires and gutted garages/homes.
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  17. MJSfoto1956

    MJSfoto1956 Been here awhile

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    No doubt. There are plenty of Einsteins out there who think they know everything. I did say "high on the list", not "top of the list" btw.

    M

    P.S. if you overcharge your lithium batteries then they won't last a season. The key with 3.6V lithium-ion batteries is to charge at no more than 4.1v max (LiFePo obviously less). Only a handful of "those in the know" do that.
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  18. Lesharoturbo

    Lesharoturbo Nerdly Adventurer

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    More like 300-500 cycles, depending onon dep of discharge even up to 1000 cycles to reach 70% of initial capacity. Much more to "kill" the battery completely.

    Thermal runaway is a real issue and requires meticulous battery care and packaging to reduce the risk of over temp, over charge, and puncture. But, Lipo are really light, relatively cheap and fairly high energy density, so they are used in these applications.
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  19. MJSfoto1956

    MJSfoto1956 Been here awhile

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    FYI, I'm leaning towards NO BMS. Yup. I'm serious.
    First watch this video and then discuss:


    Michael
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  20. EvrythingAwesom

    EvrythingAwesom Long timer

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    "regardless of chemistry" -- well, my 18650 desktop charger goes to 4.2VDC. Sorry, as someone who charges Lithium regularly, and an once-owner of Lithium 'cycles, Lithium Ion (not LIFEPO4) batteries won't fully charge unless you go to 4.2V. Do damage evident.

    The data is in Battery University.
    #20