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Thread: Custom LiPo GPR-S

              
   
   
  1. #1
    o_O
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    Custom LiPo GPR-S

    I bought JK's custom built GPR-S which uses LiPo pouch cells. It's a 22s3p configuration for a nominal 80v and 60Ah. The EIG cells support 5C continuous (300A for the pack) and 10C peak for 10 sec (600A). The controller & motor can only handle 300A, and the max reported by the CA is 275A.

    The bike pulls hard and doesn't slow down. Reminds me of the leads I had initially, except this has usable range to boot. It hits 70mph on the flats and is able to sustain that speed. The power-weight ratio is superb, reminds me of the YZF600. Call me delusional, but I'd wager this setup could have placed well in last year's TTXGP. Probably not this year as the bikes have improved, though more cells and a beefier motor/controller could make it competitive. In any case, it's hella fun to ride.

    I believe Harlan (Hollywood Electric) helped him assemble it using a barebones kit from EMS and adding the LiPo cells. Harlan also has a LiPo modified GPR-S which I hadn't heard about it until JK listed his bike. Maybe Harlan is too modest to brag about the pioneering LiPo work he's done

    EIG specs at http://www.eigbattery.com/eng/product/3.jpg and also attached in this post. The more interesting bits:

    Vnominal 3.65v
    Vmax 4.15v
    Vmin 3.0v (recommended, though they also list 2.5v as the absolute lowest)

    Capacity 20Ah
    Discharge 5C (continuous)
    10C (up to 10 sec)
    Cycle life 1000 @ 100% DOD

    I find it interesting that although it's "only" rated for 1000 cycles, that spec is at 100% DOD. If I recall correctly cycles for LFP are spec'd at 80-90% DOD. It'd be interesting to see what the LiPo cycles would be at 80% & 90% DOD instead of 100%.
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  2. #2
    Empulse R #24 frodus's Avatar
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    Really awesome build! Love the bike.

    got an extra cell i could borrow to test?
    Last edited by frodus; 18 January 2011 at 2010.
    Travis

  3. #3
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    That bike is the best GPR-S set up I have ever seen. A very clean assembly. Congratulations Chef.

  4. #4
    Old EV Racer EVcycle's Avatar
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    300 amps pulling hard and a RT motor?....who would have thought?


    Nice looking setup. Congrats!
    EV Ed
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  5. #5
    teddillard
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    Quote Originally Posted by EVcycle View Post
    300 amps pulling hard and a RT motor?....who would have thought?
    ...didn't get past me either.

  6. #6
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    I figure with the increasing availability of large LiPo cells and the various builds going on, it would be convenient to have a reference to compare against. I'll be testing the bike more as soon as the darn cedar pollen clears out of here in a few weeks.

    An interesting characteristic of LiPo's is the discharge voltage has a mostly linear slope from 4.0 - 3.4v (1C) before it hits the knee. That makes it easier to track capacity by eyeballing the voltage. Not as precise as counting Ah's but it's always handy to have another metric to check against.

    Also interesting is that at continuous 5C, the capacity only drops to 95% (or 19 out of 20Ah).

    Quote Originally Posted by teddillard View Post
    ...didn't get past me either.
    *whoosh*

    What I would love to see, given the finances, time & wherewithal, is to put these cells in the GPR-S with the Sevcon and D&D SepEx. The Sevcon handles 420A peaks; the D&D is a monster and I bet can handle that much or more. That ride would be a rush.

  7. #7
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    From what I have seen of my D&D motor's power curve, it would be happy with 400-500 amps. On the other hand, I do wonder how long it could handle that current without getting red hot. Even when sucking 150 amps for a few minutes, my motor gets quite hot to the touch. However, I sure would like to experience what it would be like for the D&D to be performing at its maximum.

  8. #8
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    Well, I'll be running lipo, two Powerpaks with series-parallel switched D&D sepex's. Lemme know if you guys are around Purdue this spring.
    "We realize that we have not answered all your questions and in most cases, our
    answers have only served to produce more questions for which we have no answers,
    leaving us as confused as before. However, (we believe) we are now confused on a
    much higher level and about much more important things than before."

    1978 Suzuki GS550 - 48V 60Ah Pb-A, Alltrax 4844, Etek-RT
    1997 Suzuki Katana 600 - 18s8p (~72V, 40Ah) 30C Turnigy Lipo, Navitas 500A with D&D Sepex

  9. #9
    Empulse R #24 frodus's Avatar
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    Quote Originally Posted by Richard230 View Post
    From what I have seen of my D&D motor's power curve, it would be happy with 400-500 amps. On the other hand, I do wonder how long it could handle that current without getting red hot. Even when sucking 150 amps for a few minutes, my motor gets quite hot to the touch. However, I sure would like to experience what it would be like for the D&D to be performing at its maximum.
    motor side amps right? 4-500 battery amps is a ton.... be surprised if you could hold on.
    Travis

  10. #10
    Empulse R #24 frodus's Avatar
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    Quote Originally Posted by Tony Coiro View Post
    Well, I'll be running lipo, two Powerpaks with series-parallel switched D&D sepex's. Lemme know if you guys are around Purdue this spring.
    how the heck is that gonna work?
    Travis

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