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Thread: What You Shouldnt Do When Building a EV

              
   
   
  1. #1
    Ghost Rider Allen_okc's Avatar
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    What You Shouldnt Do When Building a EV

    Im here before everyone to say, i messed up - for this example i hope i may help others not to make the same mistake...

    first of all, it took me a year and a half to build my motorcycle from scratch, completely from nothing. all i had was the front forks off a Honda Magnum, and from that i built a motorcycle...

    because of my budget i bought 8 cells every pay day when i could afford it, so i could build my 24S3P 72 volt headway cell battery pack - i did individually charge each cell prior to assembly...

    i fought the state of oklahoma to recognize my motorcycle as a vehicle, it took about six weeks to do that...

    i test rode the bike several times, and only charged the battery pack once with three 24 volt lithium battery chargers...

    after all that, out of my excitement i wanted to ride my motorcycle home, and i did so without making sure that all the cells where evenly balanced and fully charged before hitting the road with my new EV motorcycle...

    well you can imagine the damage i did to the battery pack - i fried 17 cells, four of which vented and/or leaked liquid, the pack now has a sweet smell about it,

    i have 55 cells left out of 72 that seems like they are in good shape...

    but i will applaud the fact that the headway cells did not catch on fire or burn the bike to the ground. i was very impressed that it didnt...

    four cells test at zero volts, and the rest of the fried cells read .2 volts, none of them caught fire...

    im writing this so the newbies may learn from my mistakes - if you cant afford these cells, then use agm batteries till you can afford to have LiFePo4 cells and totally understand them and have them set up proper...

    completely stay away from Lipo cells cause, if i did what i did with Lipo cells, i wouldnt have a motorcycle anymore either...

    comments and face slaps to me are welcomed, i deserve it...
    The Greatest thing about a EV, is the Song of the Terrain...

  2. #2
    Ghost Rider Allen_okc's Avatar
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    now for my stupid question - i have 55 cells left - could i bring the pack down to a 24S2P set up and still have a decent amount of power for my motorcycle???
    The Greatest thing about a EV, is the Song of the Terrain...

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    Senior Member Skeezmour's Avatar
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    Bike still looks freaking awesome man. You will be back up and running in no time. A bit wiser too.

  4. #4
    Senior Member Skeezmour's Avatar
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    Quote Originally Posted by Allen_okc View Post
    now for my stupid question - i have 55 cells left - could i bring the pack down to a 24S2P set up and still have a decent amount of power for my motorcycle???
    Yes you can I would just not be really heavy on the throttle like that. Low speed take offs would be fine with that setup.

  5. #5
    Ghost Rider Allen_okc's Avatar
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    i hear you Gene - and thank you for the advice today, i will definitely do what you told me to do, so this doesnt happen again...
    The Greatest thing about a EV, is the Song of the Terrain...

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    That sucks. Glad to hear you weren't hurt and the bike still works fine.

    I'm curious, How do you keep that from happening again, other than just be super vigilant about how balanced the charges on the batteries are? Is this what a BMS is for?

    Sorry for asking so many questions, but I'm a complete noob, first post even. I've been planning my own build for a few weeks now. Of all the things that could go wrong, this has me the most worried simply by the virtue of it being easy to do and has catastrophic and expensive consequences. Or am I worrying too much?

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    Senior Member jonescg's Avatar
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    It sounds like the self discharge rate of those cells was particularly high. I wouldn't have thought that they would be that far out of balance, but it seems there were some which were almost flat when you took off. Still, as you already attested, making sure they are all at the same state of charge before taking off, is a good move

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    Empulse R #24 frodus's Avatar
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    Re: What You Shouldnt Do When Building a EV

    They don't ship em full either. So you really need to equalize them all before installing.

    Tough break man. Hope you can pick up the peices and keep goin
    Travis

  9. #9
    Old EV Racer EVcycle's Avatar
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    You are not he first one to do this. When we started with Headways, the original Packs that were sent
    had BMS units, but were not set up for the amount of juice we were wanting out of them. I have a box of "Headway Paperweights"
    I use to show folks what the cell looks like. It is Winter (check local listings), take your time and build up the
    battery packs again so in the spring, you have have a fun ride again.

    New Headways not only need to be balanced, but I have found that the first 20 charges/discharges need to me no more than 50% discharged.

    Also another protection item is the controller. Program it (if possible) to shut down well before the 2.0v minimum
    on headway's. Saved me at least once.
    Last edited by EVcycle; 15 November 2012 at 0301.
    EV Ed
    Never let being a responsible adult get in the way of passion and curiosity.
    Motenergy.com
    Ev album 2456, 2458, 2457, 2681, 3456, 3630, 5511, 5512

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    Senior Member picaroon's Avatar
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    Dont be too hard on yourself as it sounds like a rock 'n' roll way to ride your cool looking chopper for its first legal ride :-)
    Well done on getting it built and legal, and good luck putting it back together

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