Over Discharging A Shorai Battery

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Rockwell, Nov 19, 2012.

  1. Rockwell

    Rockwell Been here awhile

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    Anyone have experience over-discharging a Shorai battery?

    I just read on their website that you should not allow the no-load voltage to go below 12.8V. My battery reading, read from within TuneECU, under some load (headlights, ECU) was 12.1V.

    I didn't have a handheld volt meter handy, so I couldn't get a reading of the no-load voltage.

    What is a typical battery voltage under the load of the headlights and ECU?

    How long do these Shorai's typically take to charge (say from 50% charge)?
    #1
  2. sonoran

    sonoran copacetic

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    If you discharge below 10v then you risk permanent damage to the cells.

    DAMHIK.
    #2
  3. AdvGa

    AdvGa Long timer

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    Here is a general chart of the battery charge:

    http://rvroadtrip.us/library/12v_system.php



    <CENTER><TABLE dir=ltr border=1 cellSpacing=1 cellPadding=0 width=396><TBODY><TR><TD vAlign=center width="33%">
    State of Charge​
    </TD><TD vAlign=center width="33%">
    12v Battery​
    </TD><TD vAlign=center width="33%">
    Volts Per Cell​
    </TD></TR><TR><TD vAlign=center width="33%">100%
    </TD><TD vAlign=center width="33%">12.6+
    </TD><TD vAlign=center width="33%">2.12
    </TD></TR><TR><TD vAlign=center width="33%">90%
    </TD><TD vAlign=center width="33%">12.5
    </TD><TD vAlign=center width="33%">2.08
    </TD></TR><TR><TD bgColor=#00ff00 vAlign=center width="33%">80%
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">12.42
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">2.07
    </TD></TR><TR><TD bgColor=#00ff00 vAlign=center width="33%">70%
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">12.32
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">2.05
    </TD></TR><TR><TD bgColor=#00ff00 vAlign=center width="33%">60%
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">12.20
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">2.03
    </TD></TR><TR><TD bgColor=#00ff00 vAlign=center width="33%">50%
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">12.06
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">2.01
    </TD></TR><TR><TD bgColor=#00ff00 vAlign=center width="33%">40%
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">11.9
    </TD><TD bgColor=#00ff00 vAlign=center width="33%">1.98
    </TD></TR><TR><TD bgColor=#ffff00 vAlign=center width="33%">30%
    </TD><TD bgColor=#ffff00 vAlign=center width="33%">11.75
    </TD><TD bgColor=#ffff00 vAlign=center width="33%">1.96
    </TD></TR><TR><TD bgColor=#ffff00 vAlign=center width="33%">20%
    </TD><TD bgColor=#ffff00 vAlign=center width="33%">11.58
    </TD><TD bgColor=#ffff00 vAlign=center width="33%">1.93
    </TD></TR><TR><TD bgColor=#ff0000 vAlign=center width="33%">10%
    </TD><TD bgColor=#ff0000 vAlign=center width="33%">11.31
    </TD><TD bgColor=#ff0000 vAlign=center width="33%">1.89
    </TD></TR><TR><TD bgColor=#ff0000 vAlign=center width="33%">0
    </TD><TD bgColor=#ff0000 vAlign=center width="33%">10.5
    </TD><TD bgColor=#ff0000 vAlign=center width="33%">1.75
    </TD></TR></TBODY></TABLE></CENTER>
    #3
  4. Rockwell

    Rockwell Been here awhile

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    Here is the chart for battery charge from the Shorai website:

    [​IMG]

    The voltages given are no-load voltages.

    My battery is an 16AH battery. I am wondering if I could have gone form fully charged to below 10% in about 30-40 minutes with a load of the dash, ECU and headlights.

    This would mean that 18AH would have been used up, or 32A-24A for that 30-40 minutes.

    My headlight is 55W - at 12V that's 4.5A.

    I don't think the ECU and dash would draw the remainder of the current.

    Hopefully, I am just paranoid. I'll have to wait until morning to see.
    #4
  5. dogsslober

    dogsslober No neck tie, Ti neck

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    I left my key on one day after lunch, worked tell 3:30 and it would not start. Got a jump from a coworkers truck. My shorai is still working well. This happened 3 months ago.
    #5
  6. LukasM

    LukasM Long timer

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    The Shorai batteries are not rated for their true Amp hours, they are rated for their equivalent starting power.

    You should really get yourself a headlight switch with an off position.
    #6
  7. Dustodust

    Dustodust Long timer

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    last july I left the headlight on overnight on my 525exc with Shorai 12 , next day was dead as could be, no measurable voltage , I charged it on the deltran for about 10 hours and it has been working great ever since
    #7
  8. crazybrit

    crazybrit Long timer

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    Is there anything special about the Shorai vs the Turntech (other than capacity)? I thought they were the same underlying chemistry. I know the Turntech has no over discharge protection.

    During a TAT trip last year my buddy left his headlight on (45 mins) on his new 5A/h Turntech. It would crank, borderline to start but wouldn't start. He then fatally ran it down further trying to start the bike. Over the following year it's got progressively more useless and on last months trip was always needing to be jump started.

    Not trying to argue with the above stories of success after recharging, just curious. It's been one of those things that has kept me from considering one.
    #8
  9. Balsta

    Balsta Been here awhile

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    +1
    thought I killed my Shorai the summer 2011 and the Voltage was 9 V only. Since the Shorai charger at first effort did not bring it alive I gave it some chock treatment with my automobile battery and then filled it up with the Shorai charger. Worked fine ever since. Anyway I find now a year and a half later that the charger wont fill it more than 14.0 Volt and I'll buy a new Shorai this winter. I'll never buy any cheap lead/acid batteries again since these may be everything from just fine until dead from day one. No more milliondollar YASA either.
    #9
  10. knobbyjoe

    knobbyjoe Adventure and dirt rider

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    My thinking

    I've killed a Turntech and a Shorai. I'm not going to get another one of these type of batteries until I see some changes. Like...

    Smart battery that will protect itself from overcharging or discharging. :norton
    KJ
    #10
  11. crazybrit

    crazybrit Long timer

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    Supposedly not enough room in the case for the (necessary) electronics. Always seemed an odd reason given how compact electronics are these days.
    #11
  12. genghis9021

    genghis9021 Arak Connoisseur

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    Yeah - that story is the epitome of "that dog won't hunt". The capacitors and inductors required to have a "good" charging circuit are TEENY !

    Yes, it IS a more complicated circuit when your balancing MANY cells, often not in a strict "all parallel or all series" arrangement as is almost always the case . . . another Shorai "story".

    ANY lithium cell, once significantly drained is permanently compromised. It's chemistry (or physics, if you prefer).

    Me, I ride Anti-Gravity batteries after a failure of a Shorai after just 6 weeks . . .
    #12