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  1. #1
    cap10b's Avatar
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    Uneven Batt voltage draw

    Robert,
    I have a smart fly EQ10, Smart Fly Pro, and Sport all on A123 direct with no regulator plugged into my Airtronics 2.4 10channel and 8 channel receivers and they work flawlessly. No problems noted. However I noticed on my 39% plane running 8 JR 8611a servos I was getting uneven amperage draw on one of the batteries. I decided to add another pack (I run all A123 with no regulator) and this solved the problem. Now I recently put my Smart Fly sport into use on one of my 50cc planes running all analog high power metal gear servos and again with my 8 channel 2.4 receiver. All works great but again I am experiencing uneven current draw. Is this normal ?

    Thanks

    Johnny Snead
    I ran out of Altitude, Airspeed and Ideas !

  2. #2

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    RE: Uneven Batt voltage draw

    Hi Johnny,
    With A123 packs this is not uncommon, especially at low battery discharges (<30%). A123s have such a low impedance they do not equalize in voltage as well as other battery types. A123 packs MUST be balance charged and a lot of chargers do not balance the A123s well. You should consult the Fromeco website for the chargers they have tested that actually do a good job of balancing A123s.
    Robert Ritchey
    Owner, Smart-Fly
    www.Smart-Fly.com

  3. #3
    cap10b's Avatar
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    RE: Uneven Batt voltage draw

    Robert,
    Thanks for the quick response, to be honest I do run a balancing charger and I do balance my charges almost every time. But recently I probably skipped balancing to every other charge since I do fly just about every weekend. Could this really make a difference ? My amperage draw on the big plane is usually around 4 flight total draw over 800 mah. This is what caused me to add another pack as like you said I was getting close to 1/2 my total capacity.

    This has been an eye opener.

    Thanks

    Johnny Snead

    I ran out of Altitude, Airspeed and Ideas !

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    RE: Uneven Batt voltage draw

    Hi Johnny,
    About the only charger that Fromeco found that balanced the A123s well were the FMA chargers. All the other chargers did not have a strong enough balancing circuit to get the cells balanced before the charger shut off. Fromeco told me that once the A123s get out of balance they just keep diverging badly.
    Robert Ritchey
    Owner, Smart-Fly
    www.Smart-Fly.com

  5. #5

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    RE: Uneven Batt voltage draw

    I Have the same problem, I am using The Compatition 12. The last two charges one battery draw 980 Mhs and the other was 2030 Mhs.(4 Flights of 12 minutes and 10 Hitec HS-7950TH Servos)
    I have never Balanced my batteries A123 racing.
    The second time that I charged had almos the same amount on each battery.

  6. #6

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    RE: Uneven Batt voltage draw

    Hi,
    This is the problem with A123s, they are very hard to get even battery draw, especially when you do not balance them with a charger that does a good job of balancing.
    Robert Ritchey
    Owner, Smart-Fly
    www.Smart-Fly.com

  7. #7

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    RE: Uneven Batt voltage draw

    Thank You Robert, but I never had that much diference.
    So, is that If don't Balance the Batteries?

  8. #8

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    RE: Uneven Batt voltage draw

    Hi,
    I honestly do not know. The BatShare in the Comp 12 is just some high-current, low voltage drop diodes. Basically it works or doesn't. Have you checked your Deans connectors on your batteries? Are these real Deans females on the batteries? We track a lot of problems down to the battery connectors.
    Robert Ritchey
    Owner, Smart-Fly
    www.Smart-Fly.com

  9. #9

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    RE: Uneven Batt voltage draw

    I don't know about the deams female. My batteries are A123 Racing, but what I am going to do is, this weekend I will use my Fromeco batteries, to see what hapen. I let you know next monday.
    Thank you Robert.

  10. #10
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    RE: Uneven Batt voltage draw

    All,
    I found that Robert was right my charger just wasnt balancing as good as I thought it was. Once I did a few nominal discharges and brought the packs back up to full and then flew my routine, the batteries were more in line with what I wanted to see. Not perfectly matched in MAH drawn ( I never expected them to be perfect) but close enough for me ( 50mah) so I'm a happy camper and trust my A123 and smart fly set up totaly now.

    Thanks Robert

    Johnny Snead
    Webmaster NDRCC
    I ran out of Altitude, Airspeed and Ideas !


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