[NSRCA-discussion] Kavan starter with Li-Po battery

[Ken Velez]

I have a question about all this. I see people using 2S 7.4 @ 8.4V charged  and a 4S @ 16.8 V charged. I'm using a 1950 mAh 3S Extreme V2 on mine and although I'm flying Pattern electric mostly I still have other glow set ups including a YS 1.60 and my starter has no issues starting any of this and while using the 3S doesn't give you any advantage as power increase compeered to the 14.4 Ni-Cad packs available the Li-Po's hold a higher voltage under load without stressing the motor and components. Just my thoughts.

Ken
  ----- Original Message ----- 
  From: Robert Richards 
  To: General pattern discussion 
  Sent: Friday, August 22, 2008 11:31 AM
  Subject: Re: [NSRCA-discussion] Kavan starter with Li-Po battery


  Fully charged 4S lipo will be over 16v. Has anyone tried a 4S A123 pack? That would be 14v or less.

  Bob R.


  JShulman <jshulman at cfl.rr.com> wrote:
    I had the same thing happen to mine with a 4S set-up. The first warning sign was the starter had gotten really hot. The second, and
    final sign, was the starter locked-up. I think it's a combination of the higher voltage and, for me, the longer time running it
    trying to start the motor (setting and fine tuning), maybe.

    Regards,
    Jason
    www.jasonshulman.com
    www.shulmanaviation.com
    www.composite-arf.com

    -----Original Message-----
    From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of
    adriancwong at earthlink.net
    Sent: Friday, August 22, 2008 3:26 AM
    To: NSRCA-discussion at lists.nsrca.org
    Subject: [NSRCA-discussion] Kavan starter with Li-Po battery


    To all,

    I have been using a Kavan starter with a 10 cell, 12V, 2.2A ni-cd pack for many years with good results. However, ever since the
    1400DZ came out, it required more cranking power from the starter and one charge would normally only last for two weekends of
    flying. By the time the 160Z came along, I've switched to a 12 cell, 14.4V, 2.2A ni-cd. Again, it performs flawlessly. However, as
    you are aware, the 12 cell pack is really heavy.

    At the beginning of this year, I have switched to two li-po packs - 2 cell, 7.4V, 2100 mAh with 15C continuous, 20C burst on each
    pack. The first starter lasted for 6 months until it stopped working after normal wear and tear. The second one stopped working -
    frozen solid - after about 2 months - I could tell this one had some strange noise to began with, like something was rubbing inside.
    Therefore, I wasn't surprise that it stopped working only after two months.

    The third starter I rigged up was relatively new, and has been working perfectly, until this afternoon. After the first flight, it
    was frozen solid again. Like the second starter, it didn't give any warning sign whatsoever - slowing down, getting hot on either
    the starter or the battery.

    My question:-

    1) Am I using the wrong battery pack?

    2) Too high of a discharge rate because it's a li-po instead of ni-cd?

    3) Once the starter is frozen, is there a way to fix it? Sure hate to keep tossing away starters.


    Any advice or suggestion from you electric gurus are greatly appreciated.

    Thanks in advance,

    Adrian


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