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

Fri Aug 22 09:39:41 AKDT 2008

Ken,
   THAT is the secret Ken. Good batteries are capable of delivering a higher voltage under a high current loading. If the starter is designed to run on 12V you're pushing your luck with anything much over 14V. That's why things are breaking. A GOOD 3S pack should be more than adequate.

  John Pavlick

Ken Velez <kvelez at comcast.net> wrote:
          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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