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Old Feb 06, 2005, 07:22 PM
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Sabrejock's Avatar
Winnipeg, MB Canada
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NiMH vs LiPo

I fly airplanes that demand a lot of snoose, say 1000+ watts. I've been using GP3300's with a lot of success. I'm a sport flyer so I don't demand the N'th degree of thrust/weight. I'd like to know from people who use both types in my kind of scenario whether the LiPo's will stand up as well as the round cells for longevity. I'm talking abuse here not park flying. Tex.
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Old Feb 06, 2005, 08:05 PM
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Huntington Beach, CA
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How many GP3300 cells do you use in series/parallel? It is easy to get a Lipo pack to handle 1000+watts, and it would be lighter than GP3300s, but at least twice as expensive. The Lipo batts would hold a higher voltage under high amp draw.
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Old Feb 06, 2005, 08:05 PM
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Perth Westen Australia
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Quote:
Originally Posted by Sabrejock
I fly airplanes that demand a lot of snoose, say 1000+ watts. I've been using GP3300's with a lot of success. I'm a sport flyer so I don't demand the N'th degree of thrust/weight. I'd like to know from people who use both types in my kind of scenario whether the LiPo's will stand up as well as the round cells for longevity. I'm talking abuse here not park flying. Tex.
Longevity, I suspect with lipo's due to the relative newness of the technology in RC apps the jury is out on your question for a while. There is no doubt they can burn well when abused.
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Old Feb 06, 2005, 11:40 PM
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Gaithersburg, MD, USA
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Ni MH

Quote:
Originally Posted by Sabrejock
I fly airplanes that demand a lot of snoose, say 1000+ watts. I've been using GP3300's with a lot of success. I'm a sport flyer so I don't demand the N'th degree of thrust/weight. I'd like to know from people who use both types in my kind of scenario whether the LiPo's will stand up as well as the round cells for longevity. I'm talking abuse here not park flying. Tex.
Please help us establish a baseline for the Ni MH. When you demand a lot of "snoose" from your GP 3300s, how many cycles do you get or have you failed a pack? We understand car drivers abuse them mightily and accept as little as 25 cycles in competitive racing. the largest power tool manufacturer cites 150 cycles in power tools for the ubiquitous 1.2 AH Sub C Ni Cd. Our guess is that flyers would not accept less than , say 100 cycles except perhaps in all out glider competetion. RD Blakeslee and I seem to have the longest string of data and have used first gen KOK packs for about three years. My benchmark is a 3270 pack with about 150 cycles of deliberate abuse that still holds 80% capacity.
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Old Feb 07, 2005, 06:30 AM
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Europe, Austria, Burgenland
Joined Mar 2002
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compare this:


konion1100 3s1p-pack...

the green line: cycle nr. 5
the blue line: cycle nr. 75

nearly no difference..

the cells were also very nice in balance !
after 10% discharge here the voltages between the cells after 75 cycles !
4,139 - 4,143V ... very good !

i doubt, that a GP3300 after 75cycles will be that good compared to it, how it was at cycle Nr. 5

for the balancing: meanwhile he is at 150cycles.. still in balance, still running strong..

the cell were charged with 1,5C
and discharged with 11-12C
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Old Feb 07, 2005, 10:19 AM
jrb
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Edina, MN, USA
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Hi Tex,

I fly my .60 Velox with both NiMh and LiPos; my NiMh are not as good as the GP3300s, theyíre Zapped and Pasted in SPTs, the best that could be done with Panasonic 3000s. Down a little on capacity by definition, but also not as hot as the GP (Iíve got them for other planes).

From what I see performance of the 6S or 20R is virtually the same; the bit of difference in weight isnít really noticeable in my Sport Scale Aerobatic (just under1Kw).

Your question though was longevity, not flight performance. As of yet I havenít dented the longevity of either my LiPos, GP3300s, or the P3000 I use in the Velox. But, my other packs of P3000s donít seem to hold up as well as NiCds. My impression is that the GP3300s are much better.

My LiPo insider/nephew, as well as others around, here confirm that when used within their specs longevity is not an issue.

Many seem to think as long as you donít fly a WOT its OK to have thing over specíd @ WOT; I donít subscribe to this, and add cells, etc. to keep my systems within their specs @ WOT.

Hereís another point to consider, only once have I flown out (nearly) my LiPo pack in the Velox; 15minutes is a long (too) time to fly! 3300 propped in the 30s are great duration for sport flying. 1/2hour recharge is tolerable when you (I know you do) have a van full of other planes to fly.

An hour plus to refill a LiPo is not a typical day at the field task.

So, if you can do 2 to 3 Rpacks for the price of a LiPo; it still favors the R.

The 3700 are coming; but these too may have gone too far on capacity for the typical sport flight; too long a recharge.


BOL,


Jim
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Old Feb 08, 2005, 03:22 PM
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Thanks, all: I get the feeling that time will tell. At times I'm using 60A at 30v which the 3300's do with ease. I'd have to rob a bank to do this with current price of LiPo's. I've just ordered in another 100 so I'll be able to double pack most of my larger planes. And I'm trying to standardize at 24 cells to make it easier. See ya in June, Jim, if all goes well. Tex.
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Old Feb 08, 2005, 04:59 PM
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thats is doable wih 9s2p of say 2200 LIPO cells. About $300 worth.

What do 24 3300's cost? $120?
Neither sounds cheap to me.
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Old Feb 09, 2005, 09:01 PM
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Actually about $110 US vs About $480 US. And for me in Canada I take a bunch of hits from the tax man on top of that. Tex.
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Old Feb 10, 2005, 03:35 AM
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www.cheapbatterypacks.com, get 18 Irate 2200 cells and make your own pack.

Save you 180 dollars.
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