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Old May 22, 2010, 08:33 AM
Southern Pride
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Haralson County GA. USA
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Comparison graph of 2100 LSD NiMH and a 2100 (not 2.2as on legend) LiFePO4.
http://www.rcgroups.com/forums/showa...1&d=1274374944

Charles
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Old May 23, 2010, 06:23 AM
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USA
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It sure would be nice if Futaba approved the use of these or any other LiFePO4 battery packs w/o the use of a regulator/BEC.
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Old May 23, 2010, 06:58 AM
Questionable judgement
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Charles Town, WV
Joined Jan 2008
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They are just playing it safe. I am using 2 cell A123 in all of my gas planes with 7 and 14 channel fasst rx's. I will never go back.
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Old May 25, 2010, 07:06 PM
Fly'em like you Stole'em
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The Gehto,Ca.
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People have been running 6volt Nimh packs forever . If you notice a good pack is over 7volts when it is charged . I am also running a regulated 7.4volt LiIo pack in my Gasser . No problems . People at Futaba need to get off there buttts and answer some questions we have by testing there product on stuff we want to use . Who wants to use an outdated Nicad pack any more ? Why are Tx's still comming with a 700mah nicad pack when better technology is around ? My 9c Super has been a great radio but I am done with Futaba when I go 2.4 . Can you say AURORA .

Everydayflyer , I don't believe that chart . I get about 5hrs of flight on my LiFePo4 pack in my Tx before I charge it . It is usually at 9.7volts still . I could probly go another few hours on it . I don't think I have ever got anywhere close to that on a Nimh pack of a higher mah .
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Old May 26, 2010, 04:25 PM
More Motors, More Fun... :-)
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Phoenix, AZ
Joined Jan 2008
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Quote:
Originally Posted by MikeMcChiken View Post
People have been running 6volt Nimh packs forever . If you notice a good pack is over 7volts when it is charged . I am also running a regulated 7.4volt LiIo pack in my Gasser . No problems . People at Futaba need to get off there butts and answer some questions we have by testing there product on stuff we want to use . Who wants to use an outdated Nicad pack any more ? Why are Tx's still comming with a 700mah nicad pack when better technology is around ? My 9c Super has been a great radio but I am done with Futaba when I go 2.4 . Can you say AURORA....
I don't think We should quite ditch Futaba yet . True, NiCd packs are ridiculous, but clear answers to the LiFe question would be appreciated (ya know -- it's only a few tenths of a volt -- NiMH vs LiFePO4).

I think possibly that the voltage discharge "shelf" of the LiFePO4 battery may have something to do with Futaba's position. (Mike, pda4you, refers to this in his review at the end in the "minus" section: "Voltage dump is steep at the end of useful capacity".

This in my mind would be a legitimate concern. This would make inexpensive low-voltage detection tricky. But with careful battery management, the LiFePO4 advantages seem to outweigh the disadvantages, especially considering the disadvantages of other battery types.

An official reply by Futaba would be very appreciated.
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Old May 26, 2010, 04:33 PM
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I got a response from Hyperion when I got the Tx pack . They said I could run it down to 9.0volts on there 9.9volt pack and it would still have capacity left . So I am guessing the 6.6 could go to 6.0 safely .
I would like to know how to get a good mearsurment on these . What kind of load do we test these at ? Maybe we can just read the voltage with no load like a Lipo ?
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Old May 27, 2010, 07:57 PM
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Do a discharge cycle on them with your charger. Watch, they drop quickly around 3v-2.9v/cell to the 2.5v number then tell you not to go below. I fly to 6v then recharge, there is no question I am missing capacity, but don't need to squeeze the last 100-200 mA out of a pack.

Then you can decide on your own floor limit for the cells.
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Old May 27, 2010, 08:12 PM
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The Gehto,Ca.
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Quote:
Originally Posted by pda4you View Post
Do a discharge cycle on them with your charger. Watch, they drop quickly around 3v-2.9v/cell to the 2.5v number then tell you not to go below. I fly to 6v then recharge, there is no question I am missing capacity, but don't need to squeeze the last 100-200 mA out of a pack.

Then you can decide on your own floor limit for the cells.
I thought I was missing capacity too on the Hyperion 9.9volt pack until I contacted them . At full charge it goes to 10.2-10.4 . It drops to 9.9 in a couple minutes then in about 15-20 minutes to 9.8 . But right now I have used my radio for almost 5hrs and it is hanging at 9.7 . They say in their LiFe and the G3 Lipo's get better with 20 or so cycles . I think I put about 1100mah's back in after about 5-5.5hrs of use with the voltage down around 9.6-9.7 .
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Old May 28, 2010, 09:20 AM
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so. cal.
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Maybe this is a dumb question, but I am not seeing much about chargers to use, I have lots of Lipo's, and I have Astro 109 chargers with the Astro Blinky for balancing, and have been very happy with what I have, do I need to get a more compatable charger if I start using the Life batteries as receiver packs?
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Old May 28, 2010, 09:23 PM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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Simple answer yes unless you monitor the charge and stop it when 3.65- 3.8 per cell is reached.

My now very old A123 charging thread

http://www.rcgroups.com/forums/showthread.php?t=603368

back then few chargers had a LiFePO4 mode.

For a 2S receiver battery the Pb (lead acid / gell cell) 6V mode works well.

There is a mod for the AF109 ,see post at link.

Some childrens electric cars use 6V Pb battery and a charger for one of these should work fine but charge needs to be monitored just to be safe . I use a 2S LiFePO4 2300 battery in a hand help spot light whic had a 6V Pb gell cell in it and the original charger works fine with it.


Charles
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Old May 29, 2010, 10:53 PM
LarsL
United States, IL, Naperville
Joined Sep 2006
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I have a 1/5th scale Super Cub that I am outfitting with 2 Spektrum DS821's, 4 Hitec HS-85MG's, and a Hitec HS-81. All are rated for 4 and 5 cell NiCd/NiMH. Am I OK with using one of these new Hobbico LiFe batteries to power the airborne systems?

Lars
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Old May 31, 2010, 09:12 PM
BadPilot
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United States, IL, Custer Park
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I just wish LiFe batts did not weigh so much. Super batteries with great benefits minus the burning risks.
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Old May 31, 2010, 10:18 PM
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The Gehto,Ca.
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They are lighter than a Nimh pack . What do you mean heavy? Any other battery is lighter than a Nimh . Lipo , LifePo4, A123
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Old Jun 01, 2010, 09:39 PM
BadPilot
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United States, IL, Custer Park
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Quote:
Originally Posted by MikeMcChiken View Post
They are lighter than a Nimh pack . What do you mean heavy? Any other battery is lighter than a Nimh . Lipo , LifePo4, A123
I was referring that LIfe batts are heavier than a Lipo and that was the only negative item about that type of batt. If I am using it in my transmitter, no big deal but in a flying plane it could be especially as the power source.
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Old Jun 02, 2010, 09:35 PM
OOPS
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USA, GA, Cochran
Joined Jun 2008
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I use one in my 87 shp,my 70 slick,and 65 vyper for rx packs.charge once fly all day.only have to swap the motor packs out for recharge
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