2cell A123 or 5cell Nimh or 2cell Lipo with UBEC for Rx pack? - RC Groups
View Poll Results: 2cell A123 or 5cell Nimh or 2cell Lipo with UBEC for Rx pack?
5cell Nimh 0 0%
2cell Lipo with UBEC 4 18.18%
2cell A123 18 81.82%
Voters: 22. You may not vote on this poll

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Aug 17, 2009, 12:44 AM
Distributed Manufacturing
Quixksilver's Avatar

2cell A123 or 5cell Nimh or 2cell Lipo with UBEC for Rx pack?

Well I really need to think hard about this subject and I need your help. I may have had a brown out in my Rx and that may have been what cause a very bad crash. If that was the case then I need to look into a better solution for powering my 7 high torque servos.
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Aug 17, 2009, 01:59 AM
Registered User
2SA123 most times the 1100s are enough
Aug 17, 2009, 05:58 AM
Registered User
Definitely A123 2S 2300 with no regulator (and ideally no switch) will be the safest, strongest and most reliable solution. The pack will hold over 5V at 70A load so even if a servo stalls you will retain Rx operation and control. You get superior performance, vastly longer shelf life, much faster recharge and lighter weight than NiMH and simpler, more reliable and more electrically robust operation than LiPo+regulator.
Aug 17, 2009, 08:09 AM
jackerbes's Avatar
The 2S A123 would get my vote for toughness and reliability. And quick charges in the field too.

If you want 6-7V nominal, a pair of 1100 mAh A123's at 80 grams (40 grams each) would work better than the 2300 mAh cells. The two 2300's would weigh 140 grams.

There are also some 17340 (17mm O.D. by 34mm long) 350 mAh LiFePO4 cells on eBay now. Those could be used in a 2S2P for a 700 mAh pack that would be about 70 grams. And various other configurations would give you other voltage choices in packs that are a little smaller and lighter.

Aug 17, 2009, 09:01 AM
Southern Pride
everydayflyer's Avatar
Sing it over and over and over again, Frosty Morn.

Aug 17, 2009, 10:35 AM
Registered User
I have used all the above combinations.

I would not recommend the 1100's A123.

In my 35% Extra, I run 2 2S A123's without a regulator, 1 rx, 2 switches.

In my Showtime 90 e-conversion, I run a 2S2P 4400 li-ion pack with the CC BEC. CC just released a higher amperage BEC recently too.

What I do not like about the A123's as a rx pack is that you cannot use a loaded ESV to watch the voltage, you need to watch how many MAH have been used. What I do like is the fast recharging. On my 4400 Li-ion pack, I can get over 12 full flights before a recharge and it charges in an hour. The A123's recharge in under 20 minutes since you never use anywhere near the full capacity as a RX pack, assuming you have a charger that can do it.

Honestly, pros and cons to all of the above.

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