A123 for Rx questions

[ferincr]

I'm running futaba PCM with S9252's for the cyclic and the Gy401 w/9254 on the tail.
I've been looking at the A123's from A123racing (2300mha) I don't know if anybody is familiar and/or has any bad experiences with them, they claim that can be recharged in 15 minutes.
I've been told that fully charged are 7.2v since I'm not familiar with 6v setups I'd like to know which extra gadgets do I need to run them, I know I need a step down for the tail servo, but is everything else ok running with that voltage?
I guess the voltage is pretty similar with the most commoly used LiPos, am I right here?
Does it worth to switch from NiMh? The ones I have are 4300Mah (quite heavy), but I don't know how many flights can I expect with 2300mah A123's.
Any advice????

[kgfly]

The A123 cell spec.s are here: http://www.a123systems.com/html/products/cells.html

Important items to note:
* Nominal 3.3V, fully charged 3.6V
* Tolerate 100% discharge but practical limit is <90%
* Cannot be charged on a LiPo charge cycle, you must have a charger with LiFe support.
* Can be fast charged at 10A/4C
* 70g/cell

If you only use them for Rx packs then the FMA CellPro4S charger for ~$65 will take care of them nicely, but only charge at 3A max. Otherwise an eStation BC6 will do a 2S A123 at 5A, a BC8 at 7A or an e902 at 10A.

Of course if you buy the A123racing packs and charger you will be all set for 4C charging of a 2S1P Rx pack. Their 2S packs are available as 2S1P 2300 mAh or 2S2P 4600 mAh (310g).

How many lfights do you get out of your 4300mAh NiMH ? Expect to get nor more than half as many with the A132 2300mAh pack.

I would guess though that the voltage would be a bit high and you would need a regulator, or at least a 5A series diode to drop the voltage down to the range 6.5V to 5.5V.

[DebianDog]

Buy Li-ion Batteries (Duralites) for your Helicopters and radio. Fly all day, built in regulator, one charger, come home plug all the helicopters and radio into the charger and forget about it.
http://www.duralitebatteries.com/packages_heli.html

[RC Accessory]

The 2 cell A123's work great as rx packs! I use them myself. The packs are 2300 mah. Full voltage is 7.2V but settle down to 6.6V quickly and hold there for quite some time. In my fixed wing I just plug them in, no regulator needed. On a heli, I would recommend a regulator or a step down regulator for the gyro.

If you do not have a Li-Fe compliant charger, you can get the SLK Lipo adapter for $39.95 and use a lipo charger. Not ideal but workable.

I have the 2 cell A123's in stock, as well as the SLK lipo adapter. I also import the line of e-Station chargers which support the Li-Fe cells (BC-6, BC-8, and 902 chargers).

www.rcaccessory.com

[ferincr]

Thanks for the info, I been reading those sites for a bit, but I think I'll wait a bit longer before I commit.
It seems like LiPo/LiFe is he way to go, but since I got few NiMh packs not long ago, I'll get into lithium technology little by little.
The need for a new charger since my Triton would do some LiPo's but not LiFe, plus balancer, batteries, regulator/step down, etc is a bit much at this moment to jump both feet in (again) it seems like the battery world is rolling fast forward at this moment and I would hate to commit to something that It might become "obsolete" in few more months.
Thanks again for all the info I'll keep it in mind for when my NiMh finally need replacement.
Fernando

[skyhi]

i can't see why u would want a123 cells to power a receiver even using all digital servo's stalled. to me a 8c or even 6c lipo would work just fine

[kgfly]

For A123 for Rx pack:
+ Cheaper (although not by much at the low power end)
+ Safer and more robust than lipo (no fire risk)
+ 20 minute recharge
+ 3.6V fully charged/3.3V nominal makes 2S more friendly to Rx electronics without a UBEC or regulator

Against A123 for Rx pack:
- Heavier for a given capacity
- Only 1 cell size available
- Might need a new charger if you have a pre-existing LiPo charger without LiFe support
- Have to build your own pack (or pay a premium for pre-built)