ORIGINAL: i3dm
I am a big fan of redundant A123 Rx packs also, and on the bigger jets i even add a Froemco D-CUP capacitor as added safety.
Oli, are you using twin 1100mAh A123's in big models ? whats a BnD VX pack ?
Hi Lior.
Here is the pack: B&D VPX A123 1100 mAh
http://www.amazon.com/Black-Decker-V...6136352&sr=8-2
I use this setup on the medium size
Supephoenix that is equipped with 8 JR 3421 mini digital servos.
Here is the official A123 documentation:
Nominal capacity and voltage 1.1 Ah, 3.3 V
Recommended standard charge method 1.5A to 3.6V CCCV, 45 min
Recommended fast charge current 5A to 3.6V CCCV, 15 min
Maximum continuous discharge 30A
Cycle life at 5C discharge, 100% DOD Over 1,000 cycles
Recommended charge and cut-off V at 25°C 3.6V to 2V
Recommended charge and cut-off V below
0°C
4.2V to 0.5V
Operating temperature range -30°C to +60°C
Storage temperature range -50°C to +60°C
Core cell weight ~40 grams
As you can see, the discharge curve is fairly flat, like all A123 cells. The voltage drop per element at 20 A is maximum 0,2 V at 20 A and stays linear up to 40A: 0,4 V per element at 40A or less than 1V for a pack.