Conclusion - Pros
* Very, Very low impedance. Voltage dropout during
load is practicaly non existent. This is sometnig we have been strugling for over 40 years using NiCd and NiMh
cells. A123 cells deliver constant voltage no matter what load of this cells is.
* 100% efficiency,
No self discharge. There is no capacity loss between the charge and discharge modes. Once the cell
is formatted and properly charged it could sustain a charge for 5 years! Well.. is hard to prove, but one of my packs
is hooked to Voltmeter for 3 months now. Taking 3mA to support its own LCD it still measures 6.43V. Pulsar charges A123 cells
up to 3.65V (peak) and discharges them to 2.8V per cell. Between these two voltage levels resides most of the cells capacity.
It translates to 2150mA (94%). The remaining 6% capacity is spread above and under these limits. Creators of A123
cells state that the above 4.2V and under 2V limits should not to be passed in order to keep these cells healthy
and long-lasting.
* Cells are not poised to get bad during the flight (discharge mode)
You migh find it interesting, but only time when cel gets bad is overvoltage (higher than 4.2Vper
cell) during the charging proces or be left out discharged under 2V. You got strong control over cell condition as long
your charger is capable to do so.
* Workable Voltage is between 6.75V - 6V. However
charger brings 2S packs to a 7.3V level at first, pack
stabilizes at the 6.75V shortly after charging is terminated. This is lower than a fully charged 5 cell CdNi
or NiMh. Voltage discharge slope is minimal (0.75V/2Ah) and remains constant until the 6V level. Below 6V
only 100mA remains in the system. This is enough to land. I found a beeper which goes on when batteries reach the
6V level. It is a cute safty device.
* Weight of these cells is about 2/3 of average CdNi
or NiMh pack of similar capacity and voltage (5 against 2 cells). This is a noticeable saving.
* Life span is declared to be 1000 cycles under nominal
circumstances. There is no prove in real life to get to this number, but one of my packs is getting 36th charge
and there is not even slight drop in capacity. There is a push to charge these cells with high current and use them to pull
70A out. In our aplication abuse of this cells is not a case.
* Charge current could be elevated to not yet considered levels. Pulsar's 12A
capability makes this process a blast. It takes about 7-9 minutes in fast mode to charge 95% of capacity back in without
much of the heat being generated. COOL! VERY COOL! In our application we will charge
our batteries at any level of discharge. I do not see any reason to discharge this cells empty. They perform very well being
charged to voltage peak detection from any level as long cells are properly balanced at the end. Use of "Blinky A123"
balancer from Astro Flight does the trick very well. A123 cells keep the balance very tightly. Use of EQUALizer from Elprog
further shortens the charging time and most of the time there is no need for post charge balancing. You done in 7 minutes
pushing back 2000mA
As of 12/22/2009 (three years later)
*A123 cells are very robust. You can overcharge them, you can under discharge
them. They are phisycally bullet proof and doing very well in vibration enviroment (tugs).
The only thing you have to avoid is to vent them. it is due to overcharge ( safety pop off) or mechanically puncture them
or short them on the body and hole shows up through the can. Cell will not show loss in capacity at first, but gradual
oxidation inside the can will put these cells to the rest. I had one case of cell being factory not sealed properly. She did
not last a month.
