Nov 26, 2006, 07:06 PM
Joined Mar 2004
Charging A123 cells with PULSAR 2.07
I got to the point this weekend to have a chance to spend some time with the new A123cells and Pulsar 2. I got the balancer for larger packs on the way, but I was curious how these cells behave as a single cell or in pairs.
1. I have checked all 8 new cells for voltage
They all were in 3.311-3.313V level out of the factory - suprisingly tight.
2 Next step was to cycle a couple of them.
The charging went smooth, but the discharge rate of one cell was limited for some reason. I redid the wires and discovered that Pulsar is rather optimized for higher voltage packs; and with two cells, process went by smooth with all numbers between 6A and 10A. No signs of heat. The highest temperature on cells was 26.7C (see graphs)
The bumps on the temp graph were due to touching the sensor or forgetting to put it on cell can
Fan on Pulsar went "on" once.
3. I was worrying about how to balance the freshly charged pairs and found that PULSAR's TEST program has a precise Voltimeter and you can zap the cell with any value of amps for 5 seconds and observe how Voltage on a particular cell fluctuates and compare it with another cell. BINGO. By adjusting Amps volume, I was able to detect 0.003 -0.005V differences between cells. 15 minutes later I have checked it again and one zap with 200mA for 5sec made them perfectly even for some time.
I will check it again later tonight.
But at this point, do I need balancer?
Probably for larger packs, yes.
4. PULSAR has two ways to charge A123 packs
FAST, where the topping voltage is 3.65V, but you can go lower to the 3.45V with 10mA discretion. SOFT, start and 2-3 steps down of soft finish is applied
NORMAL, with 3.6V tip off and gradual lowering the Amps value all way down to 200mA. This seems like a winner against overheating and more capacity pushed in. Average about 200mAh more compared to FAST charging, but this is still under investigation.
5 Discharging is set to 2.8V with soft start and soft finish (Pictures)
Pulsar is great as usual, but these A123 cells are over my head. Rock solid in every measure ( I need to find the way to energize the MPX Tx (6.6V versus 7.2V) with it - other application are straight forward)
More to come
Last edited by Smyk; Nov 27, 2006 at 10:10 AM.