A123 Cells (Think I got lucky)

[kyleservicetech]

I purchased six new A123 2300 Mah batteries from www.voltmanbatteries.com earlier this year. They went into a model with a Hacker A40-10L motor that flew very well.

Thursday, the Showtime 50 model was flown four times, and because of wind and to much talking it was time to go home. Well, another club member came to the field with family from Florida, that had never seen electrics fly.

So, the model with the Hacker A40-10L was put into the air, and put into its paces. Got way to windy, packed everything up, went home.

Two days later, looked at this model, the new 6S1P A123 pack was still plugged in. Its terminal voltage was 2.16 total Volts DC on all six cells. . Most individual cells were around 1/2 Volt DC.

Nothing to loose, put it on a regulated power supply set to 21.6 VDC with a 5 ohm 20 watt limiting resistor, and turned it on. After a few minutes, all cells climbed above 3 VDC, so took it off, and put it on the Cellpro Powerlab 8 charger, and let it go. It showed 2140 Mah when done, usual amount for these 2300 Mah cells. Next, ran a discharge curve at 4 Amps on the Western Mountain CBA unit, looks good.

Recharged it, and put it back in the model, the motor turns the same RPM.

Sure don't recommend this kind of treatment, but guess I might have gotten lucky. I'll let the pack sit for a week, and see if they self discharge.

We'll see how they hold up for future flights.

[Turner]

Can A123's be damaged if the voltage drops too low? If yes, how do power tools cope with this?

[kyleservicetech]

Originally Posted by Turner

Can A123's be damaged if the voltage drops too low? If yes, how do power tools cope with this?

Yup, they can be damaged.

Before retiring, I ordered one of those 36 Volt Dewalt battery operated drills for the shop on a special project.

Apparently the trigger electronic speed control monitors the battery voltage, because when the 10 cell A123 battery pack gets low, it shuts off the drill motor.

That drill was a real powerhouse. The job was to travel to a customer and drill 1 1/4 inch holes in a 1/8 inch thick stainless steel panel in one hundred different control panels, using a special carbide toothed hole saw. The guys did the whole project using one battery, and about 1/2 of the other.

http://www.amazon.com/DEWALT-DC900KL.../dp/B000F1H22S