[kyleservicetech]

Originally Posted by daddyrabbit1954

Dennis

Until you mentioned them in your post, I had never heard about A123 batteries. I did some research and from what I can tell, you are talking about using two 2300 Mah A123 cells? I found these:
http://www.dealextreme.com/p/trustfire-protected-18650-lithium-battery-2400mah-2-pack-gray-5776
Would these be suitable? Don't know for sure if these are considered as A123 cells.

I'm not certain what those cells are, that size cell is generally 1000 mah, not 2300 mah.

Take a look at one place that sells A123 receiver packs. If you're radio will handle a 5 cell nih pack, the 2 cell 2300 Mah A123 battery is a direct drop in, no regulator is required. Depending on the size of your model you might consider the 2S2P pack from this company.
http://www.radicalrc.com/category/A123-Cells-Packs-199

They are about 1/2 the weight of a "Sub C" Nih battery pack, but have far higher momentary ratings on maximum current output.

If you pick up a charger like a Cellpro 4, that will show you exactly how much milliampere hours a flight took, so you can predict how many flights are reasonable on a charge. You can charge these A123 cells as high as your charger will go. I routinely charge mine in 15-20 minutes. And discharge a 12S2P A123 pack at 75 Amperes.

These cells have a FLAT discharge curve, so regardless of info out there, a voltage check is not a good indicator of state of charge. By my actual tests, their voltage only drops by a percent or three from 80% to 20% of capacity.

But what's nice about them, their charging efficiency is near 100%, so if you pull 472 milliampere hours out of them during a few flights, recharging them will take about 472 milliampere hours. And those Cellpro Chargers with their LCD display will let you know exactly how far discharged they got.

Don't ever short one of these batteries though. I did it once, burned the copper wires right out of the insulation. Zero damage to the A123 cells.