Turnigy Low Self-Discharge (LSD) NiMH AA's

[BrianG]

A couple weeks ago, I picked up 5 of the Turnigy low self-discharge 2200mAh AA cells from my LHS. I really couldn't come up with an ideal LVC solution to use lipo in my DX3r radio, and didn't want to deal with balancing a lipo inside a radio anyway, so I figured I'd give these LSD AA cells a try.

Fresh out of the package, they read ~1.25v each. I used them for about 3 hours total and the total voltage fell only 0.1v over that whole time, which included actual runtime and storage. Normally, after a couple weeks, regular NiMHs would drop down around 0.5v just sitting on my shelf, let alone actually using them.

So, tonight, I decided to discharge them all the way and recharge them to see how much charge they take. Discharging took 470mAh out of the cells before they hit 0.9v/cell on my discharger at 0.5A. From previous experimenting, the DX3r pulls 127mA, so if I ran for 3 hours plus the amount taken out via the discharger, means they came out of the package at ~40% charge. A full charge at 0.3A (3mv delta peak) brought them up to 1.46v/cell, taking a total charge of 2323mAh.

I felt that 5 cells at 1.46v/cell is a tad high (7.3v total) to use in the DX3r, so I bled 100mAh out of them, which brought the voltage down to 6.9v (1.38v/cell), which is what my regular NiMHs came out of the charger at. Instead of doing this rather tedious charge-and-bleed process to keep them at a decent voltage, I think I'm going to go back to using 4 AA cells in the DX3r again. These cells hold more than their rated 1.2v/cell until near the end of their cycle, so I'll set the radio voltage alarm for 4.7v.

In short, these cells do what they say; they exhibit VERY little self-discharge, and charge up to more than their rated capacity. For people not wanting to deal with lipo in their radios, yet still want a fairly flat discharge curve and low self-discharge, these cells fit the bill nicely. Only time will tell about their longevity, but their cost is comparable to regular NiMh AAs, so even if they do have a short cycle life (no data to support this anywhere I've seen), it's no big loss.