On Mon, 30 May 2011 11:35:45 -0700, (Dave Platt)
wrote:

Argh. I haven't been paying attention.
Duracell 2650 2650 ma-hr
Energizer e2 2500 ma-hr
Maha Powerex AA 2700 ma-hr
Maybe I'll do some shopping and testing (timer permitting).

There seems to be a real tradeoff. In general, the very-high-
capacity NiMH cells seem to have a more rapid rate of self-discharge;
they're good for "use immediately after charge" applications, but not
so good for "charge and store" standby uses.

The low-self-discharge cells (e.g. Sanyo Eneloop, PowerEx Imedion, and
similar) seem to run around 10% lower in rated capacity.

Sanyo Eneloop.
http://www.eneloop.info/home/performance-details/capacity.html
http://www.costco.com/Browse/Product.aspx?Prodid=11504514
http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf
http://www.rcgroups.com/forums/showthread.php?t=630534

LSD doesn't have lower capacity. It's roughly the same as other NiMH.
LSD NiMH batteries have a higher terminal voltage. The energy
capacity is the area under the discharge curve, which is close to
identical for types with the same chemistry. However, the higher
terminal voltage will cause the curve to drop earlier for the LSD
NiMH, so they appear to not last as long.

Lots of vendors of LSD batteries:
http://en.wikipedia.org/wiki/Low_self-discharge_NiMH_battery

I've read that this is due to difference the structure/alloy of the
metal hydride used for the electrodes... varities which can bind more
hydrogen, also tend to suffer from more spontaneous de-binding and
leakage (or so my crude understanding goes... I probably have the
details wrong).

Dunno. I've read some on battery chemistry, but have generally
ignored NiMH as a marginal idea. Sorry(tm).

I've had reasonably good results with the Imedion and Eleloop types
for my radio go-kit... I can charge them up after use, and depend on
finding plenty of power available even six months later. Never could
do that with standard NiMH types, when I tried a few years ago... I
couldn't trust them to be useful even 3 months after charging.

Are you running an electric airplane, using the battery pack to run a
glow plug, igniting a squib, or running telemetry electronics? All
would benefit from a switch to Li-Ion.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558