"Eric Greenwell" wrote in message
...
Bill Daniels wrote:
Lithium Ion rechargeables seem to have recently seen a 50% or so price
drop.
A 4-cell, 14.8V, 8AH with charger and mounting plate can be had for
$169.99
(USD).

Can you supply a URL? While I strongly discourage people from making up
their own Li-ion battery packs for their glider due to potential safety
problems, a _production_ battery pack with it's dedicated charger would
likely alleviate most of the concerns I have about using a large Li-ion
battery in a glider. I don't worry about the little ones in my PDA, cell
phone, or camera.

I just scanned a bunch of pages from a Google search. I'll find the one
with the specifics.


These are basically long endurance laptop batteries.

What would be the advantage of this battery over the 12 volt, 7 to 9
amphour SLA for your application? Neither size nor weight seem important
in a battery of only 8 amphours, whether SLA or Li-ion. That's a Nimbus
you fly, right?

It's about a 6 pound weight savings. (1 Lb vs 7 Lbs) for 7-8 AH. That
allows the battery to be behind the panel with short wires instead of behind
the seat with long wires. Total weight savings are not that important but
the battery's effect on balance and weight of the 'non-flying' parts is.
I've been running W&B's and 6 pounds is important.

This is still too much for me given that a SLA with the same capacity is
around $25 but the downward price trend is hopeful. Someone
contemplating a
transponder, electric T&B and other juice hungry gadgets in a $100,000+
glider might see Li-Ion as a possibility now.

Unless it allows the pilot to mount significantly more capacity in the
original battery box, eliminating the need to find a place to mount more
batteries, I don't see any benefit. Saving a few pounds seems pointless
in most gliders, even a SparrowHawk.

You can get a lot more capacity for the same volume and weight.


As for safety, the motorglider guys are flying around with GASOLINE, right?
That burns too.

Bill Daniels