Badwater Bill wrote:

That's an interesting application. The 680 is only 15 pounds and it's
small in volume, that's why I like it. I got a hold of a couple 35
Amp-hr Gel Cell batteries today from a buddy (brand new out of the box
and he just gave them to me since his application disappeared). I'm
going to make an APU out of them and use them to hook up in parallel
during my starts. That way I'll have plenty for the flying day.

My real problem here, and I haven't talked about it, is that my blades
aren't tracked properly. I've painted one tip red and one black. You
can't track them without flying the damn thing. In flight, you look
at the tips and see what blade is above the other. Then you land and
reduce AOA on the high blade, spool up again and go for another try.
It's an empirical thing until you get it dialed in. The problem with
a Walmart motorcycle battery is that I get about three starts from it
with a 30 minute charging time between each start and the battery is
toast since it deep cycles to full discharge. That battery is simply
not designed for what I need to do.

Ah, now things are clearer. Why not setup your electrical system so that you carry one gel cell battery (no
Odessey at this point) in a quick-change manner? Leave the other gel cells (how many did you get from your
friend?) on the ground on a fast charger. On each landing, swap the gel cell with the most charged one on
the ground. When you've finally got the blade tracking problem solved, go back and install the Odessy 680
as your permanent lightweight battery.

Russell Kent