On 4/25/2013 11:56 AM, Don Johnstone wrote:
Please never connect batteries parallel, it's just asking for trouble.

Absolutely, if you are not convinced ask yourself why aircraft
manufacturers go to the added expense of designing and fitting expensive
and complicated fuel crossfeeds. The simple solution would be to connect
all tanks so they all feed, the problem with this approach is that if one
tank has a leak it will drain the fuel from all the other tanks. Same thing
applies to batteries.

The two tank solution solves one problem and introduces at least one
other: many pilots have mismanaged the switching between tanks, causing
big problems they would not have had with a single tank.

Losing instrument battery power isn't nearly as dangerous as running out
of fuel. My preference is to install a single battery that can easily
operate the glider for at least two very long flights; second choice is
paralleling two identical batteries to obtain that duration.

I have considered my options for a dead battery in flight. Because it is
such a rare occurrence for me - never in 35 years of soaring - I'm only
concerned with how it would affect my safety, and not convenience or
running a flight recorder (eg, during a contest or record attempt):

* Where I normally fly (Pacific NW), I'll land at an airport.
* At more challenging areas I fly at infrequently, like out of Ely, I
carry a handheld GPS, or soon, use something like the ClearNav vario
with a primary battery good for an hour or two, so I can actually find
that airport to land on.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)