T o d d P a t t i s t wrote:
David Kinsell wrote:


A better way of avoiding the problem is just having one battery.
If you have room for two inadequate batteries, then you certainly
could carry one battery big enough to last the whole flight.


1) The glider has 3 built in locations for the standard 12v
7-8AH battery. It's not designed to take larger batteries.
They are large enough for 90% of my flights if fully
charged.

Fine. Wire them together and form one larger battery in the
glider. That way you don't have to keep monitoring one battery,
trying to switch before having problems with the FR. And you
avoid the silly solution of a monster electrolytic.

Those caps are cardboard cylinders filled with caustic liquid,
and a pressure vent to hopefully avoid a rupture. Of all the
components used in modern electronics, they have absolutely the
worst reliability of anything. Putting one in a panel, for
no good reason, is not a good idea.



2) I prefer the redundancy of two batteries. I've posted
recently as to why. I know you disagree, but if you'd
camped at a glider field, without easy access to
electricity, as many times as I, you might prefer the dual
solution too.

You're missing the point. If you can carry multiple inadequate
batteries, you can certainly carry one adequate battery. Switching
between multiple batteries in no way extends the life, it just
opens the door to failures based on funny hardware, or letting
the voltage drop too low before switching.




If
you're not switching, then there's no problem and you don't have
to use all the funny hardware that gets thrown into systems trying
to fix the problem.


A switch and a cap is "funny hardware"? It's about as
simple as it gets.

Much simpler to avoid the switching in the first place, and
forget about the cap trying to hold up the system voltage
as you're doing the switch.







More importantly, it avoids the need to keep
guessing when the first battery is getting weak, and trying to flip
the switch before the FR resets.


I've never had an FR reset due to low battery. The first
sign is always the radio.





It's sad but somehow amusing that SLA batteries adequate to solve
the problem have been readily available for well over 20 years, but
people seem to keep struggling with it. I fly with a Cambridge 20,
which like most recorders in the field today can't tolerate a power
loss for more than a tiny fraction of a second. But I've never
had a single problem with multiple logs being created. Turn on
the master switch, go fly, and it just works. A 5 A-H battery can
power a normal panel for 6 hours no problem at all. Helps if
you get the voltage right, but that's another discussion . . .


Dave



T o d d P a t t i s t - "WH" Ventus C
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T o d d P a t t i s t - "WH" Ventus C
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