Re two batteries, was Miracle switch failures

[Tomanek, Wojtek]

Just FYI
 
I did use a similar two-battery system; the problem is that you have to find
a high capacity diode (I used at least 1.5 Amp or higher, which is better).
The voltage drop is 0.7 for silicon diodes, this works well with 5C
batteries.  However, using diodes introduces an additional single point of
failure but having two independent systems balances this to some degree.  
 
Now I use two batteries each with a switch and charging jack and no
isolation between the two.  The primary battery is a 5C (NiCd or NiMH) or
Li-Ion with a 5.6 Volt regulator (other will work too 5.2 - 6.0 volt).  The
backup battery is a small 4C NiCd 250 mAh.  Both switch connections plugged
straight to the receiver.  If you have to plug it through a Y with a
secondary type servo (throttle or gear).  
 
What happens in this system is that the primary battery chargers (equivalent
to trickle charge) the secondary battery and keeps it at ~ 5.3 (with the 5.6
Volt regulator).  If the primary battery fails the secondary will be enough
to land, if the secondary fails the primary will do the landing duty.  This
assumes only an open circuit failures on a switch, plug, or even battery
etc.  I generally charge both batteries, but if I do not, I notice a little
larger drain after the first flight on the primary battery (equivalent to
two flights). 
 
I always check both batteries before and after each flight that way the is
less chance of a surprise.         
 
This is not any better than other proposed systems, just what I have used
for some time.  
 
Good luck
Wojtek
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20030331/4fbf9bbf/attachment.html