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Old April 13th 20, 05:41 PM posted to rec.aviation.soaring
2G
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Default Battery switching without tears

On Monday, April 13, 2020 at 3:45:04 AM UTC-7, Tim Newport-Peace wrote:
At 03:55 13 April 2020, 2G wrote:
snip

Well, today I did measure the inrush current: the peak current was 9A,
very=
close to what I had simulated with Spice. This current is very brief and
t=
otally within the capability of the switch to handle, but a few ohms of
ser=
ies resistance will cut it down to a couple of amps if you are anal about
i=
t.

Tom

A while ago, I asked if anyone else has experienced your problem.
Apparently not.
The LX9000 has (presumably) a capacitance of its own which sustains it over
changing batteries in most cases.
If there is a high load from other devices on the Bus then there may not be
sufficient capacitance in the LX9000 and it need some help.

If we isolate the LX9000 from the other devices on the Bus with a schottky
diode, then other devices on the Bus will not drain the LX9000’s
capacitance during switch-over as the diode will be back-biased. If it
still needs some help, a small capacitance can be added on the LX9000 side
of the diode.
This will also lead to a reduced inrush current as the connected
capacitance will be less.


Hell of a lot easier just to add a capacitor to the bus line, and it can be significantly smaller than the 39000μ that I used (10000μ would probably be fine).