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Toggle switch for small aircraft charging system in case of failure
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richard.cs:

--- Quote from: ITman496 on April 16, 2020, 11:00:50 pm ---A question, can I parallel them or is that a bad idea?  I figure if I get one like you listed, putting two in wouldn't hurt?

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Yes, you can parallel them but they won't really share the dissipation very well and you should assume one (random which but probably the same each time) will absorb all of the energy. If you want multiples as a backup and each can individually cope with the expected energy then this is fine. If instead you want to increase the energy absorption ability it's better to make a series string of lower voltage ones.

As a side-note the usual failure mode for semiconductors at low to moderate overloads is short-circuit. They overheat and re-diffuse into a single conductive lump of silicon. As very high currents bond wires can blow open like fuses, but that wouldn't be expected on TVS diodes which are made for huge peak currents and certainly not in your application.
ITman496:
Fascinating!  I really had no idea about the mechanical aspect of a silicon meltdown but it makes a lot of sense the way you explained it.

I will put two in parallel just for the sake of it since they are small, and I got a 5 pack.

Do you think this setup is testable or will it damage the regulator to short it out like this?  I suppose it probably won't because, well..  Looking at the schematic I found before, it uses the SCRs to short the stator winding through the bridge rectifier anyway.  So they should be used to this treatment.
richard.cs:
It should do no harm to test it, from the stator's perspective it's the same as normal regulation, and the rectifiers will see only a modest current.

You're doing the project I've wanted to do for a long time, but the rules here are very different which makes it much more difficult, plus there's the question of space. Got any photos?
ITman496:

--- Quote from: richard.cs on April 17, 2020, 08:59:24 am ---It should do no harm to test it, from the stator's perspective it's the same as normal regulation, and the rectifiers will see only a modest current.

You're doing the project I've wanted to do for a long time, but the rules here are very different which makes it much more difficult, plus there's the question of space. Got any photos?

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Sure do!  Keep in mind its a little rough still because I inherited the built from someone else and am going over it.  The fabric will be coming off next week and replaced and repainted with new stuff.  Also, these photos are in no particular chronological order, covering the span of 2 years. Hence the different looking engine, different instrument panel, windshield, no windshield.. etc.  The First picture is the most current.


Ignore the electronics in the food container.  That's just temporary engine datalogging for testing stuff while I continue to build the actual electronics.


Keep in mind that I did not have the ailerons/flaps installed for the photo because they were still strapped to a trailer at the time  ;D

 








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fcb:
I would just have a warning alarm that monitors the battery for prolonged over and under voltage, if the warning goes off I'd land and investigate/disconnect the alternator belt/wiring - I guess you fly with a small tool-pouch!
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