[NRVR-Members] Rocket PSA: Problems with 110/220 Rotary Switches & LiPo Probs with "Protection PCBs"

[Bob Schoner]

Wow hadn't heard either of those before. Thanks for passing that on. I know
it isn't elegant but I still am a fan of the simple "twist and tuck"
method. I prefer to leave the wires sticking out and tape them to the
outside of the body tube.

I guess unless you buy some military or aerospace grade of switches there
is probably a chance of failure. I have several rockets with those
switches. I would suspect they are more like Kelly to fail after a hard
landing or some other traumatic event. Not really sure if I will replace
them or take my chances

Thanks

Bob
On Mon, Mar 13, 2017 at 7:43 PM Thomas Tweeks Weeks <tom at theweeks.org>
wrote:

> Hey all.. esp you L3 guys.
>
> So I'm designing my ebay for my L3, and I just got the brand new
> PerfectFlight StrataLoggerCF in the mail (the new one with the speaker/LED
> connector).. and there's a little warning handout about common critical
> failure modes they're seeing back from their customers.
>
> Failing 110/220 Power Switches:
> There is new StrataLoggerCF power check feature & very surprising warning
> about using 110/220 AC style switches of this type:
>
> https://www.apogeerockets.com/Electronics-Payloads/Electronics-Accessories/Electronics-Rotary-Switch
>
> I know these are very popular arming switch styles and have been for at
> least a 15-20 years or so (I have a couple in my own parts bin), but check
> out what this leaflet from Perfect Flight is saying about them now:
>
> "We have had numerous reports of failures of the 110/220 rotary switch
> that is sometimes used [...] in rocketry applications. The failures
> typically in one of two ways, either as:
> *  a switch that turns off when tapped or wiggled, or
> * a switch that exhibits a high resistance (several hundred ohms) when
> turned on
>
> [Our new WiringCheck] feature [... which performs a pre-flight
> load/no-load comparative battery test] is intended to reveal the latter
> type of problem, but we still do not recommend the use of this type of
> switch in rocketry applications. [...]"
>
> So in short.. I don't know if this is a NEW issue (e.g. from cheap Chinese
> supply of rotary switches), or an old time gremlin that is just now being
> revealed. Either way, since this info was nowhere on the PerfectFlight
> website or on line documentation (it was thrown in as a warning card in my
> latest purchase), I hope after this is archived in our mail list that it
> will serve as a warning to others. (someone might want to re-post it to
> RocketryForum.com, et al).
>
> Warning About Some LiPos:
> This little info card is useful, and also contains a warning about using
> LiPo cells with over-current protection circuitry shink-wrapped into them,
> as the short condition of some ematches will shut down such batteries..
> causing another type of critical power failure to a critical recovery
> component of your rockets.
>
> Just wanted to share.
>
> Tweeks
>
>
>
>
>
>
>
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