[NSRCA-discussion] Mezon 90 Lite investigation

[Derek Emmett]

 FYI:  There's a nice article in the July K-Factor that covers redundant power systems.  It discusses isolating power sources, etc... 


    On Tuesday, August 20, 2019, 02:33:56 PM PDT, Peter Vogel via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:  
 
 I misread the issue on my phone.  Indeed, it is very bad (even during flight) for the BEC to get back-fed power from a backup battery, that's what diodes are for and the DSM ESC has such a diode in place.
On Tue, Aug 20, 2019 at 6:07 AM Andrew Jesky via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:

The issue I’ve found is if you leave the battery backup on it keeps power to the capacitors in the mezon so the second you plug in your 42v source there is no buffer in the esc and this will happen. You’ll see by disconnecting your main flight pack, leave the backup on and move the throttle stick. The motor will turn over just a little until all the energy is gone. 
What I’ve found is that always disconnect the backup when you unplug the main pack or have the esc arm and need to re plug in.This is critical if your doing any amperage checks. 


Andrew 
Sent from my iPhone
On Aug 20, 2019, at 6:56 AM, Daniel Underkofler via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:


Matt, I'm of the opinion that his regulator in line with the backup rx battery would protect him (essentially acting like a diode).Admittedly, I've only used smart-fly regulators in this application.Dan
On Tue, Aug 20, 2019 at 4:38 AM Matt Griffitt via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:

All of the ESC from jetti will have the same issue. You need to put a diode in line with the bec power supply and the RX. You can get away the diode if you always plug your flight pack in and arm the esc and then turn you 2s lipo pack on. As of right now the only esc that can take power in both directions is the Graupner HV line of ESC. They work great and are less money than the mezon.
https://www.graupnerusa.com.  like I said , I am not aware of any other ESC with BEC that can take voltage both directions . I hope this helps.

Matt Griffitt 
ADGaero.com
334.380.8228
On Mon, Aug 19, 2019, 10:52 PM Xavier Mouraux via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:

Hi,
I have 2 planes with that ECS. The primary has 300 flights, the backup had 100 flights since the installation of that ESC.Both planes use the BEC at 6.2V and a backup 2S lipo with a radio south regulator at 5.7V.

Getting ready for a 3rd flight on the backup yesterday, the ECS made sparks and smoke when I connected the battery. I took the ECS apart and found what I think is a FET busted.
2 observations: I accidentally left the backup battery and BEC switches ON after the 2nd flight about 10 minutes before and only noticed it after I connected the main battery. I may have touch the connectors twice in quick successions when connecting the battery.
I usually turn the backup battery ON first to check the voltage to the receiver and then the BEC.

See pictures in that album: https://photos.app.goo.gl/gaN4bqG9BCgDyUzt8
Since I have the same ECS on the other plane, I want to understand what caused it and if I did something wrong.
Abt idea what happened ?

Could it be repaired or is it done ?
Thanks you
Xavier


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Director, Fixed Wing Flight TrainingSanta Clara County Model Aircraft SkyparkAssociate Vice President, Academy of Model Aeronautics District X
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