Micro Motor Community

Balancer plugs considered harmful


“We” lost a FPV brushless 2S 90mm micro quad (not mine) yesterday.
Standard E-90X frame, BR1103 8kKV, 1-2S 6A ESCs, Femto etc.
It even had a proper buzzer. What happened (or what we think happened):
The battery came loose and unplugged mid flight. No FPV feed from the quad, no buzzer, no DVR footage - bad situation. Albeit the area where we think it could be is rather small, we just could not find the machine (yet).

The connector in question was a standard 2S balance plug (used in order to save some weight) and it certainly wasn’t a hard crash. If you are flying a 2S+ brushless quad, I can not often enough recommend to use something like a XT30U.

Surely there are other “find lost quad” solutions than a buzzer (we have some good threads on the topic in this forum), but adding even more additional weight is sometimes just not an option.

Recommendations to save your day:

  • XT30U on the quad side (compatible with all your XT30 batteries)
  • Buzzer & ESC/Motor beacon (set to 1 min)
  • Properly secure/mount your lipo, velcro alone is maybe not the best idea ever while rubber bands seem to work really well for lightweight 2S packs
  • DVR (in case everything else fails e.g. water landing)


I was just about to configure a build this way. Now getting flash backs of battery ejections and jst connectors coming loose on my 8.5mm. I may have to rethink! Thanks for sharing!



Sorry for your friends loss, thanks for sharing your experience. Something to think about.



Meh. A balance plug holds plenty firmly. Preventing loss of power is more a matter of proper battery retention, than it is about the strength of the connector. If the battery is already free, I think I want the connector to disconnect. Certainly this is true on my big quads where an ejected battery has significant momentum and would happily shred power leads or tear pads of boards if the XT60 didn’t disconnect first.

Proper/convenient battery rentention is a problem yet to be solved for nano quads (or for mini quads to be honest)



I agree that you possibly want your lipo to disconnect “automatically” on a larger quad in a really hard crash. But I really think differently for <100g micro quads: Finding them is much harder if you loose battery power and I’m certain that a XT30U would have done a better job in this case.

Update: We found and recovered the machine. No real damage but really hard to find - we only found it with an improvised endoscope (aka “quad on a stick”).



The DVR is for those spectacular crashes, so you can laugh about it later, after the temper tantrum😏
Also, where was the quad?



I love this one, it’s not heavy, easy unplug but stick very well, with this I can shorten the battery cable and power cable so the total weight between JST with long cable and XT30U with shorter cable length have no much difference



Hidden under a large (strange) encased cylindrical art object made of concrete. Some artist seem to have very strange ideas which in my opinion hardly qualify as art. :wink:
We wouldn’t have been able to find the quad underneath the object without faking our own endoscope to look under it.