What’s That Clicking Noise? Repairing a damaged JST Balance Plug

One of the resent lessons I learned with my Vendetta was to make sure that the JST balance plug on my battery is secured to the battery itself.

How did I learn this little lesson?  Oh simple…

When I was doing a bit of flying, the I had a hard “landing.” OK – I actually didn’t CRASH but the landing was more abrupt than I’d have liked.  Anyway, I guess that the plug became dislodged a bit, and when I took off again I heard a weird rattling sound.  When I got the drone back to me, I noticed the damage.

4S JST balance plug damage

Well… There’s your problem

The solution to me seemed simple enough.


First was to source the parts.  Thankfully, Amazon had a good source, that was available via Prime.  Essentially, what I had to search for was a 4S (or whatever your battery size is) JST Balance Charger Plug.  In my case it was an extension cable.  I found this INCREDIBLY useful, as not only do I have plugs, I have spare wires for another project, as well as options if the propeller chews up the wires in the future.

It’s inevitable, really.


The next step is to get the plug I need removed from the wires.  To do this, you need to know how the wires go in.  Thankfully, my damaged one showed me that answer.  The picture doesn’t show it, but on the top of the pin at the end of the wire is a small clip that is used to lock the wire in the plug.

To remove the wires from the good plug, I took a small flat head screwdriver and proceeded to mash the life out of the pin. While doing that, and firmly pulling on the wire, I was able to remove the wires and pins from the original plug.

Moving to the New Plug

This part requires a safety disclaimer first:  Unless you’re actively damaging your cell, that battery is going to have charge in it.  That means you need to take great care to avoid allowing the ends of the wires to come into contact with each other.  The best case scenario is they’ll weld together and you’ll need to cut the wires and solder in new connectors.  Sparks, fires, and explosions are not out of the realm of possibility.

The other important thing to remember is you need to plug the wires up in the same order they came.  If you’re lucky, your plug already is in different colors.  If you’re not, well hopefully you’ve only had one wire pop out.

The first step here was to plug in the wire that was loose.  Easy enough as it was out.  A firm push and the wire connected in.

As for the remaining wires, I wanted their clips to be in solid condition, so instead of using the screw driver trick from before, I got a solid pair of wire snips and carefully cut the plastic around the wire, and used a small flat head screwdriver to pry the plastic apart to carefully slide the wire out.  As each wire was freed, it then went into its port on my plug.

All total, the work took maybe about a half hour and $5 of materials to save a $30 battery.  Good savings, I’d say.

Broken & Reparied Plug


While I was 100% confident in my work, the first thing I did was test to see if the wires were working at all.  I plugged up my battery tester and, certainly enough it was reading all four cells.

After that, the battery went on the charger and when I went to retrieve it when it was done, I was greeted with a full battery and a yard full of snow.

Oh well… you win some, you lose some.  But the long and short of it is thankfully a destroyed JST plug like that can be fairly easily & safely repaired.

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Posted in QuadCoptors, Repairs

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Quick About
A complete novice to electronics, drones, and pretty much all things RC with OCD has thrown himself head long into FPV freestyle and racing!

Currently crashing:
Custom Built Airblade Eclair V2 Lite
Custom Built Tiny Whoop on Acrowhoop V2 board.
Custom Built Tiny Whoop on Furibee F3 board
Custom Built Beebrain v1.2
Emax Babyhawk on a Carbonfiber Frame
TBS Vendetta V1

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