LiPo battery balance connector often get damaged by spinning propellers and I will show you how to fix it. It’s extremely dangerous to use LiPo with a broken balance connector as it can short itself easily and cause fire.
Table of Contents
What’s Balance Lead For?
The balance connector allows voltage checking of each cell in a LiPo battery and safe balance charging. For more info about LiPo battery, check out my tutorial.
Here are examples of a 4S and a 2S LiPo batteries, how the balance lead is connected to each cell.
What to Do with Damaged Balance Lead?
If you have a damaged balance connector, you should first check the voltages of all the cells and make sure they are within safe range. A broken balance connector could get shorted and over-discharged. In which case you should decide whether you want to fix it, or just dispose it.
Here is how to dispose a LiPo battery safely.
If there is no sign of physical damage to the rest of the pack, and all the cells are fine, you can then proceed to fix or replace the broken balance connector.
Buy New Balance Connectors
If you’ve ever retired old LiPo, you should keep their balance leads and they are handy replacements. But if you don’t you can just buy some brand new ones:
- Banggood: http://bit.ly/2NOtWwi
- Amazon: https://amzn.to/2AlClFK
- GetFPV (4S): http://bit.ly/2K01jtT
How to Replace Damaged Balance Plug
All you need to do is to start with the lowest wire (ground – usually black), cut it, strip it, and insulate with some electrical tape. Work your way up to the highest wire. DO NOT cut more than one wire at a time!
Solder the wires to the new balance connector ONE WIRE at a time, and put heatshrink on before moving to the next wire to prevent electrical shorts.
If you ever get confused about which wire/cell you are working on, just check with a multimeter. Put the multimeter on DC Volts, put one probe at the black wire (negative) in the XT60 discharge lead, and the other probe at the wire you are working on. Each wire in the balance lead will give you a different voltage reading.
Balance Connector Protector
These “LiPo balance connector savers” provides some protection to your balance plug, but they are not indestructible just so you know.
- Banggood: http://bit.ly/2LWwQPf
- Amazon: https://amzn.to/2uYJl6f
The exposed bit can still get damaged in some situations, but certainly better than without it.
Edit History
- Apr 2015 – Article Created
- Sep 2018 – Updated
18 comments
Best diagram I’ve found for balance leads, figured out from this how to do single wire balance for my drone pack I’m building. My pack I’m using has the 3 wire balance connector, drone only has 1 wire. Testing out tomorrow. How all goes well!
Hi there i have a 6s battery with the balance plug damaged and i have acquired a new balance plug that didn’t come with any wires at all so i can’t splice them as you described above, is there some way save destruction and a bomb shelter to remove the wires with the metal key bit still attached from the old plug? i could cut them but im sure they’ll just fall out of the new plug. Thank you much for all your help both past and present, have yourself a good day
Providing that the metal key bits in the old plug are still perfectly functional (usually it’s not the case when you damage the balance connector, they become deformed and unsafe to be reused), you can remove them and insert them into the new empty plug in the exact same order. To remove them, just press down on the exposed surface towards the plastic part – it’s hard to describe, search on youtube for videos how to remove wires from JST XH connectors 2.54.
I think the easist solution is to get a balance lead that comes with wires (doesn’t cost much), and just cut the old one off and solder the new cable to the battery, so you don’t need to mess with the old metal key bits at all.
Hey Oscar thanks for another very informative article, I have a question about the name of the other popular connector, if the balance lead are JST-XH, what’s the name of the connector used on things like the 3 wire fpv camera, the gps, and also I’ve seen them on the VTX. They look similar but are smaller than the balance lead connectors. Thanks.
Here’re some charts of common connectors used in FPV: https://intofpv.com/t-tiny-jst-connectors-diagrams
So if the balance lead gets completely destroyed are you going to dismantle your battery to figure out which lead goes to which cell?
Nah, if the wires are still soldered to the battery, just cut the wires and solder a good one on. But if the wires are too short, or the break happens in the solder joins, then yea you’d have to remove the wrapping and re-solder the wires.
Is the order important?
Yes, because the cells are connected in series.
Is the red wire connected to the first or last cell??
In your illustration, it is to the first, but most other do it opposite
Regardless of color, pin 1 on the left with connector facing up is usually common ground
If its not beat up too bad you can just depin it and put the pins in a new plug. It looks like it was never beoken.
3D Print a balance plug clip – http://www.thingiverse.com/thing:1511493
Hi Oscar,
The best thing is offcourse to make sure it never happens again.. I bought some beepers that plugs in the balance plug. I hot glued the beeper to my frame and when I am flying I plug the balance plug in it. Looks super neat and only adds a few gram.
sorry what’s the beeper for? isn’t it going to make a lot of noise when you fly?
Hi Oscar,
I think he means a battery cell checker. All its there to do is hold the balance lead away from props
Yeah, make sure you don’t cut more than one wire at a time, made that mistake once with scissors and shocked the hell out of myself and killed the battery
Oh yea! ＯＮＬＹ ＯＮＥ ＷＩＲＥ ＡＴ Ａ ＴＩＭＥ！