I am using a LiPo battery to power a model helicopter.

After my first flight with it i noticed a yellow discoloration around the seam of one of the cells. The battery isn't puffed up.

The voltages for the cells are the following:

  1. 3.844 V
  2. 3.845 V
  3. 3.825 V
  4. 3.843V

Is it still safe to charge and fly this battery?

Image of the battery

EDIT: I did charge the battery again and flew it and it worked. But i would still like to figure out what that stuff is and why it seems to be leaking out.

  • $\begingroup$ It's a little hard to tell from the photo, but the discoloration looks like it could be from light damage to the clear plastic heatshrink around the entire pack. Does your LiPo charger support monitoring the battery's internal resistance? If so, you can try charging the battery (maybe at a lower current than usual) and keeping an eye on the internal resistance figures to see if the affected cell is significantly different from the others. $\endgroup$
    – ifconfig
    Jan 20 at 23:22
  • $\begingroup$ @ifconfig Yes i noticed that too, but the discoloration is definitely on the seam of the cell. My charger sadly doesn't has this feature. As stated in my question the voltage of one cell seems to be a bit off, but my charger shows an equal voltage during charging. $\endgroup$
    – XOHOO
    Jan 23 at 16:33

1 Answer 1


I wouldn't worry about it. IME if a lipo is going to catch fire, it'll do it when you charge it - and you should always charge as if it's going to go off like a firework anyway.

If there's a problem when you're using it, you'll notice the lack of power output. If it can't supply enough power to fly, you'll throw it out anyway. Generally you get some puffing of the cells too.


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