Empty Cells on LiPo - Balance Charger or Battery Problem?

Question

I recently opened up a box of 5 year old 3S LiPos which I had in storage. When I hooked them up to my Turnigy Accucel 6 80w balance charger, they mostly measured total voltages around 11v~. However, upon connecting the balance leads, the charger is saying that all of the old batteries have only 2 out of 3 cells carrying voltage (and one was at only 1 of 3). Similarly, when I try to balance charge these batteries, I get a "cell error". It's possible the batteries are bad, but it seems weird for them all to be bad in exactly the same way.

For example, on one of the 3S batteries, voltage reported is:

0.00 6.07 3.87
0.00 0.00 0.00

This shouldn't even be possible, there's no way I have 6.07V in one cell.

I proceeded to test the voltage of these batteries directly with a multimeter (followed this guide) and I'm seeing voltages on all three cells. What's a little odd is on the one I tested, they all seem to report the exact same voltage (3.72V). Testing the main power lead directly, I get 11.16V (3.72V x 3).

It seems reasonable to assume there's something wrong with the balance charger, but I wanted a second opinion. I was able to use the balance charger to successfully charge some new 4S batteries, but I don't have any new 3S batteries handy. Is it possible I just have a problem with the circuitry for the 3S balance connection?

Answer 1

It sounds like the balance lead for the first cell isn't connected somewhere. The wire may have come off inside the charger, or it could be the balance plug, the wire, or an external parallel board (if you're using one).

I'd open up the charger and test the voltage at the back of the balance plug, and see if you can spot any broken solder joints.