Dodgy Balance Lead

[Tom CB]

Hello all,

One of my 3300 mAh LiPos has just finished it';s storage charge and I went to double check the voltage with a little voltage meter you plug into the balance lead but it didn';t come on. My other LiPo works fine so does this mean I have a dodgy balance lead already?

Thanks 

[AlanN]

You didn';t say how many cells, but if you used a normal voltage meter you could figure out which wire is at fault.

if you consider the black wire as the -ve of cell 1 and the next wire as the +ve of cell 1 then check that voltage. should be between 3.0V and 4.2V
if you keep the -ve lead on the black and move meter +ve probe to the next wire you should get the sum of cells 1 & 2 and so on...

You can also consider the 2nd wire which is the +ve of cell #1 to also be the -ve of cell #2, so by moving both meter probes together 1 position at a time you get the individual cell voltages.

I';m not sure the condition which stops these little balance lead voltage monitors from showing anything

If that';s not clear I could paste a diagram

[kilby]

If you have lost the ground lead you won';t get a lot of readings

[Tom CB]

I just don';t understand why the little monitor is refusing to show anything on one battery but is fine on the other. They should be in the same state (storage) so this just doesn';t make sense :-(

[AlanN]

If you have lost the ground lead you won';t get a lot of readings

Thats probably true, if the device considers the black ground lead a common -ve and subtracts the voltage of cell #1 when it displays cell #2 etc etc.
It mights also use the voltage from the first cell to power itself, so could equally be the 2nd wire which stops it showing anything.

Bottom line is to know for certain you need to meter it properly....

Once you figure out which wire, you can eliminate a bad crimp from the equation by using a fine needle to pierce the wire before the crimp and try the meter from that point.

Of course chances are the wire is gonna have broken off inside the lipo pack    but you never know

[AlanN]

I just don';t understand why the little monitor is refusing to show anything on one battery but is fine on the other. They should be in the same state (storage) so this just doesn';t make sense :-(

Probability is one of your wires in the lipos';s  balance lead is broken/detached

I just saw your other post..... pretty obvious whats wrong then