I have noticed when charging my lipo batteries, every 3-4 charges when he charge is about complete my charger (assesnd) beeps and says "volt err". if i hit back and charge it again the charge goes a few seconds then says "charge complete and the volt meter shows about 4.20 per cell. I have looked in my charger manual and have not found anything, any ideas ? Thanks

Could be a loose connection. Loose positive wire, loose negative wire, loose balance wire, Any loose connections/plugs between the battery and the charger. Bad balance port on the charger or the battery. Bad battery, weak cell or something wrong with the charger. Do you have more than one charger, more than 1 battery or more than one charging cable to eliminate what the problem might be?

Agree with post above. Swap items to eliminate which piece is the problem. Mine ended up being one of my 4mm bullets > Deans male cables. One of the extra thin metal pieces that helps keep the connection snug came off. I ended up bending the thicker metal piece to compensate and that error went away. I also put together an extra cable for backup. Just hope it doesn't end up being the charger itself.

I had the same issue replaced the charging leads and good to go.