My 2100mah Art tech 3s LiPo battery gives me an "LOW VOLTAGE" error on my charger, I have a multiplex charger that can charge, discharge,cycle almost all battery types.

Ive set it to 2100mah and 11.1v(for 3s) charging.

Any idea as to how to solve the low voltage of the battery? Its brand new. had 2 flights on and was in a box for 2 months

the cells are probably below 2.75v per cell, or 8.25v for the pack. If the pack is lower than that, then it really isn't safe to charge it. Double check it with a multimeter and see what you get. You could also measure each cell, because maybe only one of them is bad or something.

It sounds like the voltage has dropped to low for the charger to recognize the pack and be able to charge it normally. You can recover packs that drop in voltage, but you need a charger that somewhat acts like a dumb charger and just charges the pack in the first phases no matter what the condition of the pack is. Then you set the charge rate to 10% of the typical 1C rate. So on the 2100 pack, somehwere around 0.20 volts. Closely monitor the pack while charging. If it gets above the 3.0volts per cell and continues charging, you may have recovered the cells.

Thanks , will try that