you can calibrate it by measuring the mah load when discharging i believe it is 300 mah not positive bout that measurement but there is forums that have that info there are 2 pots to adjust inside But do yourself a favor sell it on ebay its just not reliable i have had 2 the 2nd one hobbico was made aware of my issue and the one they sent had the same problem get an einstein they are 99 bucks at omni models and the shipping is free get the deluxe the adapter is a must AGAIN GET RID OF THE ACCU SUCK