The gemini 20 takes trickle charges wonderfully. I drop grain by grain with tweezers to get to my 34.20 grain H4895 charge for my .32 Special. The scale holds zero like a dream as well.
It is hard to believe that a cheap scale that no one has heard of works as well as a beam scale but I can assure you it does. I have 6 months and 3600 rounds of trust in it and many ragged holes of proof that it works.
Oh and I have yet to change the batteries. I check the scales regularly against its included check weights my beam scale and it stays true.
For $23 delivered I urge anyone in need of a primary or backup scale to give it a try. You can always send it right back.