Hangar 9 multi load field voltage tester

This is an excellent value. You can get 500 ma or 1000 ma or 2000 ma test load readings. Can be used on packs from 600mah to 5000 mah. Reverse polarity protected. Read out is in 1/100ths of a volt not just 1/10ths of a volt. When 2 cell Li Ion packs get to 7.0V under a 1 amp load you should be able to get one more flight, but it's a little risky. If possible, recharge. At 6.8V the battery has very little capacity.