A turbo 35 or even an turbo 30 will still discharge and give you the numbers needed. They go for around $40 or less on ebay. The GFX will graph, but on a turbo 35 you can watch the discharge, write down the data and make your own graph or table. You don't even need one that is lipo capable if you watch the battery and don't discharge it down too far or charge with it. Gfx's go for over $150 on ebay.