back onto the batteries again, I had a set that I was running last night, went to run it again this a.m. and noticed a huge drop in performance. I tested the voltage and got 3.29v and 3.30 which I thought would still be enough power to be firing up the Evo. That is still over 6v in combination of the 2 batteries, so why is the performance dropping at this voltage? I am learning all kinds of new stuff because of these vapes.
Nothing in life is simple, electronics more so, and batteries especially. The next step in the puzzle gets harder to deal with for most casual folks, we need to measure the drop
under load. This measures that internal resistance thing that's what makes the heat and causes the in service drop. Ever notice how your car battery can be fine to run the lights but can't crank the engine? In fact, the lights wink out when the 12 Volt battery collapses when you hit the key. Same deal. Capacity at
high rates isn't there. To test for this you need a reasonable level load, it doesn't have to be exact. Over the years I've used light bulbs, resistors, coils of wire, all sorts of stuff. Yesterday, when testing the proposed supply for the PA for Evolution we used a real live Evolution cart to get the 'under load' voltage. It drops trivially.
For your uses, I suggest you split those two cells and combine them with two others (marking these) to see if one is causing the problem (most likely). You might also be able to ID it by heat, it should be hotter than it's mate just after running hard.
Well make you an electrical type yet.....
HTH.
OF