V2. The batteries are even with the bottom of the tubes but there's space in the cap for the compressed spring.
I can stack two 18350 batts in the Vamo V5 no issues (so far although I stopped stacking when I got a couple of 18650's)
Mine are flat topped mind, but seems like there would be plenty spare space if they were buttons.
I find a single 18650 does me over stacking, I never made use of the extra voltage anyway.
But regarding what you said about "wouldn't the batteries equalize themselves" - no, that doesn't happen on any level and it's important, especially if people try to stack batteries in a mechanical. One battery will almost always hit low voltage before the other one does. An APV that is going to shut down when it sees 6.4 volts in stacked mode has no way of knowing if one of those batteries is still providing 3.8 volts - while the other one is all the way down to 2.6 volts. All it's seeing is the total series voltage output coming off the stack. In a mechanical there is no electronic monitoring at all, so the risk of that spread between two different batteries as they discharge can be even worse the further you push discharging them.
That's why you need to keep them in matched pairs and monitor battery voltages to make sure they are still remaining as reasonably close as possible to a matched pair over time. If one battery keeps depleting a lot lower and faster than the other one that's when bad things start happening to battery chemistry.
Last edited by Rickajho; 03-02-2014 at 10:29 AM.
Thats a great reason not to stack in a mech, and even better reasoning why it would be pretty irresponsible to mech without a protected battery.
Obviously though, normal due diligence and double checking the voltages after charging (and resting) batteries should show the user any batteries that are questionable and need retirement. Paired batteries in good health should push each other somewhat staying equalized within reason.
As for myself, I wouldnt stack in a mech and wont even run one without a kick, as I have zero desire or need to venture into sub'ing either.
Last edited by fogging_katrider; 03-02-2014 at 10:24 AM.