1. Max voltage of the supercap is 2.7V but it can go higher than this, i once charged it to 3.2 at which point it was hot and i quickly discharged it by turning a piece of wire red hot, from that time I watch the voltage closely and go to 2.7/8 at most. And by usb power i mean USB from my PC, i butchered a USB cable to have a red and black wire on the other end charging the cap, or I can plug in the cable into iPhone charging brick, i don't have an actual power supply with variable voltage/current (probably should get one)
2/3. I just hooked up my 350F 2.7V supercap directly and monitoring it with an analog multimeter (i don't have a digital one lol ill have to get one too, my analog one sucks..). You guys say i should use a blocking diode to prevent discharge, but when i did this simulating solar cell with 1A power supply, the diode burned my finger, but since solar cell is small, current is low, it shouldn't heat up, but yeah, the problem is the supercap will still try to give the feedback.
I think to test this i should charge the supercap to the 2.7v, then try to close circuit through the diode but in the wrong direction, if the diode doesnt heat up, good, if it does.... 4. at the moment the supercap is at ~0.4V hooked up directly to the solar cell, the solar cell is producing at the moment with fully overcast sky 3.1V and some amount of amps that i cannot decipher using analog multi-meter.
i will keep checking the supercap voltage every 30 minutes and the temperature of the wires/supercap.
4a. when I charge supercap with USB power supplies (from PC or apple power bricks for iphone) those put out from 1-2.4A and 5V or so, the voltage itself plays no role as long as you monitor it and dont let it charge beyond 2.7V, but the current.... it loves current, basically these are the stats and charging times @ standard 5.2V USB charger.
0.4V - 2.7V @2.4A - 6 minutes0V - 2.7V @2.4A - 6:30 minutes
0.4V - 2.7V @1A - 14 minutes0V - 2.7V @1A - 21:30 minutes
Currently undergoing test @ 3.1V and ?mA (i precharged the supercap to 0.4V because for some reason under 0.4V supercap is very hard to charge, but it goes fast after 0.4V