i also have DX ultrafires 10440 but that 500mAh sticker is greatly overrated, i can find the testing somewhere on candlepowerforums (if you like) to proove how much are they for real. those batteries are commonly used for some led flashlights. When the voltage falls to 3,7v they are already half empty and the vapor is reduced. I think that ruyans and ultrafires are in the same ballpark when new, no matter what does the sticker say...
mine say 600 ma.. the ruyan say 360.. i have eight ultrafires but only the two ruyans.. three of my ultrafires have failed after little use.. i have five left.. my two ruyans have been discarded in favour of my ultrafires
my first eight from e-cig china all died within the first week of using them..
the problem is the little batteries are being ask to deliver three times their rated capacity several hundred times a day.. every day.. its battery abuse..
testing their when new true capacity is easy.. take load of say 100 ma.. put it on the battery and see how long a fully charged one takes to run down.. if a 360 ma one manages three hours its okay..
i have never done this to these batteries but my ultrafire ones do a better job of powering my ruyan cigar than the ruyan ones do..
i start off with a new known good one.. check the smoke production and how much some strong puffs warm up the atomizer casing.. this is very noticeable with a good battery..
when a few strong test puffs no longer warms up the atomizer casing i know the battery power is falling off.. so is the smoke production.. again its very noticeable..
when the fall off happens noticeably sooner than it does with a known new good battery.. the battery gets my bulb test..
the bulb test is a simple one.. one 12 volt 21 watt car tail light bulb.. this draws around one amp at 3.6 volts.. roughly the same as an atomizer heater coil does..
if the bulb glows as it should and does so for at least one minute it passes my bulb test and goes back into service.... if not it goes in the bin.. at first i used to fully charge again to make sure.. but now i am so sure the ones i suspect are gonna fail i dont do the second check..
my testing methodology is pretty good.. i have no reason to doubt my results.. these things dont live long given all day and very day heavy use.. but they are cheap at dealextreme prices.. four dollars for a pair.. i hoped the ones supplied by ruyan might be better.. they are not.. cheap chinese batteries are cheap chinese batteries even if they do have the ruyan name on em..
how ruyan handle such a short product life i have no idea.. they perhaps hope their customers dont use the things much and wont bother with the two way postage to china..
trog