My wife and I have been cycling between 4 3000 maH Ultrafire 18650's for about 6 months, and I started noticing that some didn't seem to vape as well as others.
I built a rig consisting of a 0.5 ohm 10 watt resistor in series with a 1 ohm ten watt resistors in series which created a resistance source capable of dissipating ~ 20 watts between then.
If you put this 1.5 ohm resistance (mimicking a 1.5 ohm LR atty) across a fully charged 18650 battery, you might expect 3.7 volts under the 1.5 ohm load.
This 3.7 Volts was observed with only one of the loaded batteries. The other three batteries put out in the 3.25 - 3.45 volt range fully charged under load.
The power for these batteries is then:
Battery 1 @ 3.7 volts under 1.5 ohm load : 9.12 watts (Impressive)
Battery 2 @ 3.45 volts under 1.5 ohm load : 7.93 watts (OK, but not great)
Batteries 3 & 4 @ 3.25 volts under 1.5 ohm load: 7.03 watts (mediocre)
Compare this to a six volt source running a 3.4 ohm atty: 10.59 watts (now we're vaping)
The surprising thing I saw with 3 out of the 4 Ultrafire 3000 mAh 18650s was that their top load voltage dropped significantly after only 50 or so cycles.
I shoot for the 9 - 10 watt range, and it seems that these 18650's are up to the job, but for only a very limited time.
I've got some of the AW 18650's on order to hopefully fix the battery quality/lifetime issues.
I built a rig consisting of a 0.5 ohm 10 watt resistor in series with a 1 ohm ten watt resistors in series which created a resistance source capable of dissipating ~ 20 watts between then.
If you put this 1.5 ohm resistance (mimicking a 1.5 ohm LR atty) across a fully charged 18650 battery, you might expect 3.7 volts under the 1.5 ohm load.
This 3.7 Volts was observed with only one of the loaded batteries. The other three batteries put out in the 3.25 - 3.45 volt range fully charged under load.
The power for these batteries is then:
Battery 1 @ 3.7 volts under 1.5 ohm load : 9.12 watts (Impressive)
Battery 2 @ 3.45 volts under 1.5 ohm load : 7.93 watts (OK, but not great)
Batteries 3 & 4 @ 3.25 volts under 1.5 ohm load: 7.03 watts (mediocre)
Compare this to a six volt source running a 3.4 ohm atty: 10.59 watts (now we're vaping)
The surprising thing I saw with 3 out of the 4 Ultrafire 3000 mAh 18650s was that their top load voltage dropped significantly after only 50 or so cycles.
I shoot for the 9 - 10 watt range, and it seems that these 18650's are up to the job, but for only a very limited time.
I've got some of the AW 18650's on order to hopefully fix the battery quality/lifetime issues.
