I don’t understand batteries all that well. So here is a test I did to give me some info on the new Solarforce Green & White 16340’s (really 17360’s) 3.7v 880mAh batteries. I have two duplicate flashlights Trustfire L2M flashlights each with a Trustfire XM-L T6 drop in. In one flashlight I put a fully charged Solarforce 16340 and in the other a Xtar 16340 3.7v 600mAh battery. Turned them on high beam for 13 minutes and shut them off and then measured the volt level by putting them into my Nitecore Digicharger D2 . Did the same test with a Ultrafire 16340 3.6v 1000mAh and also a Xtar 18350 3.7v 850mAh battery. All batteries were charged to 4.20volts. What can I tell about the actually capacity of the batteries by the level of discharge after 13 minutes? (For the Xtar 18650 battery I had to put the Trustfire XM-L T6 drop in into a Solarforce L2M host because the Trustfire flashlight is not bored to take a 18mm width battery.)
Solarforce 16340 880mAh 3.87
Xtar 16340 600mAh 3.84
Ultrafire 16340 1000mAh 3.68
Xtar 18350 850mAh 3.76
The Solarforce battery is new and only charged a couple of times. The Ultrafire has been charged about 6 times and the Xtar’s have been charged about 20 times each. So all the batteries are relatively new. When I charge the Solarforce 880mAh’s they take longer to charge like a 18350 and not as quickly as the Xtar 16340 or Ultrafire 16340. Can I determine that the Solarforce capacity is closer to the 880 level than the 600 level of the Xtar 16340’s? Or does this test actually tell me nothing about battery capacity or quality? Thanks
1. Voltage is a VERY rough approximation of % capacity left. If you don’t know the REAL capacity, you don’t know much with a voltage reading. 50% of 1000mAh is not the same as 50% of 600mAh
2. The Ultrafire is likely crap - period. It may be usable but that capacity is bogus which can be a real indicator.
3. After use the voltage rebounds. The longer you wait the more the rebound. You can get all kinds of readings depending on how long you waited to test the voltage. Try it-do another test, immediately after stopping check voltage, then in 5”, then in 10”.
You can’t draw any conclusions based on your observations. The flashlight may be drawing different current from different cells, then using it to measure capacity is meaningless. Longer charge time doesn’t necessary means higher capacity, it may be higher internal resistance or other factors.
+1 to what chukhov and Pregulla said.
If you want capacity (fairly easily) you need an analyzing charger. If you want to understand batteries better……get and analyzing charger. You don’t have to be able to absorb all the details of HJK’s graphs and still have a working grasp of how batteries work. But once you do have working knowledge, then you can figure out the graphs.
Thanks for the advise. I agree I do need an analyzing charger. I prefer not to go with a Hobby Charger, but with something closer to the Nitcore Digicharger D2 that I already own except with the ability to discharge and analyze the battery capacity. Anyone have a suggestions? I tried looking through the charger reviews list but I can’t tell which ones can analyze the battery capacity from the titles.