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Actual capacity ~1950 mAH (2.8v cutoff @ 1.5A)

  • UalnosajDX Sunday, December 25, 2011 6:13 PM Reply
    The actual capacity average of 21 batteries tested is ~1950 mAH (2.8v cutoff @ 1.5A). This is after charged with a MRC 992 charger (to 4.2v) and discharged using a CBA III Pro.

    Note that 1.5A is usually higher than what a flashlight would draw which explains lower capacity. Overall, the consistency between cells is excellent (of the 21 tested).
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  • desolder Top 10 Forum Poster Sunday, December 25, 2011 11:31 PM Reply
    That's not bad for cheap cells. Typically, capacity claims are made using a C/10 rate, so the capacity could be in the 2200mAh range if you re-test it at 0.2A.

    I just bought a bunch of the Trustfire True 2400 cells, sku.20392. Unfortunately the latest batch is only getting around 2000-2200mAh, so you might as well buy these cheaper Trustfire Gray 2500 cells and save some money.

    Here's a 2011 test of various 18650's, including the protected version of the TF Grey 2500s (sku.5776):
    http://lygte-info.dk/info/Batteries18650-2011%20UK.html
    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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    post edited by desolder on 12/25/2011 at 11:38 PM
  • nekdo12 Wednesday, June 20, 2012 4:36 AM Reply
    Capacity 1930 and 1980mAh, 4.20-2.80V at 1.5A
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  • nginx Friday, July 13, 2012 10:08 AM Reply
    I connected four of these batteries in 4S configuration to my laptop via a 19V output regulator. I monitored each cell voltage at all times and after 20 mins, I turned off the laptop at which point two of the cells were down to 3.5V. 18650 cells are known to be empty at 3.5V resting voltage. I have no way to measure capacity but full charge to empty within 20 mins suggests something is wrong with these cells and they can't be anywhere near 1950mAH in that case.
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  • desolder Top 10 Forum Poster Friday, July 13, 2012 11:15 AM Reply
    There's too many variables in your test to make a determination. What was the starting voltage per cell? How many amps were being pulled from the battery by the 19V regulator? Was the laptop actively being used? Running cpu intense apps or just idling? There could still be considerable energy below 3.5V. Try using a 2 ohm power resistor to discharge the cells even further, and time how long it takes to get to 2.7V.
    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

    Posts(6943) | Reviews | Tip post

  • nginx Friday, July 13, 2012 8:37 PM Reply
    @desolder

    I was actively monitoring the amps being pulled by the laptop and it kept varying between roughly 0.6A and 2A. The laptop was basically idling as it was a test run. It never exceeded 2A at any time. I didn't monitor the amps being pulled from the battery. Assuming 90% efficiency of the regulator, I reckon 1.5-3A max were being pulled from the batteries?

    I was keeping an eye on the 2.8V cutoff under load but unlike flashlights, its very difficult to gauge that for a laptop as current draw fluctuates so wildly every second that it makes the voltage under load fluctuate too.
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