Best High Capacity 21700

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Havok
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chops728 wrote:
I’m curious how many mah you gained from 2.9v to 2.5v —- got to be minimal — 90% of mine test 4700 – 4850 range 4.2v — 2.9 v —- the Opus goes to 2.9 then drops to 2.8 instantly

Just finished the test, and it was 100mAh from 2.9V -> 2.5V.

This cell came in at 4893 at 1A.

Cell #1: 4841
Cell #2: 4833
Cell #3: 4893

I think I’ll order more.

JaredM wrote:
My three came last saturday or so.. packages in the grey plastic with no markings and inside a clear bubble wrap with packing tape. I do have testing equipment to easily test up to 3A. The higher current testers are a PITA to work with for these small tests and I don’t think these seem like they are going to be useful in high current lights by the sound of it. Won’t get around to it til next week but I can share some curves if people care to see them

I’d like to see what they can do.

Sirstinky
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In case everyone’s wondering, I heard from someone at Vapcell that T50s wil not be restocked Tired if you want the best high capacity 21700, try to find some Samsung 50S.

chops728
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Havok —— Thanks for that information —— for 100mah not really worth stressing the cells ——- I’ve been playing around with solar and EV (scooters) from what I’m learning it’s much better not to charge or discharge to the limits —- even 4.15 – 3.10 will add lots of cycles — Don’t get me wrong I still like to max voltage for my extreme light testing — but in my sphere and outside the difference in lumens is minimal

Havok
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chops728 wrote:
Havok —— Thanks for that information —— for 100mah not really worth stressing the cells ——- I’ve been playing around with solar and EV (scooters) from what I’m learning it’s much better not to charge or discharge to the limits —- even 4.15 – 3.10 will add lots of cycles — Don’t get me wrong I still like to max voltage for my extreme light testing — but in my sphere and outside the difference in lumens is minimal

I usually don’t stress the cells like this under normal usage either. I only do it to see what their capacity is when I first get ‘em.

I only let my cells go from 4.2V to 3.7V.

NiOOH
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I charge to 4.20 V, but seldom discharge below 3.4-3.5 V. My MC3000 is calibrated to within 2-3 mV, so the max voltage (4.200 V) is not exceeded during charge. Unfortunately, not all chargers are that precise. I remember having a charger (don’t remember the brand, could have been Nitecore) years ago, that would charge to something like 4.22 V. Not terrible, and still within spec, but not ideal for cycle life.

SIGShooter
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NiOOH wrote:
I charge to 4.20 V, but seldom discharge below 3.4-3.5 V. My MC3000 is calibrated to within 2-3 mV, so the max voltage (4.200 V) is not exceeded during charge. Unfortunately, not all chargers are that precise. I remember having a charger (don’t remember the brand, could have been Nitecore) years ago, that would charge to something like 4.22 V. Not terrible, and still within spec, but not ideal for cycle life.

The Nitecore I2 I bought many years ago charges my batteries to 4.22v.
NiOOH
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That’s not ideal, especially if the end of charge current is low (1/10 of the CC current or less). You may expect a reduction of cycle life. It will not be huge, more like 15-20%, but still there. I’d rather prefer to have a charger that charges to 4.18 V (thus undercharging), than to exceed the 4.2 volts limit.

Edit: if you measure above 4.20 V after the end of the charge (even shortly after), this means that the end of charge voltage was even higher. That’s not good. A properly charged LiIon cell, right after the end of charge should read slightly below 4.20 V

SIGShooter
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NiOOH wrote:
That’s not ideal, especially if the end of charge current is low (1/10 of the CC current or less). You may expect a reduction of cycle life. It will not be huge, more like 15-20%, but still there. I’d rather prefer to have a charger that charges to 4.18 V (thus undercharging), than to exceed the 4.2 volts limit.

Edit: if you measure above 4.20 V after the end of the charge (even shortly after), this means that the end of charge voltage was even higher. That’s not good. A properly charged LiIon cell, right after the end of charge should read slightly below 4.20 V

Yeap that’s why I’ve only used the I2 less than 5 times since I got it around 2013 or so. After reading the off-the-charger voltage at 4.22v it went into my junk collection. These days I mostly use my Opus 3100 where the cells come off at 4.16 – 4.17v.

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