Queen Battery QB18650 2500mAh capacity test + comparison with QB18650 2600mAh


100 W
Oct 8, 2017
Original article: https://www.thunderheartreviews.com/2020/12/queen-battery-qb18650-2500mah-5C.html

In Queen Battery's lineup QB18650-2500 stands very close to QB18650-2600 not only by capacity rating but also with max supported discharge current - the 2500mAh cell supports 5C or 12.5A and the 2600mAh one - 13A. So not only testing the 2500mAh cell is interesting but also comparison between them.

The battery was bought from Queen Battery which is my reliable supplier of genuine cells and tested with ZKETECH EBC-A20 and a self-made battery holder. It's a PC-connected battery tester supporting 4-wire measuring and discharging at up to 20A.

This is the first test done using my battery holder v.4.0. A detailed video about it is available on my channel.

I've followed all the prescriptions of the IEC61960-2003 standard concerning battery's capacity measurement. Before each discharging cycle the battery was charged at standard charge current mentioned in its datasheet to charge end voltage. Before each discharging or charging i've held a 1-1.5hr pause. The environment temperature was 25±2°C. To be sure in results i've done each test minimum twice (usually 3-7 times).

Queen Battery QB18650 2500mAh

The heat shrink tube doesn't have much information on it. There is only the model number, nominal capacity, max discharge current and nominal voltage mentioned.

QB18650 2500mAh cell's main specs according to the official datasheet (pdf):
Nominal capacity: 2500mAh
Minimum capacity: 2400mAh
Nominal voltage: 3.7V
Standard charge current: 1.25A / 0.5C
Max charge current:
2.5A / 1C at 15+°C
500mA / 0.2C at 0-15°C
Charge end voltage: 4.2V
Max continuous discharge current:
1.25A / 0.5C at -20°C - -10°C
2.5A / 1C at -10°C - 10°C
12.5A / 5C at 10+°C
Discharge cut-off voltage: 2.75V
AC impedance: ≤25mΩ
Max weight: 48g

Cycle life:
Using 1.25A (0.5C) charge and discharge current with 10 minute rest time after each charge or discharge session cell's capacity should be ≥80% after 500 full cycles.

DC IR at 2500mA in fully charged condition was 23.2±1.2mΩ (measured using EB Tester Software's Resistance test feature).

Measured dimensions: 18.3mm (diameter) × 65.3mm (length).

Measured weight: 45.66g

QB18650 2500mAh battery's capacity test results:

At 0.2C (0.5A) discharge the capacity is much higher than declared - 2752mah, which is normal for Queen Battery - for some reason they always declare lower capacity than the cell actually has and i like that approach.

At all the other discharge rates the capacity goes around 2500mAh, even at 12.5A, and it's very good. The curves look nice, almost linear, which is good for SOC detection by voltage.

Comparison with QB18650 2600mAh

The 2600mAh cell's max discharge current is limited by 7A at 0°C≤t<20°C and by 13A at 20°C≤t<60°C. My tests are held at 23-25°C, so 13A is the case that's why i decided to compare the 2500mAh/12.5A cell with the 2600mAh/13A one though the latter was tested using version 3.0 of my battery holder.

As you can see their curves look almost similar except the final parts. The newer cell with lower rating outperformed its rival in every test.

Comparison in numbers:

QB18650 2500 is the clear winner and looks like it's the upgraded version of 2600mAh cell.


QB18650-2500 appears to be an excellent cell for two reasons:
1. Its actual capacity (measured at 0.2C) is higher than declared by 10%!
2. All the way up to 5C discharge the capacity remained around 2500mAh and the curves without distortion.

QB18650-2600 looks pretty much outdated and even being labeled higher it lost the battle.

Here is the video version of this review:

Check out my YouTube channel for batteries, chargers and other stuff reviews.
I've launched my blog where you can find all my reviews in one place. Every new test/review will be first published on YouTube and in the blog. I'll be happy to see new subscribers, comments, suggestions and just your thoughts.
Is there a secret to ordering or even getting price / availability info from the QB website?

Are you vouching for them being trustwirthy source for say LG or Samsung branded Grade A cells?

How about A123?
john61ct said:
Is there a secret to ordering or even getting price / availability info from the QB website?

Are you vouching for them being trustwirthy source for say LG or Samsung branded Grade A cells?

How about A123?

There is no secret - you can order in their store on Aliexpress or drop them an email to order directly (payment should be done by PayPal).

As far i had no problem with them and if there are Grade B cells they declare it clearly. After testing A123 cells i ordered Grade B cells for one of my projects as they seem to have higher capacity than Grade A. To my question "why those are Grade B?" i got no clear answer. I think it's just factory grading and if they get them as Grade B cells from factory they sell them as Grade B. Whatever, I'm happy with Grade B A123s i've got.
Thanks for posting this Thunderheart, very useful. I'm considering ordering for a 16s battery build, hopefully nothing has changed with the qb 2500mAh cells over the past few years. Did you do any cycle life testing on these cells?