EVE INR18650-25P 2500mAh - 20A battery (branded as TerraE)

Not long ago, one of my readers decided to buy batteries to replace the ones in his angle grinder battery pack. I was interested too, so I tagged along and ordered one to test.

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We considered different types, including Samsung and Murata, but then spotted batteries made by EVE, also rated for 20 A, but noticeably cheaper. The store offers two versions of these batteries: EVE-branded ones and the same batteries under the TerraE brand, which are even cheaper.



I found a datasheet online, and I'll share the information from it here.
Note that the datasheet specifies a maximum continuous discharge current of 30 A, not 20 A as stated on the store page, but with a caveat: the temperature must not exceed 75 degrees. In other words, you can discharge at up to 30 A, as long as the battery temperature stays below 75 degrees.


They don't look particularly distinctive. The finish is neat, and there's a label and a barcode; presumably the date is encoded somewhere here too.


The dimensions and weight are nothing unusual either—standard 18650 cells.


The first charge took about 1800mAh, so the batteries were initially charged to roughly 30%.
The “conditioning” cycle measured 2584mAh, slightly more than the rated capacity.


There are no graphs in the datasheet, but there is a table showing that the battery delivers 100% of its capacity at 0.2C and 10 A, while at 1C and the other current levels, the available capacity drops.
You also get 100% of the capacity only at temperatures of 25 degrees or higher. As the temperature drops, the available capacity falls too; at -20, it is only about 60% of the original.


Two charging modes are specified: standard, at 0.5C, and fast, at 4 A. Not all batteries support this, which can be critical when replacing cells in a battery pack, since the original charger may charge at that current and not every battery supports that mode.

At 0.5C, charging took 2 hours and 12 minutes, which is very good.


Charging at 4 A took 55 minutes, which is also good in my opinion.


I tested it in nine modes: 0.2, 0.5, 1, 2, 4, 6, 8, 10, and 12C, where C = 2.5 A.
The only exception was the 10C and 12C modes, where I had to stop the discharge once the battery case reached 75-77 degrees.


Temperature at discharge currents of 10, 15, and 20 A. At 25-30 A, the temperature rose quite quickly, increasing by one degree in just a few seconds—and at 30 A, almost every second.

In my opinion, the heating is moderate. At 20 A, the battery reached 85 degrees; the Samsung 25R, for example, reached 94 degrees, while the Murata VTC5A reached just 75 degrees. So this one falls somewhere between the Samsung and the Murata.


Battery impedance on arrival, after “conditioning,” and after all the tests.


And, of course, a comparison graph featuring the batteries under review (blue), the Murata (red), and the Samsung (green).
The graph shows that the batteries under review have a more pronounced voltage sag at the start of discharge, but their voltage is higher than the competitors' after that. Their capacity is closer to the Samsung's, and both outperform the Murata.


Conclusions.
Subjectively, these batteries are interesting in terms of the balance between performance and price. Objectively, they are roughly on par with the popular Samsung 25R.
The rated current of 25-30 A is certainly nice, but in that mode the voltage sags significantly and the battery heats up quickly, so I'd recommend limiting the current to 20 A. Charging at up to 2.5 A is perfectly fine; I don't see any point in going higher, and it would only put extra strain on the battery.

In short, I can definitely recommend them. Yes, the batteries made it from Nkon to Ukraine without any problems via Meest Express. Besides, the limit is now 150 euros, not 100, so it's better to put together a larger parcel to offset the shipping cost.

That's all for today. I'm here with you, friends. Everything will be fine; Ukraine will win!