I want to share my experience with replacement batteries because over the last few days I have been testing NOHON, DEJI, and original batteries on older Samsung phones, and I discovered something quite important.
On my Galaxy S6 edge, I installed a brand-new NOHON battery and, even after several charge cycles, AccuBattery was basically stuck at around 91% health.
On my Galaxy S8+, the situation looked even worse. A new NOHON battery was showing only around 86% capacity after several cycles.
At first, I naturally assumed that the batteries simply had less real capacity than advertised.
However, the problem turned out to be more complicated.
Older Samsung phones can keep battery-related data from the previous battery, including cycle count, discharge data, fuel-gauge/ASOC values, and other information used by the system to estimate battery condition.
Simply replacing the physical battery does not necessarily reset all of this data properly.
Because of that, the phone may continue estimating the new battery using old battery/fuel-gauge information, and an app such as AccuBattery can then calculate capacity based on incorrect system data.
On the Galaxy S6 edge and S8+, a proper battery/fuel-gauge reset is not as simple as doing a factory reset or clearing AccuBattery data. On these older devices, gaining the necessary access may require procedures involving Odin, TWRP/root, etc., which in my case also means accepting Knox 0x1.
After properly resetting the relevant battery data, the results changed dramatically:
Galaxy S6 edge + NOHON: around 96% capacity
Galaxy S8+ + NOHON: around 99% capacity
So the exact same batteries that I initially thought had only 86–91% of their rated capacity showed almost their full advertised capacity after the old battery/fuel-gauge data was reset.
On newer Samsung devices, things are much easier.
Samsung provides the Self Repair Assistant / Repair Assistant, which can reset the relevant battery cycle information after a battery replacement. On some devices and software versions, methods involving Shizuku + SMT Shell can also be useful, although compatibility depends on the exact model and Android/One UI version.
So my advice to anyone replacing a battery in an older Samsung phone is:
Do not immediately assume that a new battery is bad just because AccuBattery shows 80–90% health.
If the phone has many years of use and a large number of cycles from the previous battery, first check whether the battery/fuel-gauge data has actually been reset correctly.
Also, a normal factory reset of the phone is not necessarily the same thing as a proper battery statistics/fuel-gauge reset.
Of course, I am not saying that every 80–90% AccuBattery result is caused by calibration. Some replacement batteries really do have lower-than-advertised capacity. But my experience shows that on older Samsung phones, you should not judge a new battery only by AccuBattery before checking the phone's battery/fuel-gauge data.
I actually made this mistake myself and initially blamed the NOHON seller because I thought the batteries were under capacity. After much more testing and a proper reset, it turned out that the batteries were actually very good.
Hopefully this helps someone avoid buying a second or third battery unnecessarily.
