I bought an ISDT C4 Air, or rather, a Limeta R4 Air (but it’s the same hardware, and the software is from ISDT). During initial tests, I noticed that it’s measuring the charging time incorrectly, losing about 10 seconds per minute. I started charging and simultaneously started the timer. When the charger’s charging time reached 2 minutes, the timer showed 2 minutes and 23 seconds.
Furthermore, with the current set to 1A, the counter only reached 1000 mAh after an hour and 15 minutes, which, considering the incorrect timer, would take even longer.
Yes, you’re right.
But let’s get back to the incorrect time and capacity measurement. The screenshot below shows that while the charger says 2 hours have passed, in reality (the stopwatch app at the bottom) 2:25 have passed. Furthermore, the current is set to 1A, so after 2 hours the screen should show around 2000 mAh, but it actually shows 1600 mAh. In fact, due to the inaccurate charging time (2:25 has actually passed), the counter should show around 2416 mAh.
And is it possible that the time displayed by the charger (it shouldn’t be like that) actually only shows the time for which it supplies voltage to the battery, and the time for which it performs cyclic battery measurement is not counted? That would explain the discrepancy with the supplied mAh energy. These cycles are quite frequent as SammysHP states.
However, I agree that ISDT products are problematic in many ways. The inaccuracy of measurement values such as capacity, battery resistance, or temperature is catastrophic. I have an ISDT N8 and I don’t use it much precisely because of its unreliability. And I sent the ISDT C4 EVO back to Amazon because it had problems charging 1.5V Li-Ion batteries. There, it was a matter of life and death, because the voltage going to the batteries was 6.2V and the temperature of the batteries was over 60 degrees Celsius, even though the charger showed 32 degrees. Fortunately, I took the batteries out in time.
It’s quite possible that it only counts the time it actually charges.
Unfortunately, the capacity calculation seems to be inaccurate as well. I connected a USB meter (AVHzY C3) between the charger and the battery and enabled logging. The results are below, along with other chargers (different batteries):
C4 Air
1437 mAh 01:48:17 (from charger)
1716 mAh 02:10:45 (measured)
SkyRc MC5000
1700 mAh 01:55:36 (from charger)
1830 mAh 01:55:35 (measured)
OPUS BT-C3100
2000 mAh 02:21 (from charger)
1965 mAh 02:20:58 (measured)
Below I am also pasting the graphs, in the case of voltage we have two lines due to the charging voltage and battery testing:
It appears that the OPUS rarely checks the battery voltage. It also appears to be using CC CV. Unfortunately, trickle charging is also present.
The SkyRC MC500, on the other hand, has strange charging voltage peaks.
