Hi' everybody,
Atorch make several different variants of testers. The DL-24P is a good tester, but only suitable really for cell capacities below 80Ah, because it isn't able to sustain a discharge current above 16Amp (=0.2C) which is the standardized test discharge current.
You can still use it of course, but your resulting capacity will then show a higher Ah capacity, than what the cell would be able to provide at the proper test current.
I also tried their tester with multiple MOSFETs to obtain higher discharge current, but I had to completely give up on that path, the MOSFETs start producing some very noisy quiescent currents, and I never managed to run them stable with currents above 25Amp, and they end up self-destructive instead. I tried to get proper support from Atorch, but although they did try to help, it was fruitless, and just a complete waiste of time and money.
I now use and have several quite professional testers capable of up to 50Amp both charging and discharging, they work really smooth and have plentifully settings for good analysis of your battery, and they weren't even overly expensive.
If you are using cells up to 230Ah I would highly recommend such tester, and even cells of 280 and 320 you could test, but then with slightly insufficient discharge current (64Amp CC on 320Ah).
I also use it to analyse selfdischarge on a cell. Bad cells can easily draw over 1 amp continuously to maintain 3.65V, whereas good cells drop below 100mA without difficulty after a completed full charge.
The discharge curve itself also reveals such problem, as the voltage on the cell shows a constantly dropping voltage, where good cells does not drop much in voltage untill the very end of the discharge cycle.
The discharge curves shown here are both for 161Ah cells fully charged, rested and recharged before starting the discharge test, and you can clearly see the difference.
It also turned out that seller had scratched out the QR codes on the two worst performing cells, as if that would make any sense ?.
Hope you can use this information in your quest to stop fraudulent or aged cell offerings presented as grad-A and brand new.
Wath-Out.