If i understand you correctly with your auto lock.
I am speaking only for Hilti tools/battery's.
In all the tools of Hilti is a sort of diode in it, when the battery is going down in his V it will not be strong enough anymore to bypass the minimum required V border.
Testing those battery's with a discharger that have not the desired cut off will give you some problems.
As an example:
My batts/machines are all 22V, the machine will stop working when the V drops to 18.5.
If your discharger can be set to 5V to name something you mess up the cells.
So you need a specific cut off voltage.
There own internal bms does not do this, they don't protect against over discharge....
The same with deWalt i thought, will check on them this week.
For charging, the Hilti chargers only have a "stop" charging when a certain amount of V is reached, next to auto V sensing in case of 14.4 22 even up to 36V packs( i heard a rumour for 60v packs)
When taking a battery pack apart and replace the old for new cells, please do so with the V on the bms.
Some bms'es will stop working.
I am afraid that this is mandatory for most if not all tools
Yes i did my job to help 4 of my batteries to the recycler...
Hilti developed a own tester, it works with IR and a short time sort circuit, like those lead acid battery testers.
But this is my suspicion, they are really not willing to tell, and i am not going to buy one to open it up to satisfy my curiosity
I hope this was a bit helpful and possible some food for your thoughts.
With best regards Igor
Ps after those lessons, all my batts have new cells and even 1 whole amp more