Vileda A3 floor cleaning robot battery problem.

I have two Vileda A3 floor cleaning robots, they were left unused for some time, and when we tried to use them we found the units shut down with battery under voltage, I am 100% sure it is the battery voltage causing them to shut down, and by discharging and recharging battery I was able to run them for maybe a minute.

Since I did discharge the 24 volt battery, I know from time taken they are not completely US, I can draw ½ amp for quite a time, but cleaners rated 1 amp.

New battery is around £45 which is more than the cleaners cost new, seem to remember Lidi or Aldi, so wondering if there is a way to adjust the voltage at which the units switch off? I think if I got one working the batteries may come up again, but no point in re-inventing the wheel, so wonder if anyone has worked out how to adjust the cut off voltage?

Depends on what's being used. If it's the most cost effective circuit possible the the DCDC converter literally won't work anymore if the input voltage is too low.

If it's a liion pack with a cell that discharged to low the BMS will not allow it to be used again and there is good reason for that.

I may be wrong, but from what I can see, the charger is 24V (Edit: sorry the PSU is 24V, charger circuit is built into the vacuum), but the battery is a 14.4V NiMH?

Not helpful, but an interesting diversion for robotics fans:
https://ynformatics.com/2017/arduino-vileda-cleaning-robot/

I'm afraid I've had no luck at bringing back NiMH, but have swapped them out for smaller Li-ions. That's not the most convenient solution in your case.