I had Vistalite lights with I think a 7.2V or maybe 6V NiMH battery pack. The charger I am absolutely sure was just a transformer, with no charging circuit in it. I don’t recall the voltage output. The thing is, the voltage across the battery terminals will climb as the battery gets more charged, so this will result in less and less current flowing as the batter y voltage approaches that of the supply, which I assume was a crude way of regulating the charging. The batteries would get quite hot if you left it on charge for say 24 hours – it was meant to be a 4 hour charge – but I don’t know if any damage was done. I think it said something like don’t leave them on for 24 hours.
So I think you can charge them with a normal transformer but ONLY if the voltages match. Don’t stick a 12V supply onto a 7.2V battery. You’ll either bugger it or set fire to something.
some hornby controllers appear to be 16v ac output.
although the dc ones do seem to be fairly low current so all may not be lost.
It probably wont’ be properly current limited – so drawing more than the rated current will either burn out the transformer or more likely blow a fuse (or thermal cutout). If it’s got a current rating written on it, that just means what you can draw from it without risk. You can draw more, but it’ll get damaged as above.
