The Ch72 says it will output 6 volts at .1 amps so it would take ten hours for a 1000ma, to charge it fully. If your pack is larger as pointed out it will take longer but it is simple to figure it out take the size of your pack and dived it by 100 (100ma=.1amp) so a 1400ma pack would take 14 hrs, a 1700ma pack would take 17 hours and so on. Keep in mind I think this setup is for Nicads only I am not sure if it works with NIMH type of packs. For 12 bucks I do not think it is one you could hope to use with all types of batteries. For around 50 bucks you can get a charger the will handle Nicads, NIMH, or Li-pols so you can do any type of battery except for Lithium Ion cells. But if you don't care to spend a lot the $12 should do the pack you have, the fifty buck set up you would have to switch to the proper settings, and if you have it set wrong you can cook things (battery/charger) or other things...
And you can also get chargers that do any battery and does so automatically but you can spend a lot on them but it is cheaper than having one charger for each battery type like I have done over the years.