If your batteries didnt charge after 50%, it must be a charger issue. Are you mixing NIMH batteries with NICD chargers? You should buy a nice set of batteries and a good charger (NIMH, 2000+Mah) to use with digicams.
Check this site for reviews of NIMH AA batteries.
http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM