As far as I know this camera uses a moving needle type meter similar to my Canon F1 (first version). If so I have found a silver oxide battery is fine, the increased voltage just causes it to show a bit 'more light' than there actually is. Setting the ISO to half the actual ISO of the film compensates and gives correct exposures. The same also worked for my Canonet QL17 GIII. I'd be surprised if it doesn't work for you.