I would not advise using alkaline batteries. Silver Oxide batteries (like Mercury) have a stable output voltage until they die. And when they die they die quickly.
Alkaline batteries don't do this they die slowly and don't give a stable voltage. Which means any metering with an alkaline battery cannot be trusted to be true.
Hi: I'm a new guy, had an XA for a few months, I could not resist it for only £3 on a car boot sale. I use alkalines as SOs are unobtainable in my town and I keep forgetting when I go elsewhere.
Anyway, I find that the slight voltage variation between Alk's and SO's causes my box to select about 2 to 3 stops of over exposure so with 200ASA in I set to 800ASA to partially compensate.