I have not one, but two EOS 5's, they were branded as the Elan A2 here. Interestingly enough, I upgraded from a 300 which I still have.
I have had no such problems with battery life, I put a new 2CR5 in each one when I bought them 5 years ago and have had no issues since, one is a little low because I use it as a slave to trigger a couple of external flashes when I'm shooting d*****l.
I really love it, it feels great in my hands and I've put several rolls of film through both of them on the same battery.......true story they were both stolen from me two years ago and recovered when the knucklehead who stole them posted them for sale on Facebook, imagine the look on his face when I showed up with the keys to unlock the hardcase he took that housed them, anyway I got them back without an issue (he went to jail) and both of them were still powered on just as I had left them a year earlier, with them film still in both, with no additional exposures. I've shot 4 rolls since in one.
I've never heard of this issue, usually the big problem with the A2/5 is the mode dial always breaks, both of mine were broke when I got them.