I'm having to change the batteries every 50 pictures. Tried cleaning out battery canal with 3M cleaner to no avail.
Flashes are extremely hard on batteries, so they will naturally drain them quite quickly. Alkaline and Nickel-Cadmium batteries aren't the best suited batteries for this job, and rechargeable variants will lose their capacity quite quickly compared to lithium based batteries.
There are AA/AAA batteries designed specifically for digital cameras, get your hands on those.