I took my Canon FTb up with me last weekend up skiing. I picked up a 625 Wein cell battery to see if the meter. The FTb was made in the early 1970s and the original batteries were mercury based and of course due to environmental concerns are no longer available. The Wein Cell gives off the same voltage without the environmental impact.
I used this camera before with a hand held meter and the shutter speeds are just fine which is surprising for a 37 year old camera. The meter works but takes a little getting used to. The FTb uses almost a modified spot meter principle as opposed to center weighted used in Minolta, Nikon, Olympus, Leicaflex and the Canon F1. It takes a little getting used to if you are used to center weighted metering.
One last thing, I found that helps a lot with bright sunny days and there's snow on the ground to slap on a neutral density filter if you are shooting with 400 ISO film. Otherwise getting a decent exposure would almost impossible without a slower speed film.