For all of your PS1 units, I suggest you simply replace the batteries, either with new rechargeable ones from MTH or BCRs from J+W. If the batteries in those units are original, they are at least 17 years old and perhaps much older. There isn’t much to be gained, and more to be lost, in not replacing those right away.
As Barry suggested, you need to test the batteries under load to assess its ability to hold a charge.
