How old are batteries they now and how old do you think they will be when you place one or two of these Tx’s back into service?
Personally I wouldn’t put much trust in a pack over five years old. You might be better off just planning to use new packs when your ready to use the Tx’s again.
What ever you decide definitely disconnect the packs from the Tx’s
Here is some very good reading to you help sort this out. Be sure to read, “black wire disease” and “Storing your R/C packs?”
http://www.rcbatteryclinic.com.