At 3 years, if they were properly maintained the batteries are the equivlent of a human teenager, Not even "in the prime" yet (that would be 4 years) Batteries properly maintained are like a popular convience store 7-11 (years though) (The store, originaly, was open 7am to 11pm in case you wonder where the name comes from, I'm old enough to remember those days).
However if the batteries are LOW.. or if they have not been maintained, or if the terminals are a bit dirty. (All very common) then you must supplement. Two ways to do that.
one, you figured out
Two, Press and hold the EMERGENCY STAT (may be labeled aux start or BOOST) switch, while starting Generator (what I do) this is the same button you use to "Jump Start" the main engine from the house batteries.
But have your house batteries tested.. Clean and test.. Easier to test 'em than replace 'em.
