On board charger question?

A buddy gave me a Batt Cat 3 bank charger. He upgraded and didn't need it. I have no experience with the on board chargers. I only have 2 batteries and would only use it on my trolling motor battery. It says on the label that is is 2.2amps per bank. Could I connect all three leads to my trolling motor battery? I am thinking the 6.6amps would be good for the trolling motor battery but don't want to short anything out. It also is "fully automatic, reverse polarity, yada yada". Thanks in advance.
Fred out...........

With most chargers you terminate any unused leads on the battery where the no 1 lead is connected. In your case then all three would go on the TM battery. With that rated at 2.5 amps per lead makes me tend to think that might be a battery maintainer but still should charge your battery. Just take a lot longer to do it.