battery charger question

[nofish2]

I plan to purchase an onboard 3 bank charger. I use 3  12 volt batteries. One for the engine one for the depth finder the other for the trolling motor. What do you suggest, 15 amp or 30 amp. What has been your experience with brands?

Would it be cheaper to go back to the Bannana Boat?

Thanks,
RJ

I run a Minn kota three bank charger. I really  like it just plug it in at the end of the day and you are good to go in the morning. When the battery is fully charged it will switch to a trickle to maintain it. 

I am not sure but I think my will change amp output depending on the charge needed. I gave $100 for it and have had it two years. I found it on ksl and it was new.