'14 Factory onboard battery charger questions

My new to me '14 Mojo came with the factory onboard battery charger and dual battery option and had a couple questions.

1. Will this charge both batteries?

2. Should the battery selector switch be set to 'off' to charge both batteries?

3. Will this trickle charge over winter? Seems like a pretty big charger for a trickle charger.

I am guessing it is 'Yes' to all the above but wanted to double check.

Thanks!

1) IIRC, its the pro mariner 12A 2 bank, so yes, it will charger both batteries.

2) OFF

3) its a multi-stage smart charger, so it will only charge as needed. As noted, its a 12 amp charger, so way more output then a trickle.