Cranking motor charger

I have a three bank charger for my Tm batteries. However my cranking batt I have nothing. Boat stays at fork year round any suggestions besides the "old school" charger for the cranking batt?

Buy a 4 bank

or a single bank.

Assumed that... 4 bank. Just trying to see what everyone is doing.

When my charger went down I bought a speed charger from Auto Zone. I already had one so I could charge my batteries it would just a little longer. Only problem is conditioning.

buy a single bank, much cheaper

cold weather will knock out battery

Get a 4 bank and sell the 3 bank to help offset the cost. I'm doing the exact same thing right now.

Add a single would be cheaper if you have room for it maybe a battery tender would work on the cranking battery?

I have a nice 4 Bank Minn Kota 440(4x10 amps) and its nice to just plug it in and forget it until next trip but honestly my starting battery is usually pretty much charged when I get home. The bank charging the starting battery never charges long. Given that I would consider simply putting an inexpensive small sized lower amp trickle charger to basically just maintain the starting battery. I assume you have been getting by just fine without it up until now. Think about it.

I put a trickle charger on mine every now and then for peace of mind, but it’s always charged.