whats a good trolling battery charger? i no nothing about em, so i was wondering, i see some that say fast charge, slow trickle, or something like that. which is better?  id be charging 2-3 batteries, dont know if you can get a charger to do more than one... thanks.

Slow trickle charge is the best in my opinion but others may have a different view

If you can get an onboard charger, they can charge multiple batteries. Don't know about other type (as far as multiplies). I went to Wal-Mart and got a Schumacker (old company) Ship'n'Shore. It starts out on a higher charge and then drops down auto. to trickle charge. About the best price I could find...

skillet

Your best solution, IMO, would be to install a multi-bank onboard charger in your boat. Each "bank" in the unit is actually an individual "charger". Get one that has a "bank" for ALL the batteries you have in your boat - including your starting battery. That way you can easily charge all your batteries with a single AC connection. Dual Pro (http://www.dualpro.com/) makes a good one.

Guest is a popular brand on this board.  I just got a 2 bank Guest and have no complaints.  I had a Ship to Shore before that and although it was a little finicky it got the job done just fine too.  Every now and then it would show 18 volts on the gauge.  I just had to unplug it and unhook it from the battery for a few seconds then hook it back up and it was fine.

I've got a 2 bank minn-kota on the boat Works very well, switches to automatic float.

I bought a back up black and decker charger at WalMart that works very well also. It was only like 40 bucks...it only charges one battery at a time, but it has several settings and they all have automatic float.

For convenience, my vote would be to find a 3 bank on board charger.

If you get an onboard charger, then definitely get one that has enough bans for each battery.  I let the dealer talk me into getting one that has only two banks (one for each trolling battery) but not one for the cranking battery.  Well twice I have put the boat in the water and no crank!!!!  Drives me nuts,  I am about to get a three banker!!

They make a four bank charger now too.  For those of you lucky enough to buy a boat with a 36 volt trolling motor.  

Your best solution, IMO, would be to install a multi-bank onboard charger in your boat. Each "bank" in the unit is actually an individual "charger". Get one that has a "bank" for ALL the batteries you have in your boat - including your starting battery. That way you can easily charge all your batteries with a single AC connection. Dual Pro (http://www.dualpro.com/) makes a good one.

Dual Pro will sell you a rebuilt onboard charger at a good discount.  That's where I got mine and I have been very well pleased with it.

On-board chargers: I just went thru the selection process of battery chargers for a new boat. My concern was with the space required to mount one. The Dual Pro has the smallest 3-bank footprint of all the brands in the output per bank I was interested in. I called the company to check on the warranty of the rebuilt as opposed to the new ones. The rebuilt has a one year warranty and the new ones have a three year warranty. I chose to purchase a new one and did an internet search for the best price and shipping price that goes with it.

The majority of bass boats I have been in are outfitted with the Dual Pro. I have heard several persons that are pleased with the Guest brand and their excellent service.

I also have 3 fuctioning automatic portable battery chargers for deep cycle batteries and all are the Schumacher brand-one is about 25 years old. I have another non-functioning Exide brand that has blown the diode twice.