Amazon says I bought this one in 2012 and its still going strong. I had the same question. You hook your batteries all up to run the boat and then you run a pair of wires from this thing to each battery. It charges them separately even though they are hooked together. I don't understand how but it does. A few things I learned doing mine. You don't have to take your batteries out, just leave them plugged into this charger. It shuts on and off depending on charge. Its not actually on the charger constant.
Two batteries weight alot and where you put them greatly effects how the boat sets in the water. I have a crank battery in the back. It being on the right side effects where I can put my two trolling batteries. You get a guy to go with you and he sits on the side you have allt he batteries are on and you can tell you sit in the water wrong and he's going to feel fat.
If I were doing a boat today I'd have 4 batteries and a 4 bank charger. 2 trolling, 1 crank, and 1 dedicated to the fish finder and radio. Running my fish finder off of my trolling batteries causes false fish to show up on the screen. You can tap the gas pedal and fill the screen with marks.
Also if I was doing one today I'd buy an 24v inverter (24v to 110v) and run it off of the two trolling batteries and have an outlet in the boat. Charge phones and what not if I had to. Whatever I wanted.
Also I have an old set of jumper cables in the boat so I can jump the crank battery in the back of the boat with one of the trolling batteries in the front of the boat.
The cord I plug my charger in with is hanging from the rafters. When I forget to unplug it and pull out and head to the lake the charger unplugs itself and falls into the boat, not over the side.
Put the charger somewhere where you can see the LEDs on it while its plugged in. Green is charged. Red is charging. Flashing red means there is something wrong with the circuit / battery is too dead.
I buy reconditioned deep cycle batteries from Interstate. Not the fancy ones your talking about. There is an Interstate shop right next to work. They are half price. $60 each.
My troller is 24v. You sure you want a 12 volt with 2 batteries. If your already going to have 2 batteries you may as well go 24 volt troller.
Get a troller with a variable reostate switch for speed. Mine cerchunks from 1 2 3 4 5 settings. Ive seen them where they just turn like a volume knob. Thatd be the ticket b/c I always seem to want to slow down or speed up and the next number is too fast or too slow.
The diff amp chargers effect how long it takes to charge. More amps the faster the charge.
Good luck. Be safe.
https://www.amazon.com/gp/product/B003JSO1X2/ref=oh_aui_search_asin_title?ie=UTF8&psc=1You purchased this item on February 26, 2012.
Style: 3-Bank 30 Amp | View this order