DIY onboard charger/ or cheap on board charger

[Strahm]

I have an old boat, and i would like to get an on board charger, but i dont want to spend a lot of money. my question is, is there a cheap, or diy way to make/ install something to be able to keep my three batteries fully charged.
currently i dont have very good batteries, and i plan on buying new ones before spring, so i want them to last as long as possible.

what is my cheapest option, to keep my batteries charged correctly?

[wannabe fisherman]

in the long run it's cheaper to go ahead and get a good multi-bank charger in the first place. if you get a new-er boat then you can take it out of the old one.
Don't ask me how I know!! also check batteries for water every now and then unless they're sealed.

[Strahm]

thats the kind of reply i thought i would get.
so what multi bank charger should i get?
id like to stay cheap as possible but i know usually cheaper is worse quality.
i have a 24 volt trolling motor, and one starting battery so i think i should get a 3 bank charger, i know some guys dont use a bank for the starting battery but, sinc ei have an older engine there are some days that it takes a lot of cranking to get started so id like to charge the starting battery just as easily as the two trolling motor batteries.

so in short what on board charger should i get that is on the cheaper side?

[Barnacle Bill]

These are on sale at Cabela's right now and I've used one for years. Cabela's: Cabela's Advanced Anglers ProSport II On-Board Marine Battery Chargers Products

[Strahm]

im currently looking at this battery charger
Products :: Battery Chargers :: ProMite 5/5/3
its states under volts 12/24/24 + eng

my question is 1. what does the eng part mean?
and since it is 12/24/24 does this mean that i could technically hook up 5 batteries? (since a battery is 12 volts)

if that is true couldnt i get away with a 2 bank charger and hook it to 3 batteries.
i dont think this is right but the 12/24/24 part is confusing me

[CatFan]

im currently looking at this battery charger
Products :: Battery Chargers :: ProMite 5/5/3
its states under volts 12/24/24 + eng

my question is 1. what does the eng part mean?
and since it is 12/24/24 does this mean that i could technically hook up 5 batteries? (since a battery is 12 volts)

if that is true couldnt i get away with a 2 bank charger and hook it to 3 batteries.
i dont think this is right but the 12/24/24 part is confusing me

What they mean is that the third bank is low current (3A), which isn't suitable for a TM battery which is typically more deeply discharged. It means it can do a 12 or 24 TM setup plus the cranking battery.

[Strahm]

ok thanks that clears it up for me. sorry for the novice questions, i just havent been around boats very much, and am just getting into it.
i think im set on how to pick out a battery charger, now i just need the money to get one, and money to get three batteries this isnt going to be cheap

[wrs75]

Cabela's: Cabela's Advanced Anglers ProSport II On-Board Marine Battery Chargers

i have the three bank and can't complain, it is a lot more convienient to just plug the cord in then get battery charger out and hook up. especially if you travel any with boat.

[wannabe fisherman]

The Pro Mite is the one I have and it does the job for me, but then I'm not out every day pushing hard on the troller. I like the fact that when any battery comes to full charge it will redirect the current to another one that needs it. When all batteries are full it will maintain the charge at a safe level. With any charger keep an eye on the water level unless they are sealed. If they need water used distilled.

[Barnacle Bill]

If your charging circuit in the motor is in good shape then the starting battery rarely needs much charging. So I guess they made it that way to keep the price down. No reason why it shouldn't work just fine.