ProMariner ProSport 2Bank Charger

I'm looking to add a 2 bank charger to the boat. I just bought 2 brand new batteries and want to keep them up so hopefully they'll last a little longer.

I found this ProSport 8amp charger for $92.11, which fits my budget:
http://www.usaboatstore.com/ProMarin...m?feed=Froogle

Is it necessary for me to spend an extra $70-90 more for a 20 amp?

I keep my boat in storage literally less than a mile from my house on the lake. When I used to put it up and turn the manual charger on (2amp/trickle), I would leave it days at a time before remembering to go back and turn it off.

Am I right in thinking this 8Amp charger might be better for me since I rarely need it to be 100% charged for the next day. We usually go out one full day a week, maybe a half day on the next day, then in storage for 4 or 5 days...

Suggestions?

One size charger does not fit all. Don't follow people who say, 'I have this charger so I recommend the same.' The charger size should not be predicated on the recharge time. The correct charger selection should be based on a combination of a) the collective reserve capacity of your batteries, and b) your unique & individual usage habits, such as how deeply you discharge your stereo battery/bank on a regular basis.
If you have a total of two group 24 batteries and during periods at rest you only deplete the stereo battery to a minimal discharge, then a dual bank 8-amp charger is absolutely sufficient. With larger/more batteries and deeper discharges then you need a larger model.
A large part of this is whether you fit into the maintenance category or the need for stronger conditioning category.

Guess I could've added my batteries to the post... Small town not much selection, but I picked up 2 of these:
http://www.napaonline.com/Catalog/Ca...302_0399057337

I WAS running a stereo battery and a cranking battery with a perko switch to switch between running one battery or both when cranking, but when I upgraded my system last year I had to run my extra amp off my cranking battery so I guess basically now I have to run both batteries for audio with no designated cranking battery, which is why I'm wanting to pick up a 2 bank charger. I figure the main audio battery will still take most the damage so it will be nice to have a charger maintain the 2 batteries separately and get them both back to full when I plug it in...

Hope all that makes sense. Thanks for the info David

Okay, that looks like two group 24s which could be about 65 A/Hs each for a total of 130 A/Hs.
I would consider an 8 amp 2-bank charger to be a little more than maintenance. So this would be for moderate depletion like instrumentation/fishfinders/etc. No room to upgrade.
If you are running the stereo battery down to the minimum 12.0 volts at rest and you are not fully recharging the batteries on the trip back to the trailer (although the short term surface charge may incorrectly indicate you are) then I would invest in a 12 amp 2-bank charger. No room to upgrade.
A 20 amp charger is the largest that you could run safely with two group 24s. This will handle heavy depletion levels with the proper conditioning (desulphation) and give you some room to add another group 24 to the stereo bank for a grand total of three batteries.

Ok. I guess I don't really understand the differences of 8,12, 20. I thought it was just charging rates. And the main reason I was going to go with the cheaper 8amp is because I tend to only charge my batteries once a week (trickle charge for 2 days) then hit the lake for 1.5 days. We rarely sit still for more than a couple hours so the alternator keeps them up for the most part anyway while surfing and boarding.

I'm really only doing this out of convenience of being able to plug both batteries in to charge when were done for the wknd as opposed to only charging one at a time and having to come back mid week to jump in the boat and hook the charger up to the other battery....

So would the 8amp work for me or should I spend the extra money on a 12. I don't plan on running 3 batteries so 20 is not reasonable for me.

Thanks for all the help

Tgoody,

Think of the charger's amp capacity as HP and the size (Ah) of the battery as the load. More HP and the truck tows the load more efficiently. Higher amp output capacity from the charger, the more efficiently it recharges the battery(s).

If you have a small Ah battery setup and rarely run the stereo with the engine off, then a smaller amp charger will be fine to maintain the batteries. if you have a high amp draw stereo, a large Ah battery bank and spend hours on the weekend anchored playing the tunes. You will run that battery bank down, thus giving your charger a heavy load to recharge. This takes more amp then the 1st scenario.

💥BOOM💥
I see what you did there....
Thanks for breaking that down.
Muchas Gracias Senors!
Ill grab me a 12Amp 2 bank charger and call it good! We'll never drain these 2 batteries, so we should be good!!!!

Famous last words.... 😳

tgoody,
From what you have stated, the 12 amp model does sound best.
It's not the recharge time that's of concern.
It is a matter of the size of the reserves PLUS the depth of typical discharge. It's a combination of these two factors. Capacity AND usage.
Batteries can be brought back up to full charge and maintained with very little current capacity. But deep cycle batteries that are regularly depleted to a low level tend to sulphate, which means the acid solution separates and particles attach to the lead plates. Eventually this can't be reversed. It's like clogged arteries. And this accelerates the point at which a battery will no longer accept a charge....meaning when it's done. So it takes an appropriate amount of charging capacity to chemically excite and exercise the battery. This improves short term performance and long term lifespan. On the other hand, you do not want to over-charge and over-heat a battery. That's why a charger should be unique to your needs.