Lets's talk multiple battery setups. (3+)

[cab13367]

I'm coming to conclusion that amp/hours can't be argued, and 2 6v are simply the better way to go (size permiting).

How so? You quoted that a pair of 6V golf cart batteries provide 180-220 AH whereas a pair of Group 27 marine deep cycle batteries provide 230 AH (at least the ones at costco do). And they are smaller than the 6V batts.

Also, I think you are going to have to upgrade to the ProSport 20. As David has pointed out, you need a charger with an output of 10-13% of your total battery AH in order to desulfate the batteries during charging.

I currently have a two battery set up (one starting and one stereo) but fortunately, I bought the ProSport 20 in case I added a third battery in the future. Sure enough, I went from two amps to three at the end of last season so I am going to add a second stereo battery this winter. With that, my charger will be below the 10-13% recommended output for the 230AH worth of stereo batteries (not even counting the starting battery) but as long as I don't discharge them too deeply, I think I will be okay. At David's suggestion, I will probably add a switch to the starting battery charger lead so I can take it off line when needed and direct all 20 amps to the stereo bank.

Al

[cab13367]

FYI, below is a shot of my current two battery set up.



And here is a better shot of my Blue Sea ACR set up, before I added the on board charger and the third amp.

[dusty2221]

How so? You quoted that a pair of 6V golf cart batteries provide 180-220 AH whereas a pair of Group 27 marine deep cycle batteries provide 230 AH (at least the ones at costco do). And they are smaller than the 6V batts.

Also, I think you are going to have to upgrade to the ProSport 20. As David has pointed out, you need a charger with an output of 10-13% of your total battery AH in order to desulfate the batteries during charging.

I currently have a two battery set up (one starting and one stereo) but fortunately, I bought the ProSport 20 in case I added a third battery in the future. Sure enough, I went from two amps to three at the end of last season so I am going to add a second stereo battery this winter. With that, my charger will be below the 10-13% recommended output for the 230AH worth of stereo batteries (not even counting the starting battery) but as long as I don't discharge them too deeply, I think I will be okay. At David's suggestion, I will probably add a switch to the starting battery charger lead so I can take it off line when needed and direct all 20 amps to the stereo bank.

Al

Well, I guess i was basing that assumption on what the quote I added showed. I must have breezed past the 12v rating you mentioned, or read and and didn't "read" it. Ha

As far as the 10-13% recommended output, does the fact that the charger would have a lower output than that really make a difference in charging aside from a longer charge time? So rather than my Pro12 charging the 2 current (1 crank, 1 stereo) in say 6 hours, if hooked to 3 as mentioned earlier, it would still charge, however, the time it took would greatly increase if they were completely depleted, but they would be charged, conditioned and maintained properly?

I hope all that makes sense.

Also, I am taking it as you have the Pro20 dual bank rather than the 3 bank?

[cab13367]

Well, I guess i was basing that assumption on what the quote I added showed. I must have breezed past the 12v rating you mentioned, or read and and didn't "read" it. Ha

As far as the 10-13% recommended output, does the fact that the charger would have a lower output than that really make a difference in charging aside from a longer charge time? So rather than my Pro12 charging the 2 current (1 crank, 1 stereo) in say 6 hours, if hooked to 3 as mentioned earlier, it would still charge, however, the time it took would greatly increase if they were completely depleted, but they would be charged, conditioned and maintained properly?

I hope all that makes sense.

Also, I am taking it as you have the Pro20 dual bank rather than the 3 bank?

I will try to do justice to David's explanation on the importance of having adequate current when charging batteries. A certain amoun of current (10-13% of the AH rating of the battery) is needed to chemically excite the batteries so that all the sulfates that stick to the lead plates when a battery dischages releases from the plates and goes back to the acid solution. If you don't have enough current, the sulfates will stick permanently to the lead plates and over time, your battery will have less and less reserve capacity.

Yes, I have the dual bank 20. The 3 bank is still 20 amps and since the two stereo batteries will be wired together as one bank, only a two bank charger is required.

[dusty2221]

Got it. Thanks.

So what we just boiled this whole thread down to is this:

1. 2 12v for stereo is an easier setup to work with, and with the costco batts will provide more a/h than the 2 6v

2. The Prosport12 will not excite 3 batteries if depleted badly enough

Conclusion: Like anything boat related, (ha) My simple quest to add 1 battery has now turned into

1. Two new 12v deep cycle batteries (on Davids recommendation on same age etc)
2. A new Higher output Charger, or different setup of existing, which there are three options for:
a) The Pro20 with a switch inline to bank one(starting) for dedicating the full 20 Capability of the Pro20a to the two stereo batts for those recharges after a long stereo day
b) A dual bank 30a charger, like the Guest 2633A that offers one bank with a 20a output and the second as a 10a output
c) Move existing Pro12 exclusively to the dual stereo batts and get a basic 1 bank charger for the house batt. Although, this route doesn't supply the needed amps in case of complete depletion and could end up allowing the lifespan to shorten since the 2 batts would only be getting a combined 12a

Have I narrowed it down to what you would agree with?

[EarmarkMarine]

Dusty, you can easily recover your investment in the ProSport, probably from someone on this forum who is in need.
Get an Intelli-Power 30 amp charger and a flushmount AC inlet that can be installed under the hatch next to the engine. This way all you have to do is fold back the cover and raise the hatch while standing on the trailer. You won't have to climb into the boat. The Intelli-Power 3-bank will function as a dual bank with two stereo batteries permanently wired in parallel or you can wire it as a 2-bank plus this charger has the ability to distribute its capacity based on the bank that is in need.

David
Earmark Marine

[KG's Supra24]

Or it is possible all of this is over thought out and you are fine with the 2 batteries you currently have bc I ran 4 amps all last year and had no issues.

just thought for simplicity sake. And if the battery goes dead then you have $$ you saved from not buying everything else discussed in above threads

GO HOGS!

[dusty2221]

Anything worth doing is worth over doing.

[sandm]

I think that every answer about this is going to be different. if your boat is in the party cove every weekend for hours on end, tons of led's that get used longterm every night and you hate digging into the batteries after every outing, then the charger and extra batteries would be something to highly consider. I have found that with a moderate system, 2 good deep cycle batteries, and occasional long play usage at moderate volume levels, the 2 battery system is good enough, and the onboard charger is really more of a convenience than a necessity(same thoughts as KG I believe)

do the research, put in what fits your needs and don't follow the sheep..

[cab13367]

sandm is correct - every situation is different. In my case, I started it out with two amps and two batteries (one stereo and one starting). Everything was fine until I went on a 4 day trip where I had no access to a power source. By the end of the second day, one of my amps went into protect because the stereo battery had run down (we do a fair amount of swimming and listening to tunes as I have a couple young kids). So we had no tunes for the next two days.

I did some research on battery chargers and decide I wanted an on board charger for the convenience of being to just plug it in when I get home every night and be assured that both batteries will be desulfated and ready to go the next time. Got good advise from David so went with the ProSport 20.

Now I've added a third amp and my system is now capable of 2050W RMS and for me, adding a second stereo battery is a relatively low investment - basically $69 for the batt, maybe $12 for a batt box, and a few dollars for short runs of cable. Also, my tow vehicle battery crapped out this winter so I threw the stereo battery in the truck as it was the right size, and since you should always start with two equal batteries when setting them up as a single bank, this is the perfect opportunity to upgrade to two stereo batts so I don't ever had to worry about running out of juice on the water again.

So that's how I got from point A to point B to point C.

Al