Best House Battery at any cost?

[rwidman]

Originally Posted by Teknav

.......... To negate that factor, once and for all, a portable generator is recommended; despite its noise, gasoline requirement and possible wiring modification. ......

You forgot the fact that you might wake up dead one morning from CO poisoning.

[OrangeCrush]

I'm attaching a few pics. They're not the greatest images, but they give an idea of the limitations of my deck space. My dinghy lives on the foredeck, and there is barely room to walk around it as it is. I found a 75 watt solar panel for $150 that will fit perfectly on the sliding hatch cover. (ALEKO® 75W 75-Watt Monocrystalline Solar Panel - Amazon.com) If I keep the other two where they are now (only one is pictured), I will be up to 85 watts. I can probably find a slightly better one for that side spot, and bump up my capacity to 100 watts as I mentioned. As I said, the boom will be casting a shade one one panel or another most of the time, but I can try to minimize that as best I can.

So, I'm guessing there is a good reason for your recommendations, but what advantages does the $170 genasun controller have over a $30 sunforce one? They are both rated for roughly the same maximum wattage, well above what I will be generating.

Still not sure if all this is going to be worth the expense if I will probably need to end up getting a generator anyway...

[OrangeCrush]

I just read up on MPPT controllers and I now understand how the cheaper ones will be nowhere near as efficient. No real need to address this question now, thanks.

[OrangeCrush]

I guess this question is mostly directed to Maine Sail, since he is obviously the authority on this sort of thing, but any advice is appreciated.

If I am looking at the Duracell batteries that Sam's Club has to offer, it seems like I can choose from:

2 Deep Cycle Marine & RV 12v Batteries (105ah each)
2 12V GC12 Golf Cart Batteries (155ah each)
2 6V EGC2 Golf Cart Batteries (230ah each)

If I hook up two 6V batteries in series, do I have 230ah at 12V? It seems like the using two GC12s would have the best overall capacity (310ah together) out of these choices, even if they're not quite the best cost per amp hour. I don't have any issues with vertical clearance in my battery compartment. Are there any other factors to consider when using 6Vs or any overall advantages to the 12V batteries?

By the way, I ended up going with the solar option over the generator. I got the controller and the monitor that you recommended, a 75 watt panel and a 30 watt panel to add to my 2 existing 5 watt panels. We'll see how it works out!

Thanks,

Jack

[Dockhead]

Originally Posted by OrangeCrush

I guess this question is mostly directed to Maine Sail, since he is obviously the authority on this sort of thing, but any advice is appreciated.

If I am looking at the Duracell batteries that Sam's Club has to offer, it seems like I can choose from:

2 Deep Cycle Marine & RV 12v Batteries (105ah each)
2 12V GC12 Golf Cart Batteries (155ah each)
2 6V EGC2 Golf Cart Batteries (230ah each)

If I hook up two 6V batteries in series, do I have 230ah at 12V? It seems like the using two GC12s would have the best overall capacity (310ah together) out of these choices, even if they're not quite the best cost per amp hour. I don't have any issues with vertical clearance in my battery compartment. Are there any other factors to consider when using 6Vs or any overall advantages to the 12V batteries?

By the way, I ended up going with the solar option over the generator. I got the controller and the monitor that you recommended, a 75 watt panel and a 30 watt panel to add to my 2 existing 5 watt panels. We'll see how it works out!

Thanks,

Jack

I think you already got that advice -- 6v golf cart batts, hands down. Yes, two 230 amp/h 6v batts in series will give you 230 amp/h at 12v nominal. You will have half the number of cells compared to using 2x 12v batts, so will stay in that much better balance, plus the cells will be much more robust. If it fits, no question about its being better.

Even better four of them to make 460 amp/hours, although that will possibly be overkill in your case with no refrigeration and good power budget.

[OrangeCrush]

You're right, sorry for the repeat question but I guess I had a mental block about the 6v setup.

So the benefit of having fewer cells in the EGC2 pair would outweight the greater overall capacity of the GC12s?

[Dockhead]

Originally Posted by OrangeCrush

You're right, sorry for the repeat question but I guess I had a mental block about the 6v setup.

So the benefit of having fewer cells in the EGC2 pair would outweight the greater overall capacity of the GC12s?

It depends on how desperately you need that extra capacity.

If your solar production exceeds your consumption, AND if your battery capacity gets you through nights and overcast days, then you'll be fine. Otherwise, you will need more capacity, in which case I would go straight to the four 6v batteries.

With no refrigeration and no heavy inverter use, with LED lighting and an LED anchor light, so most consumption is charging phones and computers, I would think that 230 amp/hours ought to be about enough, but I'm guessing here. You'll probably have to try it and see.

[Kettlewell]

I basically agree on going the golf cart 6V route, which is probably the best bang for the buck in deep cycle batteries. But in some boats (like mine) it is really hard to reconfigure your battery compartment to fit the golf carts in an arrangement that makes sense. My boat has molded in battery slots that perfectly fit the width and length of GP 31 12-volts, and holds them in place quite nicely. I'm on the sixth year of some 12-volt Interstate deep cyclers, which were not my first choice but were the only batteries available locally at a decent price when I needed some. Also, the 12 volts do have the advantage that if one goes bad you still have 12 volts from the other--this has happened to me and I have had to just grab any old 12-volt car battery to keep going, or limp along on one battery, but at least it was 12 volts. Of course, the 6-volt golf carts are less likely to die in the first place, and there are numerous places in Maine to purchase them.

[OrangeCrush]

Thanks for the useful info.

My battery trays are quite roomy (I currently use shims and straps to secure the batteries in place), so I don't think I'll have any problem getting the golf cart batteries to fit in there.

I think the only modification I will need to make is to rewire my battery switch so that "1" and "2" don't do anything but "1+2" connects to positive terminal of one of the batteries in series. When I wire up my new battery monitor I will just treat the two batteries in series as one big battery and hook up the shunt and leads according to the instructions. The same goes for the solar panels and controller, I suppose.

Yes, Dockhead, I'm hoping that will be enough amp hours, since it is roughly what I had up to this point, with the added durability of golf cart batteries and the added charging capabilities of 105 watts additional solar charging.

Thanks again to everyone for the help!

[OrangeCrush]

So, I installed 2 new panels, wired them all up in parallel, installed the controller and battery monitor and everything is working! (see picture) I really appreciate all the help I got on this thread. Thanks!

I only had one opportunity to test the output of the panels. It was around 6pm and overcast, but it was still generating around 1.8 amps. This was equivalent to the power draw from the stereo, gps, and depth sounder together. I would assume that in full sun, and earlier in the day, that this would probably double. Not too shabby for my needs, although I'm not sure how it compares to what 115 watts of panels should be producing.

I do have one question, though. In the genasun controller manual, it says that multiple panels should be installed with a blocking diode on each panel, which I have not yet done. Other people have told me this is not necessary. My understanding is that this could help prevent the current being dumped from a sunnier panel into a shadier panel rather than into the battery (It is quite likely that one panel or another finds itself in the shade of the boom at any given moment). It also says the panels should be identical models and facing in the same direction or I should use separate controllers for each one. This last piece of advice is not feasible with my remaining budget and spacial constraints, so hopefully it's not critical.

So, should I install blocking diodes on each panel, or be happy with the output I'm getting already? Are there any other factors I'm not considering here?

Thanks again!

Jack

[hellosailor]

Jack-
There may already be blocking diodes in your panels, internally. Check with the maker. If not, then yes. you might want to add them.