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post #8 of Old 12-10-2012
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Re: Updating electrical system

Regarding solar panel selection - throw away the idea of a 60 - 90 watt panel. That's fine for a short weekend but will only make you 30 -40 ah of charge a day. For most folks that's like camping, it won't support even a small 12v refridge unit.
Figure where you can hang the panel(s) (arch, davits, bimini, where ever) - then go for the largest panels you can fit there. 300w+ panels are out there - and they will fit a davit with a little thought.

Do spend the money for a MPPT controller, they really do provide an up to 35% increase in amps to the battery. Outback's are good and reasonable in price (still expensive though)..

Measure out your current battery bank space - good large capacity 6v GC batteries are taller than even Group 31 12v batteries. A pair of Trojan 145's will give you 290amp hours in a smaller deck footprint than a pair of Group 31's, but you have to have the height or it's a moot point. The truly important part is to get as much as you can given the footprint you have to put them in. If three 12v's fit and yield greater capacity than only 2 6v's that fit it's a no brain-er. Stick with lead acid unless you are 100% certain you can get AGM's up to 100% of charge at least monthly.

Find anywhere you can near the engine where it is coolish and put in the largest 12v deep cycle (you heard me right, not a starter). That's your back up and normal starting battery. Charge both the house and starter through an ACR.
Save the 20 amp 110v charger for those infrequent days at the dock - after all when you are there you'll have at least a day so up sizing that is a low priority.

After hauling in the anchor on a 39 footer a couple of times you'll start looking at a windlass (or a chiropractor), after sitting in the cockpit a couple evenings watching the sunset with a warm beer you'll be looking at a good fridge that makes ice.

The first time you are up the mast swap out that power drain we call an anchor light for a LED version. The old ones draw 1.2 ah or more and can suck a battery dry while you sleep.
Don't forget to add a good battery monitor to the mix (Victron BMV 602s for example). Hard to know what's going on without one.

You can always live frugal once you've installed the luxury, but not the other way around.

Lessons learned are opportunities earned.
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