The one pack idea is fine near home, but the charging panel execution in case of poor weather is not so good, as in -- say half the deck area needs to be covered - to recharge in an eight hour period, like over night. Any time winds get even close to say local lake or coast guard small craft warning, the need for power plus the windage could be a disaster. So, the deck area is the safest cell array mounting, but a canopy is the way to charge in a reasonable time in some areas. This applies to power boats obviously, if you can sail, the whole picture changes. Having one big pack is similar to a car cruise through death valley, without knowing if the gas stations are open that month, or having an extra can available.
My loaded cruise draw is 10 amps, less if no wind or tides, for safety 60 amp hours available. So I get six to seven hours max. but constant draw is not great on the pack either, in use I'm looking to be back at that dock around six hours, or read the meter to get home before the wind stops me, and my motor is water cooled or I wouldn't trust that to work.
The power cruiser (no sails) solution is to figure two banks, A and B, then you need to start back before the first one is dead. While the A pack rests, some small solar charge will help to keep it useable in case B (on line ) encounters wind, waves or whatever. Pack A can be brought back on line for emergency, and neither will be as deeply discharged, so both banks last longer. Of course that is 8 batteries for a 48 volt system, so maybe smaller batteries would work. I use 27 series instead of the bigger commercial sizes, good value, I pay $75. each, replaced the pack after three years, even though tested good. Sometimes too much high $$ tech. just stops the whole project, I like A $300. battery pack, replace it as a scheduled deal.
That seems better than watching one battery "smoke out" and the whole boat system fail, as my first pack did. No fun to be 100 yards from shore with rising wind and fuses blowing repeatedly. Auto reset motor fuse worked (whew !!) or we would have drifted to a lea shore beach, without power. Being stuck 30 yards out on a shallow bar, no fun. Now I at least carry a 50 lb thrust 12 volt Minn Kota on a different battery, as a safety. One really good thing about "gassies" is the extra gas can -- when you need it.
1 – Electric 17' cabin ( removable) cruiser 48v. Evinrude OB conversion
2 – Minn Kota 55 lb. in a well, on a 16' Sharpie sail boat with a centerboard
3 – Built in hull tunnel drive, with electric 12 v. drive in a foldable 11' Louisiana Pirogue
4 – Inflatable 9' with another Minn Kota on an outboard adjustable bracket keeping the interior space clearer.
Just some observations, your opinion is what you choose to live by, as do I ---------- Cal 1 – 2 – 3 – are all my own designs, over 15 years of fun.
Sent: Sunday, May 10, 2015 5:19 AM
Subject: [Electric Boats] Re: Solar panels vs batteries
On another note, if a smaller battery bank will accomplish all that you need for the time use your boat, each time you use it,then it makes no sense to increase it.
If you want to be as green as possible, and want to use your boat more often, go ahead and get more solar panels.
eric SV
Meander
---In electricboats@yahoogroups.com, <sstuller@...> wrote :
A 130 watt solar panel will give you about 500 watt-hours per day i.e. annual daily average. That's about 15 KWH per month. If you have a two KWH battery bank and double its' capacity you will have a four KWH bank. Adding another 130 watt panel will increase your monthly output to 30 KWH. Clearly adding solar panels is far more effective than increasing the size of your battery bank. So why is there so much obsession with batteries when the real power comes from the panels. Thanks.
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Posted by: "cal" <h20dragon@centurytel.net>
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