What's Needed

[JusDreaming]

Well we just got back from the annual four months in the Bahamas. And the new solar system worked well, but it is only just keeping up with our usage. It is not building up any reserve amps in the banks. So my question to the astute members here is: do I need more amp hours/more batteries,( I have about 350 AH currently), or do I need more solar panels or possibly a wind gen?

[YourOldNemesis]

You've just told us that (energy in) = (energy out) and you're asking if you need more space to store it?

[JusDreaming]

Originally Posted by YourOldNemesis

You've just told us that (energy in) = (energy out) and you're asking if you need more space to store it?

the rpoblem is when there is a day with little or no sun the banks are drawn down

[YourOldNemesis]

After a day of no sun, does it take sun all day the next day to get back to 100% or do you reach 100% by lunch time and then have to throw the extra electricity overboard through the afternoon?

[skipmac]

Well, without more specifics, the simple answer is you need more charge in. Adding another battery just adds more demand on the charging system.

However, the answer can depend on your system and the charge/discharge limits you are working with. What charge level are you reaching with your current system? Are you trying to recharge your batteries back to 100% with your current charging system or are you working from 50% to 80% range? Do you have an MPPT controller?

[JusDreaming]

Originally Posted by skipmac

Well, without more specifics, the simple answer is you need more charge in. Adding another battery just adds more demand on the charging system.

However, the answer can depend on your system and the charge/discharge limits you are working with. What charge level are you reaching with your current system? Are you trying to recharge your batteries back to 100% with your current charging system or are you working from 50% to 80% range? Do you have an MPPT controller?

I would like to get back to 100% if possible, and it takes about all day to get the power back. ANd yes we have an MPPT controller

[BubbleHeadMd]

Then the answer is that you need more charging capacity, not more storage. Add a panel.

[bloodhunter]

Dreamin,
Since your problem seems to be days without sun, Don't think adding and extra panel will do you much good unless you add more batteries to store the surplus electricity produced when the sun does shine.
You might do better with a wind generator, as the wind is generally pretty reliable in the Caribbean

[MarkJ]

JusDreaming,

I'm not sure if you rather brief posts about your problem need to be expanded fully so the experts here can crap on for ages

I am indeed an expert on doing things the cheap and wrong method that works fine & dandy.

We have 300ah of old telecomunications rack batteries that were thrown out about 6 years ago, left in a house uncharged for 5 years and given to us 12 months ago. Not only are they not deep cycle they can't do anything on a boat except sink.

They are, however working fine

Our solar panels are totally unregulated and we have 2 x 120 watts and I have to drop one panel most of the time to hide it from the sun.

Yes, a cloudy day could stuff you about.

But if you are reaching near 100% on sunny days then you have hit an amazing situation: being able to charge your batteries the last 5% which is very difficult and electricity consuming.

I think you could try a few things before you did your friends in the face with a wind generator (I call them Enemy Makers. Go anchor near a friend and the friend will be no longer!)

· Do you have a fridge or freezer on?
· Are you heading to the Caribbean or back to ice bound USA?
· Do you leave your instruments etc on at anchor?

Fridge and Freezer. Can you turn the thermostat down and still keep the units going? A fridge only needs to be 4 deg Celsius, NOT zero. the difference is huge. A freezer at home is -18Deg Celsius but on a boat only needs to be (not hotter than) -5. Some are set so they are -18 at their warmest. Being able to turn your freezer down so it works for a few hours less per day will save you more amps than anything! fridge is second.

If you are heading to the tropics you will get more amps into the solar panels and then you will definitly have extra amps Yay!

Most boats I get on are wasting power like nufin on earth! At anchor who needs the VHF on 24/7? or the Wind instruments? Or, worst the chartplotter? Go right through your boat and check for waste. Just one halogen light somewwhere, like the anchor light can wreck your power plan.

After all that then start looking at buying a new battery to put in your house bank. 450AH is a substantial size bank and any great sun days will save you your amps. On the other days, or if your pannels dont quite cope you can run the engine for an hour every couple days

These are just my ideas if I was in your situation. But to get proper help from the folks here you need to write a full detailed post so we are not just stabbing in the dark


Mark

[slomotion]

When we were cruising the Bahamas/Caribbean, I don't think our batteries were ever charged to 100% unless we were doing a lot of motoring. If your normal use in your normal cruising grounds frequently leaves you close to 50%, then increasing battery capacity might be a good idea. But, as others have said the primary issue is charging.

Since your annual 4 months in the Bahamas are winter and early spring, I think the obvious answer is a wind generator. Unless you are very far south, those months will give you frequent cloudy but windy days as continental cold fronts move through. Most islands are low lying and many Bahamian anchorages shelter you from waves but not so much from winds. A good wind generator could make a big difference.

[cdennyb]

having more amp capacity and only drawing them down to >80% not the 50% as noted above will increase the usable life of those batteries immensely. Adding a panel to get them back up quicker is ideal, who cares if you don't need the extra 5 hours a day of available sun charging... go turn the music up and make that amp suck those extra electrons. LoL

[S/V Illusion]

Increasing the battery bank is futile unless you have a way to adequately recharge. Think of a water bucket as a metaphor for the batteries - start out full and continually draw down with only some refilling and eventually you end up with an empty bucket.

In any scenario of battery bank size, you can't escape the conclusion you need more charging capacity.

[CharlieJ]

Just a fine point to consider; the Bahamas are not in, or near, the Caribbean and are not considered tropical.

Charlie

[GordMay]

Originally Posted by CharlieJ

Just a fine point to consider; the Bahamas are not in, or near, the Caribbean and are not considered tropical.
Charlie

Roughly 1/4 the Bahamas islands are in the “tropical” (between 23.5 degrees latitude North & South) zone, and they are politically considered Caribbean, though not geographically so.

The “Tropics” are bounded by the Tropics of Cancer on the north, and Capricorn on the south. The Tropic of Cancer (23.5 deg. N) runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China.

[MarkJ]

Originally Posted by GordMay

Roughly 1/4 the Bahamas islands are in the “tropical” (between 23.5 degrees latitude North & South) zone, .

Hi Gord and Charlie,

How much more power do you think you get per degree of latitude? Per 10 degrees may bee better.

I havent made a study, but our 2x120watts solar pannels have topped out at about 13 amps in the tropics, now at 40 degrees north they pull in a bit over 5-7 but not for too many hours.

It would be interesting to know for folks setting up their boats in the high latitued to come to the butter melting area.

Also batteries are more efficient in warmer areas too.


Mark