Author Topic: Solar panels  (Read 1394 times)

Offline Alex H.

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Solar panels
« on: May 01, 2013, 04:04:26 PM »
I assume the easiest way to charge the battery on the Suncat is to have a solar panel near the bow when the boat is not being used, run the wires through the anchor locker and to the battery , although I have a Tohatsu 6hp sail pro with the alternator, the distance and the wiring required seems no to be worth it. Any thoughts/ guidance on solar panels? Make, location wiring tips etc? Would be greatly appreciated.

Offline skip1930

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Re: Solar panels
« Reply #1 on: May 01, 2013, 04:36:32 PM »
I have a solar panel on my CP-19. it sits on cane tips to assure that air circulates under the cell and the tips are glued to the glass/plastic square of the forward hatch and the wires snake in upon the closed hatch and down the compression post, under the vee birth and quarter birth on the starboard side to the battery box.

Every time I talk about my solar panel I get a hand slapped from the others here because I'm not sure if my panel is diode protected, nor protected from over charging the wet cell battery and boiling the water out of it. I don't care anymore. So I check every once in a while to see that water/electrolyte is covering all six cells. If not I add some Reverse Osmosis water from my home tap.

The cell only puts out 300 milliamps DC. in bright sunlight. This will not keep up with electrical loads if the loads are continual.

I shouldn't even answered this post. Just waiting for the slap on the hand.

Take the red and black wires, [ bigger then you think they need to be, may be 14 ga? ] and clamp the two ends into a garage vice. Then the other two into a drill motor. Twist these together nice and tight while pulling back on the drill motor, but still walking forward as the wires become shorter. Makes a nice tight wiring loom and because its twisted together juice flowing through the twisted wires will not influence the compass.

skip.

« Last Edit: May 01, 2013, 04:44:34 PM by skip1930 »

Offline tmorgan

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Re: Solar panels
« Reply #2 on: May 01, 2013, 04:43:35 PM »
I have a portable panel I store on the boat and put on the deck when I'm at a dock or at anchor.  It came with a cable that plugs into the panel and into a plug that attaches to the battery.  I just lead  the wire through the hatch to the battery. I charge the battery in the spring and the panel keeps it charged during the season.  Of course it depends on what electrical devices one uses.  I just power cabin lights, nav lights (rarely) and an LED anchor light.

Offline Shawn

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Re: Solar panels
« Reply #3 on: May 01, 2013, 05:08:37 PM »
Alex,

How much battery power are you planning on using and how big of a solar panel are you thinking of buying? A small trickle charger won't be enough to really recharge your battery.

For a solar panel you should also include a charge controller. These will prevent the panel from overcharging your battery and killing it. Good charge controllers can be had for $25ish dollars. Cheap investment to protect a $100+ battery. On my 23 I have a 40 watt panel mounted on the hatch feeding a charge controller and a group 27 deep cycle battery. I run an autopilot, gps, vhf, fan, pressurized water and lighting. All my lighting is LED which saves a huge amount of power. The battery is recharged by solar.


The SailPro alternator can be handy but really only if you motor for longer periods of time. If you are using it for 5 minutes in and 5 minutes out that won't give you much juice. On the flip side if you are motoring for 8 hours at night with all lights on the alternator on the Tohatsu would be wonderful.

Shawn

Offline Alex H.

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Re: Solar panels
« Reply #4 on: May 03, 2013, 10:32:11 AM »
My access to the ICW is 45 minutes from my dock and another 30 to the port Everglades inlet, so in/out I will motor about 3 hours which should top off my battery. I'm just not crazy about running a long wire to the battery across the cockpit and cabin. My needs are mainly for the nag lights as I'm returning home. I thought trickle charging while docked was the better way to go.?

Offline Shawn

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Re: Solar panels
« Reply #5 on: May 03, 2013, 06:46:20 PM »
"I will motor about 3 hours which should top off my battery."

Yes, the Tohatsu is rated to 5amps of output (about 60w) but that is likely at full throttle. At cruising speed you will get something less than that. I haven't measured what mine puts out while cruising but 2-4 amps (24 to 48 watts) is probably a decent guess.

"I'm just not crazy about running a long wire to the battery across the cockpit and cabin."

Run the cable inside the boat and put a quick release near the engine if you take the engine off the mount when you trailer it.

" I thought trickle charging while docked was the better way to go.?"

Not typically. A discharged battery should be recharged as soon as possible and, within reason, as quickly as possible. A small portable solar panel will take a *long* time to replenish a discharged battery. The Tohatsu would recharge it much quicker and that is better for the life of the battery.

Battery capacity is measured in amp hours… literally how many hours it can output 1 amp. A deep cycle can be discharged to about 50% of capacity and not suffer damage if it is recharged at a reasonable rate. (Starting batteries shouldn't go below 90% discharge) Say you have a 100amp/hr batter… that gives you 50amp/hours of actual capacity. 1 amp output for 50 hours, 50 amps output for 1 hour or any sort of combination there.

You can estimate your needs by looking at your load and how much time you will use it to get an idea on how many amp hours you will use.

As an example…. if you still have incandescent navigation or interior lights they are energy hogs. You could be easily pulling 3 amps from the battery with those lights on. Leave the lights on for 3 hours and you have used 9 amp hours of capacity.

How to recharge those 9 amp hours?

Say you are running the Tohatsu and it is outputting 3 amps and you run the engine for 3 hours you have recharged the battery. If you really only have the lights on while running the engine you are basically at a wash… the engine is supplying the power for the load and you are not charging or dicharging the battery.

Now take the case of recharging with a small portable solar panel. West Marine has a 5w model that is 14"W x 13H". 5w is about 0.4 amps of output… in full sun. It will take almost 23 hours of full output from the solar panel to recharge the battery.  On a sunny day you get full output from the panel for 5ish hours of the day, the rest of the day the output is lower. To recharge the battery could take half the week (or more if it is cloudy) and the charging isn't constant due to day/night.

A bigger panel would handle this much quicker/easier but then it needs to be permanently mounted. The panel I use would recharge the battery in about 3 hours but it is considerably larger.

The other option to getting away with the smaller battery is to make your draw lower. LED lights could use 0.5 amps or less which would mean the 5w solar could recharge it much easier.

Shawn

Offline frank

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Re: Solar panels
« Reply #6 on: May 04, 2013, 08:35:46 AM »
After a ton of searching years ago...Sunelectric has the best buys on panels. I have used them on my cottage, cabin and boats. They have a 40watt panel that will fit in a cockpit locker. You would definately need a charge controller. They may have smaller panels as well. Sometimes it is easier to call them as not everything is listed online. You will find their pricing amazing! Sunelectric was in the solar biz WAY before it got popular. They "were country, when country wasn't cool"   ;D ;) :D

http://www.sunelec.com/

her's a 20 watt panel for an example   http://www.sunelec.com/sun-20-watt-12-volt-solar-panel-176-vmp-p-843.html
« Last Edit: May 04, 2013, 08:42:04 AM by frank »
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Offline MacGyver

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Re: Solar panels
« Reply #7 on: May 04, 2013, 09:03:49 AM »
I made a video about twisting wires on here somewhere..... I do that all the time on radio installs in boats and lights, etc.
Instruments usually have a jacketed setup with all the wires in it.

As far as solar panels I know nothing really on em, and have been reading as much as I can here and elsewhere. Might add one to my boat as sitting waiting on the digital charger to charge it when I am here is sometimes not conducive to what I planned to do that day.
The charger on a motor if it is a alternator should reach peak right at fast idle. A Generator like on a diesel engine needs the throttle amped up as it generates based on speed.
Maybe I am wrong......but that is how it works on the engines I work on as far as what I have tested. Different engines have either the alternator or generator and I doubt the industry really puts the actual name out there.

On a J29 my boss insisted that the juice to start the boat would take around 3 to 5 hours to replenish...... so I had to ask during testing why in 20 minutes the batteries were full...........and why overnight the batteries were still full.....overnight gave them time to settle.
When charging a battery, a ten amp charger here at work has countless time from near completely dead battery state charged a battery to full charge in a little over an hour.......according toy boss that isn't possible....

Not to throw doubt into the data here from the others, and I know there is solid answers out there to explain this, and I am not trying to start arguments, etc...... but if I were you, maybe just get a panel sized to what you would like to see in your boat. Then maybe once a month use a charger that is automatic but that you can watch and top her off.
Using LED bulbs is great idea, will make lower demand and faster charging which means more sailing :)

Mac
Former Harbor Master/Boat Tech, Certified in West System, Interlux, and Harken products.
Works on ALL aspects of the sailboat, 14 years experience.
"I wanted freedom, open air and adventure. I found it on the sea."
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Offline skip1930

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Re: Solar panels
« Reply #8 on: May 04, 2013, 09:42:44 AM »
" Different engines have either the alternator or generator and I doubt the industry really puts the actual name out there.  "

No name, but here at the aeroport, when a new alternator or generator for say the New Holland tractor or even a Cessna is needed, a test is done over at our NAPA store and a readout is printed showing the 'sign wave' [what ever that is], the amps, and voltage at various rpm's, and the amount of hp needed to produce those numbers. Sheaves and/or pulleys can be properly sized if need be if we change motors or what ever....The tag and print-out for the alternator or generator stays on file so exact replacements can be had...or tweaked to 'as it first was'.

Boy do we keep records...!! It's public money and we watch your pennies. Honest! skip.

Offline Shawn

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Re: Solar panels
« Reply #9 on: May 04, 2013, 12:26:33 PM »
"The charger on a motor if it is a alternator should reach peak right at fast idle. A Generator like on a diesel engine needs the throttle amped up as it generates based on speed."

Did you test output voltage or output current? Alternators have voltage regulators on them so that they will output 12.8v (or whatever) pretty quickly. If you just measured voltage it would look the same as say 1500rpm and 5000rpm. However, if you check current output you will see the alternator is putting out more current at 5000rpm compared to 1500 rpm.

" a ten amp charger here at work has countless time from near completely dead battery state charged a battery to full charge in a little over an hour.......according toy boss that isn't possible...."

Is that a starting battery or a deep cycle? A starting battery discharged 10% (about the limit of what it should be discharged) is less than 10 amp hours of capacity.. a 10 amp battery charger would charge that back up to full in about an hour. For a deep cycle it would take much longer to recharge a 'fully discharged' (50% capacity) battery.

Shawn