Solar Battery Charger

[Wobegon]

Has anyone had experience with using portable 20Watt solar chargers on their boat.  I am considering adding one to the boat to allow me to trickle charge the batteries during the day while on the hook.  This would only be for the occasional long weekend out and about, as we don't do any extended cruises more than a week at a time.  I have seen the portable ones that simply plug into the cigarette lighters and are used as a trickle charger.  I just want to do power maintenance to offset the drain from my refrigeration and to eliminate having to run the engine so much.   I have two group 27s for the house bank and one group 24 for the starting battery.

[SeaFever]

I too am interested to know from others on their experience of using such chargers on their batteries.

I have 2x group 27 batteries and I had connected such a charger (that I got from Costco) to one of my batteries and left it on the boat. My experience was that the charger did not do much anything and the battery did not have much juice when I came back to use it. Having said that, I found after wards that that battery was done for and I had to replace it. So my experience may be on account of the battery in question being bad. Don't know. I have not tried the solar charger after replacing the battery since I got a good 3-bank battery charger and connected it permanently. I turn on shore power whenever I need to start charging the batteries. Note: I don't live-aboard.

[Ron Hill]

Wo : I have two - 20W solar panels that will just keep the fridge "at bay" at hi noon.  Mine plug into a cigarette lighter receptacles.
The fridge uses (24/7) about 3.5 amps per hr, so you do the math.

[Lance Jones]

I'm with Ron. I have Two 20 watt panels that trickle into my system. With two, I keep up with one fridge. Problem is, I have a freezer too. I'm adding two 40 watt panels to my two 20 watts currently installed.

[Stu Jackson]

Let's get real:  a 20W solar panel provides "X" amps input per day.  The fridge draws 5 A when running on a 50% duty cycle and 60 AH per day (24 hours).  There is no way that small a solar panel is gonna do much at all to keep up with a fridge!  All they are good for is offsetting the inherent drain of wet cell batteries when you leave your boat during the week - unplugged.  

For Woebegon's intended use, they are excellent, as long as he pretty much fully charges his house bank before he leaves.

[sailingdream]

Me being in the great white north and having my 150W panels, no way can it keep the batteries topped off. With the reffer running only and no lights.

[Rick Johnson]

Down here in sunny Texas, 180 watts worth of solar panels keeps up with my Cold Blue refrigerator with no problem.  Always nice to have cold beer waiting at the boat. Especially now that it's hitting 90 degrees outside and the lake water is the perfect temp for swimming.. 

Cheers,

Rick

[waterdog]

400 Watts keeps up nicely with refridgeration loads!   

[SeaFever]

Wobegon,

Your original question was on your potential use of the 20W solar chargers. Hopefully you got an idea from the above posts on what the 20W charger can do for you. Not sure if you were planning on upgrading your project to larger solar panels. With respect to the 20W charger, here is what I infer: If you have good batteries and all you need is keep them topped up to counter the trickle discharge and low level amp usage, the 20W charges may help you. If your batteries are not up to snuff and you need serious charging, good luck with the 20W charger, they is not going to help you much. Your alternatives are, getting a larger solar charger or, investing in a good battery charger to be connected to shore power (which you may already have). As can be seen from the above replies, the size of the solar panel you need will depend on your rate of consumption, among other things.

[Lance Jones]

One question to add to this discussion...
Does anyone have a recommended solar regulator for a 4 solar panel system?

[Wobegon]

Thank you for the comments.  My battery bank is recently upgraded and brand new.  I just want to be able to top batteries, or keep up as best I can with the drain on the batteries when on the hook.  At the dock I have a great charger that does the job, I just want to have something to keep me from having to run the engine more than I have too...again just weekend sails out to the Lake Erie Islands.  I don't want to invest in the larger solar panels as they are not needed under our conditions. I will give it a shot and let everyone know.

[waterdog]

One question to add to this discussion...
Does anyone have a recommended solar regulator for a 4 solar panel system?

Regulators are based on the total power of the panels rather than the number of panels.   You will need to know both your voltage and your current.  Get a charge controller that will allow you to do all of your panels in series with MPPT.   You are far less vulnerable to Pelican poop and shading.   You can also use much smaller cabling with the higher voltage / lower current.   

I highly recommend Blue Sky 3024i.   Very simple to configure.   Flaweless performance. 

[Mike and Joanne Stimmler]

Lance,
Check out Steve's Wiki here on his 400 watt bimini

http://www.c34.org/wiki/index.php?title=Solar_Power