Solar Panel Battery Tender

[SteveM]

Does anyone have experience with installing or using a Solar Panel Battery Tender?

My dock in the Bahamas does not have power in order to plug in and charge the batteries. Very far and expensive to run all that copper, I've gotten estimates in the $6 grand plus range for install of power.
For the brief amount of time it sits at the dock (1 or 2 months) I'm having a tough time justifying the hard wired install.

If I could get a solar or wind powered battery tender that might be all I need.

Would love to hear from someone who has already made the mistakes, or bought a good product, or bad product, etc.

Or even if you think this is a bad idea. Thank you.

[Yannis]

What is a battery tender?

[Tommy]

Solar powered charging

[Yannis]

do you want to install a solar panel that will be charging your batteries when you're not there?

[mike ohlstein]

I have three of them and use them to trickle charge my batteries over the winter. They work fine for me, as long as they're not covered in snow. In retrospect, a wind powered deal would have been a better idea. All of the sailboat guys have them....... so I figured that they were stupid.

Apparently, those guys have a good idea once in a while.

http://www.batterytender.com/Solar/15-W ... oller.html

[SteveM]

Yes. The intent is to charge the batteries in order to simply keep the bilge pumps running when needed. And of course start the boat.

[Navatech]

Personally, I don't like the noise wind generators create... I'd go for solar power, especially in the Bahamas, before I'd go for wind power...

Installing a solar unit is also simpler then installing a wind unit...

[Navatech]

What is a battery tender?

Sometimes they're called "trickle chargers"... Basically it's a small charger intended to compensate for the fact that batteries loose their charge over time...

[Charlie J]

what about a portable generator with a battery charger
every now and then fire it up

[Navatech]

what about a portable generator with a battery charger
every now and then fire it up

That WOULD work BUT it wouldn't be "automatic"... IOW, you'd have to remember to go down to the boat, start up the generator, hook up the charger and then hang around for an hour or so till the battery was fully charged... With a solar (or wind) setup you wouldn't have to do anything... And your battery would be fully charged all the time...

[Yannis]

Nav, thanks.

Mike, the sailboat guys use wind chargers because, one, it is very difficult to place a solar panel on a sailboat deck as it will always be in the way and, two, the mast and all other cables and lines will shade it so it will barely be working. They sometimes use flexible panels that you can step on, but they're twice the cost and half the output for a given size, plus, they still suffer from the said shades. They sometimes hang them on the rails or they create an arc aft of the cockpit and place the panels up there. In the bahamas the sun is abundant so solar is preferable.

Steve, i started with one panel of 130 watts and last year i added a second identical one from victron. Coupled to a control panel (that you can turn them on/off from, plus check if the batteries are charging or are full) and i have full batteries 365/365, run a fridge and freezer, all lights and all pumps. I no longer carry any cables for shore power at all !!

[DanielM]

I have an off the grid fishing cabin. The car battery we use to start the generator was always down when we went out there. On the way out one night I went to the local sporting goods store and just bought the mid-range solar trickle charger. Maybe $40 bucks. Can't remember the brand. I was in a hurry as we were leaving to go to the camp in the morning, so I got something cheap with the intent to do more research later and get a better unit....That was about a year and a half ago and it's still keeping the battery up.

You probably would want something a little more sophisticated for the boat, but sometimes a simple solution is all you need. Those solar trickle chargers are pretty well known technology . Definitely a good idea.

[SteveM]

Thanks for all the positive replies and good information. If no one at our shared dock would bitch at me, I think I might mount the solar panel on the dock on an elevated pole. I bet I could even run dock lights and security with Solar as well.

My resolution for filling the water tank was also creative. We do not have running water down at the neighborhood dock. So I purchased a 42 gallon tank on wheels that I can trailer with the golf cart (which has a trailer ball) to the dock. I'll fill this up at our house with fresh water. I was able to find a cap by the same with the garden hose fitting. So instead of the 3" drain tube, I have a cap with a hose fitting. I can drain the tank to the boat with gravity and then run my fresh water wash down. I only carry about 19 gallons with the stock water tank and I can cut through that quickly.



The water tank and the solar battery charger allow me to use my own dock instead of going to the marina nearby which was costing me about $1,500/month.

[Bruce]

Any type of solar charge will keep the batteries up, but say a hose leaks and the pumps start cranking it won't come close to keeping up with the current draw if that enters your mind.

[Dug]

I've thought about that solution. I have shore power but its not formal at all. I plug an extension cord into the house where the dock is and occasionally it gets knocked loose and I have dead batteries when I arrive. I also like to keep the refrigerator running to keep the contents cool. Friday night beverages at the dock to relax has been pleasant...

But would solar keep the fridge up too? I am wondering the size of the panel I would have to install.

I would not put it on the boat but would do the pole on the piling as well, as long as the owner of the dock would let me. In CT we do get rainy days and that might mean no juice or definitely not enough. And the boat is in a place where wind is not present regularly so the windmill would not work well.

Any thoughts on the size of the necessary panel given my scenario? If it were just batteries I'd love the idea! Of course I could shut off the fridge and it would not be an issue... but whats the fun in that!?

[mike ohlstein]

Any thoughts on the size of the necessary panel given my scenario?

Think football field.....

[Dug]

Yep, as I suspected. Side benefit Mike, it would keep rain from falling on the boat! LOL!

[Navatech]

Think football field.....

I think this rather depends on the size of the fridge... Yannis has (IIRC) 2 solar panels on his 28'... And, according to him, these are enough to charge his batteries and keep the fridge going... In addition to lights and (presumably) intermittent bilge pumping...

[STraenkle]

Nav, not to offend, but I think Mike might have been using just a tad of Sarcasm. Simple math of the energy usage of a fridge, size of panel, latitude..... not beyond his gray matter by any stretch of the imagination. Not everything needs to be analyzed, that's all.

[Yannis]

Here's my 1st panel before installation. I think 80 x 120 cm or close. Important: 36 cell panel. Here you can also see the width of the fridge and freezer insulation. I think 10cm in the fridge and 15 in the freezer.



This is the control panel. I never touched it since its installation. It's always ON, with the fridge always on too.





This is when I had one panel only. The reason I put a second one was that in the bay of Syros island where I spend quite some time in late August/early September there is a hill that blocks the sun after 4pm. With the second panel I have 14 volts 24/24 no matter how much I consume. I make ice daily in the -18 C freezer non stop, BUT the fridge/freezer combo has to open from the top and be well insulated all around and below.


With 2 panels last summer. No need to carry any cables at all anymore.

[Tony Meola]

Dug

I am not up on this stuff but from what I have seen, and others can chime in, would this work?

If you just set up the solar to charge a good size house battery and then hooked that up to an inverter. Given the potential draw, I would think it would take about two days of the Fridge running to pull down the battery. Then figure that at least one panel dedicated to that battery is charging it, you might get 7 days out of it. So enough for you to recharge by running the engines when you visit the boat. A second panel would be dedicated to keeping he bilge batteries up to snuff.

[mike ohlstein]

Nav, not to offend, but I think Mike might have been using just a tad of Sarcasm. Simple math of the energy usage of a fridge, size of panel, latitude..... not beyond his gray matter by any stretch of the imagination. Not everything needs to be analyzed, that's all.

Pie R Round, Cake R Square.

[Stephan]

Gents-
I agree with what's stated above but also want to add that the solar chargers can be a very good fit with AGM batteries. I am told that when recharging AGMs they have a very high initial acceptance rate but that tails off as full charge is approached. The relatively small charge of the solar panels does a good job of topping the AGM batteries up that last few percentages which is good for their overall life and performance.
Regards,
Stephan

[Capt Rex]

Research it a couple months ago and came up with these two I believe top of the line semi flexible systems, best power for there size, lend themselves to tack right onto a bimini both with built in regulators:

OceanPlanet Energy
72 Front Street Bath, ME 04530 207-370-9112
SP 72 All1
33.7”/855mm
21.5”/546mm
72W
6AMP
18-22Ahs/day
$749

Hamilton and Ferris solar panel 100w 5.5amp, 41.7" x 21.3" 10 yr Warrantee 508 743-9901 ; http://www.cartserver.com/sc/cart.cgi $1,099

When I can take off enough time, I'm hankering to head your way!

[Yannis]

Capt Rex,

I think what you're proposing is WAY too expensive.
Mine are 130w and didnt cost more than 200-230 euros each. Plus 40 or so for the regulator.

[Tony Meola]

Capt Rex,

I think what you're proposing is WAY too expensive.
Mine are 130w and didnt cost more than 200-230 euros each. Plus 40 or so for the regulator.

Yannis

Who makes the ones you have?

[Yannis]

Victron energy.
Google it, they're one of the leading companies worldwide.

[Tony Meola]

Thank you

Actually very helpful

[fonsim]

Victron energy.
Google it, they're one of the leading companies worldwide.

Yannis:

Did you have a bank of batteries for that or just a battery for accessories? In my boat I have 3 batteries, one for each motor and one for accessories. I don't know if everybody have the same configuration.

[Yannis]

Fonsim,

I have 4 x 100 amp batteries, two on the outside of each motor.
One, is dedicated to one motor; the other three are house and other motor.
The solar system charges the three batteries when the battery switch is on position "one".
However if i choose "both", then the solar panels charge all 4 batteries ( the 3 batts give power to the 4th), but i usually don't mix that single battery with the others, as it is not used in any other function but to start the port engine. It charges by the engine when it runs, and that's plenty.
If this battery, for some reason becomes low, then i switch to both and start the port engine with the other batteries.
If all are dead (....never, but assuming they all die on me) i wait till tomorrow. At 10 am im back at 14 volts again. No cables no genny, just the sun and a couple of bacardis...
My electrical skills are like my cat's knowledge about space rockets...

[Yannis]

Hey, Fonsim, I looked at my wheels, there doesn't seem to be any inscription on them whatsoever; strange, next time ill look more thoroughly.

[fonsim]

Hey, Fonsim, I looked at my wheels, there doesn't seem to be any inscription on them whatsoever; strange, next time ill look more thoroughly.

????

[Yannis]

In the thread "generator in a B28", JH asked me what wheels I'm running. I thought it had been you, sorry. I should have posted it there...