Battery charger - solar vs. standard install

JoeStang

1 year old 276 cuddy with dual batteries & switch. I didnt elect shore power, so its only charging the batteries with alternator.

I havent had any issues even after the boat sitting for a couple weeks, but it'd be nice to know the batteries are topped off when I set off, and I assume it'd extend battery life.

I thought about installing a dual bank charger, but would a decent solar charger get them topped up over 3-5 days? Just weighing my options.

Black_Diamond

Do you keep it in the water? If so the Mercathode will drain your batteries. Solar chargers can do a good job if you get a good array and charger. Tons of info on sailboat forums for this.

JoeStang

Yes, it is in a slip all summer.

Is the mercathode on even with the battery switch off? (I always turn the switch off when leaving).

212rowboat

It and the bilge should be a direct wire to battery... Radio too.

Black_Diamond

Yes, Mercathode is always on and you want it that way to protect your outdrive.

Michael T

That mercathode system is good anytime your boat is in the water but, in my opinion it is essential if you leave your boat in the weater for extended periods of time. If there ia any chance that there are stray electrical currents at your boat slip/marina (I'd say that was about 99% likely) you sure want that mercathode on. MT

Capt Ron

I would stay with the battery charger... solar panels are more of an add on to top up batteries since they are yet to be that efficient to replace a battery charger. Until they come up with a panel that gives you 30 -40 amps, the battery charger is the way to go. I just find the panels cost so much and the power they generate still very low.

Black_Diamond

Even without stray currents, the Bravo III with its aluminum housing and the dual large SS props create their own current, without the Mercathode and the 'zincs' your outdrive would be destroyed.

 

If running other drives, then yes the stray currents at a marina can be just as bad (and deadly too).

Capt Ron

Just having a boat next to you with a lousy ground will eat up your anodes. It happened to me, an old Searay was parked in the slip next to me and my anodes disappeared in one season, roughly 4 months. When the Searay was moved, I could last at least two seasons on one set of anodes and I'm in fresh water.

Michael T

I used magnesium (ONLY meant for resh water) anodes instead of zinc anodes for the first time this year. The anodes showed quite a bit more deterioration that the zinc anodes did in years past BUT the B3 drives were absolutely pristine. Anodes and the proper ones for your boating area are definately a critical preventative measure. P.S. I did a lot of reading a while back on solar panels and battery charging. I think Arizona Light and Power had a great website. One of the things I remember reading was the need to have a high quality charge regulator to prevent the batteries from being damaged. There are several decent  brands and charging capacity sytems available and two distinct models flexible and fixed, available. The systems keep getting better. The Australians, many of whom, live off the grid have some neat compact solar charging solutions as well. MT 

TikiHut2

As an old sailor who kept our boat at a dock without electric, I always had a solar panel on to charge batteries when we didn't have the engine running. It was cumbersome and a complicated system to make sure it wouldn't overcharge but if you don't have power then it's a necessary evil.

I can't speak for the current that a Mercathode system uses or the addl amperage(minimal) needed to keep the batteries topped off but as was said there are numerous discussions on sailing forums along with excel spread sheets to calculate the right sized panels and regulators that you'd need. A med sized fixed panel with an integrated regulator/controller mounted at the ideal angle on the dock would solve storage and mounting issues but it won't be real inexpensive. As an additional side note ANY sized shadow across the panel has a dramatic effect on efficiency.

Here's a link to start with (LINK)

And an OCD sailor engineer who has a great page of virtually every marine idea/fix known. (LINK)

Good luck, Mike

JoeStang

Great info guys, thanks.

Sounds like I should stick with a standard charger, as I have dockside power. I didnt have to charge the batteries at all this whole season, so I wonder if its REALLY necessary. Even after running the radio/lights for a half day the house battery still had plenty of juice. I never use the "combined" mode, so the starting battery is always just for starting.

JoeStang

What about people that rack store? I'd guess they almost never charge the batteries between trips out, and I dont seem to hear stories about early battery failure or dead batteries on the water.....

Black_Diamond

The Mercathode only will draw power if you are in the water.  We have a rack storage at my port..every weekend dead batteries either at the start or being towed in...(besides breakdowns and running out of gas lol)  I bet they do not get the life out of the batteries unless they use the boat a lot and disconnect in the winter.  I still do mine every 3 years (flooded type).

212rowboat

It's drive season for me, and I've been away..

The Taliban (neighbors kids) watch the house and feed the critters whilst I'm out.. there was heavy rain.. the boat is covered in the side yard.. the young terrorist reported to me via text "drew, your boat is peeing from a hole on the port side near the stern, should we do anything about that?"..

I got back yesterday and around to it today.. seems there was some leaves from a live oak (i hate those trees) that had infiltrated the engine compartment and drifted to the drain, effectively (but partially) obstructing it..

They said it 'tinkled' most the day Thursday after Christmas..

The solar panel on it has kept the batteries topped.. I tested both static and under load, and they are good to go.. the solar panel is about the size of a sheet of paper, and generates 30w @ 22 nominal vdc, and the controller sizes it down to a clean 12vdc and kills the reverse when it isn't charging.. I'm happy with it.. I've one on the top of my camper top, too, charging a tool box mounted battery, which operates a transfer pump and/or compressor when I need them...

$30 each they cost, from amazon.. I'll be getting more of them for various things I want to do... One of which is a battery which takes momentary duties between shore power and generated power on an automatic transfer switch, and another is for a universal power supply, in which I'll use a bank of them, seriesed to produce 300w @ 12vdc..

Long story to say: you will be fine with a good solar tender, methinks.

JoeStang

Got a link on Amazon Drew?

I havent bought anything yet, but would like to get it before spring in case I need to do any wiring/install for either system.

If I was to go with the standard setup I'd get something like this: http://www.overtons.com/modperl/product/details.cgi?pdesc=ProMariner-ProSport-8-Onboard-Battery-Charger&i=87113&r=view&from=grid