Battery Charging Question

[Ward H]

My O'day 25 has one type 24M battery. It is used to start my OB and so far it has been charged only by running my Yamaha T9.9 Outboard.
Simple enough but I only run the outboard for about 30 minutes per day sail and never above 50% throttle.
While sailing the only current draw is the depth sounder and GPS.

The T9.9 specs says it will charge at 6 amps so at 50% throttle I expect it is charging less than 3 amps, probably more like 2 amps.

This does not sound like enough charging to replenish the starting load of two starts per sailing trip.

Do I need some kind of auxiliary charger?

Thanks

 

[seadaddler]

Solar

I have seen many sailors with a small solar panel to top off the battery and could also charge while sailing.
have seen many types of setups from say a 15 to 60 amp solar panels either portable with alligator clips or some times permant setup.
Nick

 

[Maine Sail]

Starting that motor draws very, very little capacity from the battery. However the alt will never really get them full and keep them healthy. Solar or a MARINE batttery charger if you can plug in would be best.

 

[FourPoints]

I added a small solar panel to my boat a couple years ago for exactly the same reason.

http://sailingit.com/blog/boat-projects/solar-panel-mounting-and-installation

Last night was the first time in 2 years I managed to drop the batteries below 12.4v, (I read 12.2v at the panel when I tied up at the dock, or in the ball park of 60% SOC) and that was after having spent Mon and Tues night at the boat with the radio going for 2-3 hours while cleaning, Wed-Thur on the boat with most of the time the auto pilot on while underway, Sat-Sun on the boat, also using the auto pilot for most of the trip, and also spending 6 hours Sat night at the dock with the all the cabin lights and spreader lights and radio going playing cards. Plus the cabin fans were on almost non-stop since Monday through 10pm last night. And for what little draw it adds, one to two cell phones were charged every night from the boat as well.

All that with a 12w solar panel, a 160AH of house bank, and a small 8hp 2 stroke engine for extra charging.

It will take my small panel a full week to fully recharge the bank after the usage I just put it through, but that's fine with me as I don't expect to use the boat this week, not that there isn't any reason I couldn't still go out tonight for a sunset sail one night...


My point behind this whole story is that a well thought out and put together solar setup with an average size house bank will provide you with all the power you will likely need if you are just doing occasional overnights and weekend trips.

 

[Ward H]

Solar sounds good. Jamestown Dist has flex panels on sale. 6 watt or maybe the 12 watt would fit on my forward hatch and they don't require a controller at that low of charging wattage, according to the manual.

Would that be an acceptable way to go?

 

[FourPoints]

the bigger the panel, the faster the (re)charge, and for any panel that is large enough to be of any use, you should always have a controller. Genasun GV-4 is probably the best one you'll find all things considered.

 

[Benny17441]

You are operating your boat like a small powerboat. Running the engine for 30 minutes will likely replace the small use of stored capacity from twice using the starter and running depth sounder and GPS. If you ever desire to overnight in the boat or add other electrical devices it may not be as adequate. I would recommend you carry one of those 12V portable power packs for back up as now you are only depending on that single battery. If you have access to shore power I would add a small 2A maintainer. I'm pricing a group 24 wet cell starting battery at $80 and for that amount I would not go around much trouble or expense to try and extend its life beyond 2-3 years. It is not necessary to kill a gnat with a $5MM tank.

 

[Brian S]

Dang it, my buddy has a 45 watt panel he was going to give to me, but I don't know where I can put it! It would be perfect with that Genasun charge controller. But complete overkill for my U1 320amp tractor battery... I don't have a rear pulpit to hang it over, just my funky O'day 192/222 aft handles. If I tried to put it on the hatch cover, it would have to be removable, otherwise it would get in the way. Actually, for that little battery, a much smaller panel would be more appropriate, I'm sure.

Brian

 

[Ward H]

Brian, any location on my boat will be temporary. The panel will be stored away for sailing.
Think I will get the Geasun controller and 12 watt Ganz flex panel.

 

[FourPoints]

Brian, any location on my boat will be temporary. The panel will be stored away for sailing.
Think I will get the Geasun controller and 12 watt Ganz flex panel.

Ward,

That setup will probably serve you rather well, and should deliver about 1A of charging to your batteries during the day. While 1A isn't a lot, it is enough to keep the batteries nice and topped off for almost any weekend and simple overnight (or 3) use.

I would encourage you to check out the way I mounted my GANZ 12w panel (GANZ even uses, or at least used to use my install in some of the marketing material they display at boat shows). The system was easy to install, and allows the panel to stay unshaded in almost any situation, and takes up very little space. It did add another boat buck or two in cost, but I got the installation the way I wanted so the extra cost was worth it for me. Had I known about marinepartdepot.com at the time it would have been much cheaper than the local and overpriced chandlery where I bought the all of the fittings from.

 

[trainmanjess]

hello all

I purchased 2 - 30 watt solar panels, connectors, and controller from e-bay ... I was very specific on the size of the solar panels... I bought it all for less than $100 on e-bay... I bought 2 panels that would fit side by side on my companionway slider top, and then the cable would go down through it, into the cabin where it would connect into my electrical panel just inside the cabin door way... it works great for me... as I have a toplift on my mast and attached to my boom, I do not have to worry about the boom falling on my solar panels... plus I have used heavy gauge rod to make rounded frame over the panels in 3 places to also protect the solar panels...

next time I am out at the boat, I will take pictures of it..

sincerely
Jess

 

[Benny17441]

Don't waste your money on a 6W solar panel. If you go for a bigger panel make sure you install a controller as you would not want the panel to reverse the process and draw power from the battery at night. I would very much doubt that your outboard alternator is recharging your batteries to the desired 100% as the battery's rate of acceptance drops significantly as it reaches the 90% range. Half an hour will not do what will require 3 or 4 hours. This regiment of undercharge will reflect on the battery's health and longevity over a period of time. What I meant before is that probably you can still get a 2-3 year life span from your battery and that it may not be cost efficient to add a working solar panel installation when a single battery can be inexpensively replaced every couple of years. The addition of shore or solar power may maybe extend the life an additional 2 years. You can do the math. Also a single group 24 battery can be taken home every couple of months and properly recharged and equalized if desired without to much trouble.

 

[Ward H]

Brian,
I like your set up but the Admiral says no to stuff hanging off like that. I think she is saving that starboard stern corner for a BBQ grill.

With you saying i could get possibly 1 amp per day charge, that will probably do the trick for me. I could even use the interior lights once in a while.:dance:
I don't expect to go for the usage you related you get in your set up but I know where to go to for ideas if I decide to go that route.

Benny,
Thanks for the ideas. If I follow what your saying correctly, I am less interested in extending the life of the battery more than a couple of years as I am in ensuring power to start the OB. And this without shore power and on board charger.

 

[Chief RA]

Benny/Ward: If a solar panel is used they usually have a diode wired in to prevent reverse current. Look in the box on the back of panel for a black cylinder hooked inline with your wiring and thats your diode. Sounds like just a 12 watt solar panel will work fine for what you want. Chief

 

[Maine Sail]

Benny/Ward: If a solar panel is used they usually have a diode wired in to prevent reverse current. Look in the box on the back of panel for a black cylinder hooked inline with your wiring and thats your diode. Sounds like just a 12 watt solar panel will work fine for what you want. Chief

Not all panels have a blocking diode in them, especially some of the cheaper eBay etc. ones trying to make good Vmp numbers......

You also don't want to confuse a panels by-pass diodes for blocking diodes. Many panels come with by-pass diodes, for series installations, but these are not the same as a blocking diode and are not wired to act as blocking diodes. Many small panels have neither blocking nor by-pass diodes.

Easiest and safest bet is to just to use a controller, if the panel is actually big enough to actually do anything. If the panel is not big enough to require a controller, then IME it is not worth wasting money on....

 

[Chief RA]

I said "usually" and trying to keep it simple! In this case: controller not really needed!
Chief

 

[cjm1]

You really don't need a controller unless you are in the deep south with a 40 watt panel. I have a 20 watt and a 30 watt panel in parallel to 2 series 31 deep cycle batteries running thru a battery splitter and located in the Great Lakes. I have a controller but never installed it since I never saw a need after I purchased it. I am on a mooring all summer and rarely hook up to dock power. I have used this set up for 30 years and never cooked a bat and usually get 8 years out of a battery. The only mayor power draw other than electronics(minimal) are bilge pump (wood boat) and diesel engine starting. I have always had a charged battery and portable plug in panel should work just fine. The bigger the better.

 

[FourPoints]

I said "usually" and trying to keep it simple! In this case: controller not really needed!
Chief

As mentioned a number of times, if the panel is large enough to actually do anything, a controller is needed, otherwise why bother with having the panel at all?

 

[Maine Sail]

I said "usually" and trying to keep it simple! In this case: controller not really needed!
Chief

I certainly would not want to see a 12W panel direct connected to a single group 24 battery and left unattended for decent periods of time.

I have seen a number of examples of batteries cooked by controller-less panels left unattended.


Do I Need A Solar Controller?

 

[Chief RA]

I am a multi degreed Electronic Engineer (radar,sonar,comm) and that is my interpretation of this issue. I taught electronics (including solar) at Butte college for many years. Chief