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'need a 12 volt educashun...

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millermg
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159 Posts

Initially Posted - 11/11/2006 : 08:46:35

New to 12v power in boats, I'm hoping someone can help me understand on-board battery charging, as it relates to my outboard alternator and solar panel I want to hook up this weekend. My '88 manual states that at that time, only the inboards had charging capabilities, so I'm assuming the charge connector for the outboard was added at some point on my '83. I also read on the post-'88 manual on this site, you should never charge with the batteries in off position, however there's still no reference to the outboard charge wires in the wiring diagram. I've got 2 batteries, and here's my questions:

1) how is the outboard charging wire typically connected to the system, and when and how should I be using it as it relates to the batttery selector switch? If it's on battery 1, does that mean it's charging 1, etc?

2) what is the proper way to hook up the solar panel? Can I simply connect to the outboard charge wire, or do I need to connect to the batteries directly? If the former, do I need to leave the battery switch on when it's trickling?

1983 C25 FK/SR Finistere
Garner
Olympia WA
~/)~
~~~

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 11/11/2006 : 09:47:41

I to am somehat electrically challenged so, in my opinion, there are two electrical areas that are best left to the pros, motor to battery charging system, and shore power hook up.

i as Iunderstand my setup, the charge (alternator) wire and ground on my boat are led to the batt switch, and from there to the batteries. With this setup, the switch controls which battery is charged and which is in use. If "both" is selected a circuit is open to both batts and the least charged will draw power from the most charged batt. A battery combiner is usually added, though not required, to keep this from happening. When the motor is runnning (charging)you cannot switch between 1,2,or both on the switch or the system will short circuit. Without looking at it, I don't know recall how the switch is intergrated into the circuit panel, if it is at all.

My solar panel is a Siemans 10 amp which is connected directly to the house battery. It has it's own charge controller integrated into the wiring by the manufacturer.

I'm sure there will be more advice from the membership as we have some very smart folks who are expert in this rea. Hope I've shed a little light though.

Edited by - on

Dave Bristle
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Djibouti
10005 Posts

Response Posted - 11/11/2006 : 10:04:04

Pick up Don Casey's "12-Volt Bible" at just about any marine store (or Amazon). And remember, 12 volts doesn't sound like much (compared to 110), but there's enough amperage in a 12-volt system to cause a lot of trouble--fires for example. The right wire, the right connections, and the right circuit design are all critical to your safety on the water. The marine environment and the constant motion and vibration of the boat just complicate things further.

Be safe out there...

Edited by - on

Leon Sisson
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1893 Posts

Response Posted - 11/11/2006 : 11:56:26

Garner & Al,

Having wired a few boats, I'd say there's no one single right way to do it. (I've also seen more than one wrong way to do it too!

) A lot depends on how the boat (and hence its electrical system) will be used, what's there to begin with (the older the boat, the less likely it's electrics are to be original, or in good condition), and what you're comfortable doing and spending. As Dave B suggested, a very good place to start is studying a few books on boat electrical systems. For each boat electrical system I designed and installed, I started with a 'blank sheet of paper.' First comes the wish list, then the schematic, then wire size calculations, parts list, planning the physical/mechanical installation, and finally actually building it. Skipping, or not completing, any of these sequential steps is likely to result in more time, work, and money spent on subsequent steps, having to redo something, or a less than optimum final result.

Ok, enough vague pontificating. Here's a link to a rough draft of the [url="http://home.mpinet.net/~sissonl/boating/photos/c25_elec_sch_p2.gif"]charging and high current power distribution[/url] portion of a C-25 electrical system upgrade. Keep in mind what I said about there being more than one way to wire a boat.

-- Leon Sisson

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Champipple
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6855 Posts

Response Posted - 11/11/2006 : 13:41:21

First, the 12 volt bible is written by a guy named brotherton. Case's book is sailboat electrics simplified. You can get both from amazon, please click on the link to amazon on the menu bar and then search for them from there.

Questions 1 - mine is connected as follows. Black wire from the engine runs all the way to the negative terminal on the battery Bank, the red goes back to the 3 way switch. I believe with this setup you are correct, you are only charging what you are connected to via the switch selector position.

I don't know anything about solar panels, so I'll have to pass on that one.

Edited by - Champipple on 11/11/2006 13:42:23

OLarryR
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3467 Posts

Response Posted - 11/12/2006 : 07:06:10

There is of course always the better way to do these hookups and with 2 batteries, that usually means using a battery combiner or isolator or whatever means to ensure that the charging is to each battery separately. Hving said that....I have not invested or changed my hookups to go that route and so far, my outboard and solar panel hvae been charging both batteries fine. It is also possible to charge oe battery by keeping the original selector switch turned to battery one and then the next week or so turn it to battery 2. But this becomes a boat management issue which you may not want to bother with.

In hooking up my solar panel (see website) there are some basic things that I picked up thru reading matl: Do not hook up the solar panel in series with the outboard motor. Also, if you use more than a 5 watt solar panel per battery, then you need a solar controller or you will cook off excess water from the batteries.

I have a 2006 Honda 9.9HP with a 12 watt alternator. The positive lead is hooked up thru the battery selector. I have a Kyocera 20 watt solar panel hooked up to a Morningstar Pro 15M controller. I originally hooked up the leads coming from the controller to a 12 volt adapter plug and plugged that into my 12 volt accessory adapeter. That is by far the easiest method of connection. The 12 volt plug has a fuse in it, so the solar leads/controller,etc are protected and the acessory plug is wired into the accessory switch on the switch panel...so if the battery is on "both" and the selector switch is "on", then the batteries are being charged by the solar panel if the sun is out and....if the motor is on...well then the outboard motor is charging and the solar controller protects/isolates any effects from the outboard ...basically the two charging units are in parallel, not series.

But after 3/4 of a year using the 12 volt accessory lug, I became tired of having the wires hanging partially over one of the seat cushions, so I recently hardwired the solar controller leads...which is really just as easy as using the 12 volt accessory plug. With 2 battery banks here is an easy way to do it: The negative wire is a "no brainer", you hook that to one of the wing nuts on the battery common negative connecting the two batteries. The positive lead can be connected to the positive wire terminals that go the original Catalina Switch Panel Circuit Breaker. ON my boat, that connection is at the top of the panel and so the terminals off that breaker are easy to get to. I connected to the terminal that provides circuit breaker protection - that is the side that has the bare wire ruinning down to all the switches versus the other terminal that leads to the battery switch. Once hooked up, solar controller is basically wired same as it was thru the 12 volt accessory plug but now the wires are sll hidden. (I still have to update my website with the hardwiring upgrade.)

Right now...I have not gone the battery combiner, etc means of isolating the two batteries when charging. I pretty much leave the battery switch in the "both" position all the time and take my chances on the degradation effects of one battery effecting the other. One day, I may change my thinking/arrangement. Constantly switching to one battery when running the outboard or every other week or so for the solar controller would be one manual way to isolate the effects of one battery effecting the other without any addl electronic smarts or dough. But that to me is too much trouble to be thinking about all the time...so my thinking is to treat them as one battery or go the battery combiner route. Each one has to decide what is best for them...and there is always room for future improvements.

Edited by - on

Dave Bristle
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Djibouti
10005 Posts

Response Posted - 11/12/2006 : 10:03:39

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Duane Wolff
 First, the 12 volt bible is written by a guy named brotherton. Case's book is sailboat electrics simplified.<hr height="1" noshade id="quote"></blockquote id="quote">
Duane's right, of course...

Both are good books, and it doesn't hurt to have more than one--to compare approaches... or pick up tidbits another book omits.

On Leon's subject of more than one way... I was impressed by a writeup about a dual-battery system in the West Marine catalog--using a couple of new components including an alternative to the standard 1-2-Both switch with or without an isolator. It made a lot of sense to me, and I'm probably having it built into my new boat--I'm discussing it with the builder and he seems to agree--I still want to discuss it with a friend/expert who is presently halfway down the ICW on his sailboat. I won't try to describe it here for fear of getting it wrong--you can read about it in the catalog.

Edited by - on

mashedcat
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Response Posted - 11/12/2006 : 22:24:11

I read the same article Dave did about foolproof 12 volt wiring. I felt about it the same way he did. Im moving my panel to stbd this winter and adding a 2nd battery. When I do that, I'm going to incorporate the WM ideas into my system. You can find their article in the electrical section of their catalog. I too am a large fan of Don Casey's 'Sailboat Electrics Simplified'. Very understandable. It also applies well to our boats because we dont have really complicated wiring.

Edited by - on

Bubba
Admiral

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USA
542 Posts

Response Posted - 11/13/2006 : 18:46:38

FYI: West Marine also has those articles online at [url="http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorListView?storeId=10001&langId=-1&catalogId=10001"]West Advisor[/url].

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dblitz
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240 Posts

Response Posted - 11/13/2006 : 19:36:11

How about this question? Over the summer, I bought a solar panel at boater's world, that I never had a chance to use. I'm thinking of leaving the batteries on the boat over the winter with the battery switch set to both and the solar panel plugged into the 12 volt female plug. Is this a bad idea?

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mashedcat
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194 Posts

Response Posted - 11/14/2006 : 00:28:41

to Dave: thanks for the tip.

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OLarryR
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3467 Posts

Response Posted - 11/14/2006 : 05:51:59

Daniel,

I provided a response that covers exactly the hookup you are talking about...without a battery combiner, etc. It's okay to do it that way but if one of the batteries is weaker or has a defect, then the good battery does not get full benefit from the solar panel with the switch in the "both" position. The weaker battery kind of saps the strength from the good battery unless diodes are installed so there is no crosstalk. A battery combiner or a battery isolator is the best way to go but for now, i have not gone that route. I am been using the setup as you described with no issues so far...that's about one year and counting.

The only thing that one really needs to attend to is if the solar panel is more than 5 watts per battery, then a solar controller is needed or there is risk of cooking off the water in the battery. 5 watts on each battery is okay because that is about .3 amps/hr and typically a 5 watt panel (or 10 watts for two batteries) will not charge constantly at it's max rating. It will probably be closer to about 50% to 70& of the rating due to the angle of the sun. then there are the rain and overcast days when it does no charging at all. The story is that the battery loses it's charge just sitting around at about .5 to .9 amps a day depending on whether it is hot or cold outside (winter versus summer). So...if you get say on the average out of a 5 watt panel, .15 amps for 5 hrs a day then you are charging at approx .75 amps/day which will be about what the battery loses each day. So..then no controller is needed. Just check the battery water occasionally which should be done anyway.

I have a 20 watt panel which can put out 1.2 amps if conditions outside are perfect and I have a perfect tilt to the panel (and I do leave it on a tilt during the winter months). But even so, the angle is never perfect and I generally get about .5 to .8 amps/hr versus 1.2 amps/hr max. I have solar controller that prevents overcharging my two batteries. I still check the water from time to time but it only loses what is normal requiring perhaps adding water once or twice a year. (See website for more details on my solar panel setup including the brackets I made that allow for tilting the panel and removal of the outboard without adjusting or removing the panel.)

Edited by - on

millermg
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159 Posts

Response Posted - 11/14/2006 : 14:00:32

Similar question as Daniel's- with a twist:
What about leaving the solar panel plugged into the outboard alternator charge plug (rather than keeping it plugged into the outboard) over the winter? The location there is so dang convenient w/ mounting a panel on the stern rail.

Thanks

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