Automatic 12vdc with shore power

[Hardcrab]

Does anybody think this would be a good setup?
When 115vac shore power is applied, the boats standard 12 vdc system is switched automatically from battery power
to a 115vac transformer/ rectifier /filtered 12 vdc power supply.
I'm thinking 10 amps would be enough for most usages expected.
This is independent of any battery and battery charger system normal operation.
Use 12vdc items without a care in the world about battery drainage, while plugged in at the dock (cabin lights,vhf radio, fm radio, etc.)
The instant shore power is disconnected, everything returns to normal battery power.

Any thoughts on this idea?

[Hamin' X]

Sounds like a typical RV setup. They can get quite expensive. Some have battery chargers and inverters built-in. When on DC the inverter supplies the AC outlets and when on AC it goes direct. Same for the DC systems. When on AC the DC lights and stuff work from the power supply and when on DC they run direct from the batteries. I'm sure that some outfit makes a "marine" quality device like this.

~Rich

[Nautek]

Seems very complicated when all you need is a good battery charger.
You still run off the batteries but the charger keeps them topped up.
The less complex a system the less problems you have with it.

Allan

[Hardcrab]

I'm about to build one. Cost will be less than $50 using Harbor Freight, Radio Shack, and my scrounge box.
Very simple actually. A standard "dumb" 12v battery charger, DPDT 12v relay, a better diode bridge, add some caps as filters and I'll have a stand alone, rock solid, 10 amps good to go at the dock.
All of the necessary added parts will fit in the charger box, to be mounted/used under the galley area, close to the batteries.



Nautek,
I first thought about using my battery charger in this mode, but decided against it. My onboard charger is a newer "smart" charger and the added loads for the house load might confuse the charging rates. I didn't want to take a chance on hurting the batteries/charger, and I don't care to research the circuitry to find out.
Besides, it would not have the nifty fully automatic feature I'll incorporate.
It's not complex at all.

[delevi]

All you need is a shore power cable and a standard outlet on the other end. Then plug in a power strip on that end for any 110v accessories you want to run. I also have a dual 12 amp charger (6x6) hard wired to the batteries. When I plug in the shore power, the charger plugs into the power strip. It is a smart charger which will trickle mode when batteries are charged. When in the slip, my boat is plugged in all the time. I also have a 350 watt inverter, hard wired to run the laptop, etc, when shore power is not available. Whole setup is under $200. Just one way to do it.

Leon

[HERNDON]

Leon:

I assume there is no problem closing and locking the hatch with the
cable running in?

Rob

[delevi]

No problem Rob. The gaps on the sides of the lip of the hatch are plenty big for a power cable.

Leon

[Graham Carr]

I have an on board 12 amp smart -charger which is hard wired to the batteries. For power I installed a “MARINCO” Battery Charger Inlet - 15A. I mounted the inlet at the stern (engine well) on the starboard side. This allows for quick extension cord connection without opening covers or hatches. I mounted the charger next to the batteries. To complete the circuit from the inlet to the charger, I hard wired an extension chord to the inlet. The female end on the extension cord plugs into the charger. The extension chord is a contractor grade 12/3. These yellow cords are designed for outdoor use at construction sites. They have a rugged insulation which is resistant to abrasion, ozone, oil, grease and chemicals and they stay flexible down to -67°. The outer jacket is flame retardant and water resistant and is sealed to both female/male ends. The installation is very simple. Decide were you would like the inlet plug to be mounted. Using a hole-saw cut your mounting hole. Attach the female end next to the chargers so the connection will stay out of the bilge. Next cut the cable to length. Mine is routed aft in the bilge area and has 2 extra feet which allows for movement. Next cut the cable, strip and connect to the screw terminals. Secure the inlet plug and you’re done.
For convenience I mounted a GFIC outlet in a weather proof exterior outlet box with a clear weatherproof cover on a post in my boats parking space. Please note a regular weather proof box is only rated for dry conditions, no cords plug in while raining. So you mount the weatherproof clear cove onto the weatherproof box. Now the cord can remain plugged in during rain and snow. The post was placed so when I back the boat in, it is located next to the inlet plug. I then took the other end of the cut off extension chord (female end) and mount a new watertight plug on it. So the female end attaches to the inlet plug on the boat end the new plug on the spare cord is plugged into the post. When I take the boat out, I leave the cord coiled up on the post. I have another uncut cord for the marina slips.

Graham

Inlet Plug

Hole saw

Extension cord

Watertight plug

Weatherproof elec box

[Highlander]

Here's what I'm in the process of doing, in this pic you can see the extra heavier wire I added for the 12volt system
http://i235.photobucket.com/albums/ee20 ... 010072.jpg
in this pic is my 110ac main panel rear view

http://i235.photobucket.com/albums/ee20 ... 010073.jpg

front view
http://i235.photobucket.com/albums/ee20 ... 010077.jpg
http://i235.photobucket.com/albums/ee20 ... 010078.jpg

110ac/12volt d/c Elect, panels below the sliding galley & front seat of the dinnete table

http://i235.photobucket.com/albums/ee20 ... 010080.jpg
http://i235.photobucket.com/albums/ee20 ... 010083.jpg

my dual auto matic 6x6 battery charger same as Leon's I beleive
http://i235.photobucket.com/albums/ee20 ... 010088.jpg

battery switch
http://i235.photobucket.com/albums/ee20 ... 010091.jpg
My hydro inlet is installed at the same location as this mac26m aft port under the helmans seat
http://i235.photobucket.com/albums/ee20 ... 010044.jpg
Yet to be installed 12volt acc panel
http://i235.photobucket.com/albums/ee20 ... 010097.jpg
http://i235.photobucket.com/albums/ee20 ... 010099.jpg

All bought at my local marine flea market for $15. to $25. a peice including all the 110v a/c marine wiring harnesses My Scottish heritage coming out on me
with this set up when plugged in at the dock you can use all your 12v d/c access as the battery charger will keep the batts charged all within reason of course !

J