AC/Battery relay?

[jyjohnson]

I have a battery/AC question:

When on AC/shore power:
1. I want the 12v panel to be powered by a 12v "wall wart" located inside the boat.
2. I want my battery charger (Noco G750) to be connected to the battery.

When AC power is off:
1. 12v panel to be sourced by the 12v battery.
2. (Charger can remain connected to the battery but is not powered).

This configuration keeps the battery charger from providing power to the 12v appliances when on AC power, which is something the Noco recommends. Note: my boat has just a few 12v components (nav/cabin lights, bilge pump (which normally is dry), radio, etc.).

Any ideas?

 

[Don S/V ILLusion]

Most chargers with which I am familiar are designed and intended to provide DC power to 12v devices. Regardless, appliances cannot differentiate what is powering them.

There is no reason to power your 12v panel with a wall wart. Further, wall warts generate lots of RF, heat and are inefficient. Most people prefer to eliminate them whenever practicable.

 

[kloudie1]

The way to do that is to put in a relay with a 110V coil on a SPDT (single pole, double throw) whose contacts can handle 20 or 30 amperes at 12Volts. https://www.amazon.com/Relay-Power-...8_4?ie=UTF8&psc=1&refRID=HNXARE01NKG7W0CW73ME Assuming your loads from the panel are less than that.. If you are powering a VHF radio, ya going to need at least 6 amperes of clean DC and with a bilge pump, probably 10 or so momentarily.. A wall wart generally will not have enough power out so you'll have to use a 100 watt, 12V power supply that uses 110V input. The relay could be installed behind the DC panel and shore power hooked to the relay coil (through the proper switch etc) The wire feeding the panel from battery would be cut and hooked to the "common" on the relay the wire from the battery would be hooked to the "NC" (normally closed) relay connector. The power supply output would be hooked to the "NO"(normally open) contact. The power supply would be properly connected to the shore power.
When no shore power is applied, the battery would feed the panel through the NC contacts. When shore power is applied, the relay coil would energize, the battery would disconnect at the relay. The power supply would power the panel .. https://www.amazon.com/Henxlco-110V...3543778&sr=8-8&keywords=12v+100w+power+supply
That NOCO 750 is too small for any deep cycle battery.. as a minimum, you'd want the NOCO Gen Mini 1/4 http://www.basspro.com/Noco-Genius-Mini-OnBoard-Marine-Battery-Charger/product/1507241631/ and that is still probably too small.. A marine smart charger with an output of 10 amperes is probably a better choice.. http://www.basspro.com/Marinco-Charge-Pro-Onboard-Battery-Charger/product/2323574/
Not recommending these, just showing a typical..

 

[Benny17441]

That NOCO G750 is described as a trickle charger and maintainer rated at 0.75A. The reason why the manufacturer may recommend there be no 12V items powered is because with such small output it could be easily overwhelmed and not be able to maintain a battery. My idea and my suggestion as well is that you get an inboard smart battery charger of at least 10A and be able to operate 12V fixtures while charging the battery. The NOCO's low output is probably ideally suited to maintain charge to an unloaded battery for a long period of time but normal use of a sailboat requires simultaneous charge/use for convenience. Wall Warts overheat and I do not consider them safe for boat use in prolonged applications. Bite the bullet, see if you can return the NOCO, and get yourself a true charger.

 

[Maine Sail]

I have a battery/AC question:

When on AC/shore power:
1. I want the 12v panel to be powered by a 12v "wall wart" located inside the boat.
2. I want my battery charger (Noco G750) to be connected to the battery.

When AC power is off:
1. 12v panel to be sourced by the 12v battery.
2. (Charger can remain connected to the battery but is not powered).

This configuration keeps the battery charger from providing power to the 12v appliances when on AC power, which is something the Noco recommends. Note: my boat has just a few 12v components (nav/cabin lights, bilge pump (which normally is dry), radio, etc.).

Any ideas?

You need an actual marine battery charger not a maintainer suitable only for a motorcycle sized battery. You are looking at a smart three stage charger upwards of 10A. If buy a 10A charger your dock side loads wind up being 8A then you have 2A left over for charging. Please don't fall prey to non-marine UL battery chargers, they can be dangerous..