Automatic inverter switch over

stuhaynes

stuhaynes

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I've just bought a soft start 1500w inverter plus new deep cycle batteries and am looking for a bit of advice. My current setup for mains is shore power only. Our marina is a bit prone to power cuts particularly at weekends and holidays. I would like to continue on shore power, while ever it's there, but wire in the inverter so that it kicks in when the power fails and kicks out when mains power is reinstated, without causing damage.

Does anyone have a wiring diagram? I'm sure I'm going to need a relay of some description but I could do with advice about this too.

Any help would be much appreciated. Thanks in advance.
 
nimbusgb said:
What are you running off the inverter that needs to be on when you are away from the boat?

Can you stand a short delay in the changeover function or do you want a true 'UPS' uninterrupted supply?
Click to expand...

Mostly the freezer, but it would be nice if the TV didn't go off up to a dozen times on a Friday / Satureday. UPS would be good if it were economically viable but a short delay wouldn't be the end of the world either. We spend most of the year aboard

Stu
 
The simplest way would be to run the TV and the freezer circuit from the inverter all the time. Run a fat battery charger from the mains. Hopefully your TV and Freezer are only a couple of hundred watts each, even so you will need a good sized charger to keep up with the inverter.

Make sure the inverter has a low voltage cut out otherwise you will kill the batteries.

Another alternative, don't worry about the fridge since it isn't instantly going to heat up if the power goes off even for an hour or two, just run the TV off the inverter, job done. At say 200w for the TV you will be using about 20 amps from the batteries so a minimum 30 or 40 amp charger should make sure that you are not actually draining the batteries until the mains power fails.
 
Last edited:
Get yourself a 3 pole changeover relay/contactor with a mains operation coil.

Connect the inverter (line and neutral to 2 of the normally closed contacts. connect the mains shore power to the same 2 of the the normally open contacts. Connect the common to the boat distribution panel.

The on/off of the inverter or the 12VDC supply be connected the 3rd normally open contact and common.

The incoming shore mains be connected across the coil.

When shore mains on relay energized and shore mains connected to distribution panel.

When shore mains is off relay d energized and inverter connected to distribution panel and 12VDC supply connected to input of inverter.

If you do not understand the above do not attempt this and get an electrical engineer to do it for you.
 
stuhaynes said:
I've just bought a soft start 1500w inverter plus new deep cycle batteries and am looking for a bit of advice. My current setup for mains is shore power only. Our marina is a bit prone to power cuts particularly at weekends and holidays. I would like to continue on shore power, while ever it's there, but wire in the inverter so that it kicks in when the power fails and kicks out when mains power is reinstated, without causing damage.

Does anyone have a wiring diagram? I'm sure I'm going to need a relay of some description but I could do with advice about this too.

Any help would be much appreciated. Thanks in advance.
Click to expand...

You could do the same as the set-up on our boat, and run the fridge and TV from the inverter at all times, and supply the battery from a Stirling battery charger. This will "float" the battery when no load and raise its charge current when a load comes on the battery from the inverter.

We have never had a problem with this set-up, and know that the battery is always fully charged when in a marina.

When we are not in a marina, we still run the fridge and TV from the inverter to give a stable voltage to the TV rather than run the TV from 12V when the battery may be partially discharged.

The Stirling charger runs all 12v services/inverter when on shore power.

The only thing we run directly from 240v when on shore power is the kettle, and sometimes a fan heater.
 
stuhaynes said:
I've just bought a soft start 1500w inverter plus new deep cycle batteries and am looking for a bit of advice. My current setup for mains is shore power only. Our marina is a bit prone to power cuts particularly at weekends and holidays. I would like to continue on shore power, while ever it's there, but wire in the inverter so that it kicks in when the power fails and kicks out when mains power is reinstated, without causing damage.

Does anyone have a wiring diagram? I'm sure I'm going to need a relay of some description but I could do with advice about this too.

Any help would be much appreciated. Thanks in advance.
Click to expand...

There are combined Inverter/Chargers available (Sterling for one but I am sure there are other makes)
I would sell the inverter you have just bought and buy the proper tool for the job.
 
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