installing 12v to 120v inverter

[jecooper]

Hi, all, i installed a 2000w 12v to 120v inverter on my 1996 Sea Ray 25ft sun dancer, there was plenty of room in the engine compartment and a 120v receptacle near by, I thought i could install the inverter and back feed the 120v receptacle to power the rest of the boat with 120v power. Seems i'm wrong, when i turn on the power the receptacle that i backfed, has power to that socket, but no A/C power to the rest of the boat, am i missing something?

 

[airshot]

I am no electrician in any way, but I have used the small inverters on many ocassions. I have found they only work well powering one device at a time, not sure why..

 

[tpenfield]

I have an inverter on my boat. The way they work is nothing short of magic (IMO ) . So, to properly install an inverter I assume you have to be a magician.

Not sure what you mean by backfeed, but with shore power connected, the inverter should be passing the 120v through rather than making the AC current from the battery bank. Got any more info on how you wired the inverter to shore power and any AC outlets/appliances?

BTW - when you added the inverter, how many batteries did you add?

 

[Scott Danforth]

Hi, all, i installed a 2000w 12v to 120v inverter on my 1996 Sea Ray 25ft sun dancer, there was plenty of room in the engine compartment and a 120v receptacle near by, I thought i could install the inverter and back feed the 120v receptacle to power the rest of the boat with 120v power. Seems i'm wrong, when i turn on the power the receptacle that i backfed, has power to that socket, but no A/C power to the rest of the boat, am i missing something?

Explain what you mean by "backfeeding"?

you mean putting AC in the outlet and then hoping to get lots of 12 volt juice out the other end?

They do not work that way.

Inverters only work one way. you put DC in on one end and you get AC out the other. As Ted mentioned, when you add an inverter to get 120 volts AC to feed something like a fridge or microwave, you need to have a lot of batteries to supply the input side. For example, Ted's boat has 7 batteries.

 

[dingbat]

At full load a 2000W convertor draws roughly 166 amps of 12VDC per hour to “make” 15 amps of 120VAC

If you using a 200 amp battery you have less than a 1/2 hour before the battery hits 50% DOD

Are you running a Sine wave, modified Sine or a square wave rectifier?

Makes a huge difference in performance and consumption of the device being powered.

The electric coming out of your home socket is sine. Running a motor on modified sine requires roughly 20% more current. A square wave units is pretty useless unless running a light bulb

 

[jecooper]

I have an inverter on my boat. The way they work is nothing short of magic (IMO ) . So, to properly install an inverter I assume you have to be a magician.

Not sure what you mean by backfeed, but with shore power connected, the inverter should be passing the 120v through rather than making the AC current from the battery bank. Got any more info on how you wired the inverter to shore power and any AC outlets/appliances?

BTW - when you added the inverter, how many batteries did you add?

thanks for your reply, by backfeed i mean that i connected the out put of the inverter to the nearest 120v plug, thinking it would energize all the a/c circuit. I have two marine batteries, the inverter would only be use on short time frames, like running a small appliance for a short period of time

 

[jecooper]

At full load a 2000W convertor draws roughly 166 amps of 12VDC per hour to “make” 15 amps of 120VAC

If you using a 200 amp battery you have less than a 1/2 hour before the battery hits 50% DOD

Are you running a Sine wave, modified Sine or a square wave rectifier?

Makes a huge difference in performance and consumption of the device being powered.

The electric coming out of your home socket is sine. Running a motor on modified sine requires roughly 20% more current. A square wave units is pretty useless unless running a light bulb

the inverter will be used for short periods, while i'm at sea, just to run a small appliance for a short period

 

[jecooper]

Explain what you mean by "backfeeding"?

you mean putting AC in the outlet and then hoping to get lots of 12 volt juice out the other end?

They do not work that way.

Inverters only work one way. you put DC in on one end and you get AC out the other. As Ted mentioned, when you add an inverter to get 120 volts AC to feed something like a fridge or microwave, you need to have a lot of batteries to supply the input side. For example, Ted's boat has 7 batteries.

the inverter will only be used for sort periods of time when i'm at sea. it will be used to run a small appliance like a blender, to mix bait.

 

[tpenfield]

As far as the other AC outlets ( I suppose there are a few). If they were daisy-chained, then you should see power on all outlets. If they were not daisy-chained then each (or some of them) would go back to the AC power panel, which is probably in the cabin.

Also, it is a bad (bad) practice to connect the inverter output directly to an outlet. Generally, the inverter feed should go to the electrical panel as a main source of 120VAC. You will also want to study up on the operation of the inverter (which brand/model do you have) to understand if it should pass AC power through when connected to shore power, charge the battery bank as needed, etc.

 

[jecooper]

Hi, all, i installed a 2000w 12v to 120v inverter on my 1996 Sea Ray 25ft sun dancer, there was plenty of room in the engine compartment and a 120v receptacle near by, I thought i could install the inverter and back feed the 120v receptacle to power the rest of the boat with 120v power. Seems i'm wrong, when i turn on the power the receptacle that i backfed, has power to that socket, but no A/C power to the rest of the boat, am i missing something?

Hi again everybody, thanks for the tips,