Inverter power - overly simplified plan?

[k9medic]

I have been wanting to add an inverter and set of batteries to power some of my 110V items and have read through a bunch of threads on this forum from those who have added them. Unfortunately, most of these additions come at a substantial cost.

In an effort to reduce costs, maybe I have over simplified things in my mind but here is what I was thinking -

My Marvel fridge and freezer is really what I want to power. These show they are rated at 115 volts for 3 amps which makes them 345 watts per appliance or 700 watts total to be safe.

Could I buy a 3500 watt inverter like this http://www.amazon.com/gp/product/B0...uct_details?ie=UTF8&me=&qid=1423863681&sr=8-3

along with some golf cart deep cell batteries and wire the inverter into my AC panel? I was thinking of adding a solar charger to keep the batteries topped off.


In short, why would this not work?

 

[CougarCruiser]

are you saying you'll change over your 'house bank' to be golf cart batteries? That's a very common upgrade with minimal cost. Costco batteries are cheap and generally fairly positively recommended. That's a great starting point.


That inverter might work fine for you (not marine rated, but that's ok if you are ok with the risk). Where you run into questions is your statement of 'wiring into your AC panel'. What's your thought about that? You'll have to have some sort of switching between shore power/generator/your inverter. Are you going to light up the entire panel, or just a couple of circuits?


It's not as easy as 'just wiring it up'. you have to 'deal with it' alongside your other AC power providers.... backfeeding = bad

 

[k9medic]

I was thinking of adding 2-3 batteries that are being charged via the solar panel and attaching the inverter to those batteries.

I'm not really sure how to "plug" the inverter into the panel but I would think I could run the inverter power to a few of the circuits like the fridge and freezer.

 

[Westie]

Your going to need a bigger boat to hold all the solar panels that you will need to keep those batteries charged.

 

[SloBurn]

Nope, won't work. Inverter is overrated for your usage. But I would add a switch to your AC panel that will isolate inverter from shore power. Then when your unplugged from shore power just throw switch to use inverter to run your AC panel.

 

[BryanOnTheBay]

In order to wire it in, you would need a transfer switch. This would disconnect the shore power before connecting the inverter. One thing to remember with this inverter is that it is a modified sine wave inverter, and I seem to remember that they don't play well with refrigerators, but don't quote me on that.

Bryan

 

[k9medic]

An 80W solar panel is approximately 36"x26" which will fit on top of my ft cabin with no problem.

If I am doing my math correctly, on an average sunny day in Florida, I should be able to "charge" for at least 8 hours. If I had two 80W panels then I would have 8 x 160 =1280 watts per day of energy.

Using the math from above of 700 watts that should be enough right?

 

[Henry Boyd]

I was thinking of adding 2-3 batteries that are being charged via the solar panel and attaching the inverter to those batteries.

I'm not really sure how to "plug" the inverter into the panel but I would think I could run the inverter power to a few of the circuits like the fridge and freezer.

No insult intended, but if you don't know how to wire it up, the project is beyond your skill level.

Solar panels will maintain batteries, they won't recharge deeply discharged ones as would be found in an inverter operation.

Henry


Sent from my iPad using Tapatalk HD

 

[Westie]

An 80W solar panel is approximately 36"x26" which will fit on top of my ft cabin with no problem.

If I am doing my math correctly, on an average sunny day in Florida, I should be able to "charge" for at least 8 hours. If I had two 80W panels then I would have 8 x 160 =1280 watts per day of energy.

Using the math from above of 700 watts that should be enough right?

at 8 hours per day with 2 80 Watt panels and about 80% conversion and charge efficiency (which is probably high) you will get about 1024 watt hours

you appliances take 700 watts when running. Lets say they run about 25% of the time and you converter is about 80 % efficient.
The energy from the battery for a days use is is 700 *.25 / 0.8 * 24 = 5250 Watt hours so you are short by a factor of about 5

 

[NorCal Boater]

I don't believe that inverter is marine rated.

Here's what you need....
http://inverterservicecenter.com/Xantrex-806-1810

I had a similar situation in my old '89 340da. I had replaced my dead Norcold for a GE fridge that was 110volt only. The boat had 3 batteries. Two starting batteries and one house battery.

The Xantrex 1800 inverter will give you 1800 watts of power. It has pass-through capabilities, a built in transfer switch and a wired remote. I replaced one of my starting batteries with 2, 6 volt golf cart batteries from Costco. The batteries were charged by the engine alternator when underway and by the charger when plugged in to shore power or on generator. The deep cycle golf carts are not the best way to start a motor but I did have the battery crossover if needed. I had the inverter wired to 2, 110 volt outlets through the appropriate breakers; the fridge (GE 110v only) and the outlet for my TV/Blu-ray player. With the built-in transfer switch, the inverter senses the absence of a 110v source (shore power or generator) and switches to invertor mode and pulled from the golf cart batteries. The remote will tell you your battery voltage and the system has built-in protection. If the battery voltage drops below a certain point it shuts down to save the batteries. You are also able to turn things on and off manually.

I mounted the inverter in a space behind my electrical panel and placed the remote in a blank area at the panel where I had easy access. It is best to have the invertor as close to the batteries as possible to minimize the cable run and subsequently the cable size. As it was, I had to use 4/0 battery cable. ($$$) I installed a fuse in the positive cable from the battery to the inverter. I hard-wired from the inverter output to the 2 appropriate breakers on my breaker panel (fridge & TV). I added a breaker to the panel for the 110v input on the inverter for the pass-through feature. With the 110v pass-through those 2 circuits got house 110v when the inverter was off and 110v from the batteries /inverter when on.

Looking on line I've seen the inverter for as low as $320. The batteries were about $80 each. Due to my space restrictions I needed a battery box that held the batteries end-to-end. That box was $100 with a screw-on lid. The battery cable is the killer. West Marine sells 4/0 at $13/foot. It can be found much cheaper on eBay. The breaker and additional cabling was less that a 100 bucks.

This is by far you cheapest and safest route to go. I was very limited on space for batteries which is why I replaced one of the starting batteries. If you have more room you can just add this setup assuming you have capacity in your charger to take on say, at least one more 12 battery. (2, 6 volt) Or, you could replace your current house battery for 4 golf carts for the house, wire in the inverter and your problem is solved. My big boat has 6 golf carts for the house wired through a 3000 watt Magnum Inverter/Charger.

SO that's what I did and it worked great. Please let me know if you have any questions.

 

[k9medic]

No insult intended, but if you don't know how to wire it up, the project is beyond your skill level.

Sent from my iPad using Tapatalk HD

None taken. This is not beyond my skill level it's simply something that I have been looking at from several directions and I want to make sure I'm not over thinking something which I have a tendency to do.

 

[ktcanuck]

I have a 96 420AC, 3kw Xantrex, 6 Lifeline AGM 6v 220AHr batteries, 2 140W Kyocera Solar panels and a Morningstar MPPT controller. Two 110V lines are wired from the panel through the inverter and back to the panel. The inverter and batteries are mounted under the port side sofa and vents into the cavity behind.

PM me and I will send you diagrams of the panel wiring, inverter/ battery location, battery bank wiring design including specs for manufacture and pics of solar panel location. Don't PM me if you think this is cheap!

It all works seamlessly.

 

[k9medic]

I have a 96 420AC, 3kw Xantrex, 6 Lifeline AGM 6v 220AHr batteries, 2 140W Kyocera Solar panels and a Morningstar MPPT controller. Two 110V lines are wired from the panel through the inverter and back to the panel. The inverter and batteries are mounted under the port side sofa and vents into the cavity behind.

PM me and I will send you diagrams of the panel wiring, inverter/ battery location, battery bank wiring design including specs for manufacture and pics of solar panel location. Don't PM me if you think this is cheap!

It all works seamlessly.

PM sent. Thank you!

 

[peachypete82]

Nope, won't work. Inverter is overrated for your usage. But I would add a switch to your AC panel that will isolate inverter from shore power. Then when your unplugged from shore power just throw switch to use inverter to run your AC panel.

Has anyone every considered using the guts of a UPS for this automatic switching? UPS systems for computers etc take mains, and when mains drops off it kicks in the invertor from the batteries, and when mains it back on, it goes automatically back into charge mode and puts the AC direct through and charges the batteries... i guess this would be the same as purchasing an inverter charger? i just like the way a simple UPS already does exactly what us boaties want..