Best inverter for the buck

[prroots]

I'm in the process of installing a 400 Watt solar system with MPPT controller. This system, hopefully, justifies the installation of an inverter. It should be capable of running our microwave. I would very much appreciate recommendations. It should have high efficiency, high reliability, and very low drain when no loads are connected. As the title, indicates, price is definitely an important factor. I don't want a combo inverter/charger since I already have a nice charger installed.
Pete

 

[Ed Schenck]

Sure as anyone recommends something then ten others will tell you why you shouldn't. With that caveat I will say my Heart Freedom 20 has been bullet proof. It was on the boat when I bought her in 1998. So no easy way of knowing the age. If I had to replace it then it would be with a like model from Xantrex. It is a 2000 watt inverter/100 amp charger and runs the coffee maker and 1000 watt microwave at the same time(before I bought my French Press ).

 

[Stu Jackson]

Before you buy you need an energy budget. How big is your house bank, but more importantly, what do you need to run on AC on the boat when away from shorepower. Of course, you can use the AC appliances one-by-one, too. The size of your AC load may determine which inverter you buy.

West Marine offers different brands. Others have reported that these are good, too: http://www.tripplite.com/en/products/power-inverters-chargers.cfm

A Google search will give you a bunch of options. Do you already have a shortlist?

 

[Don S/V ILLusion]

It 's all about your needs. Pure sine wave v. modified v. junk wave all vary in price accordingly. Also, as microwaves vary in demand from a few hundred watts up, it depends on need as well there. Most people's perception on quality is a product of limited experience in that if one goes bad, the conclusion is the company must make bad products.
I don't recall but Practical Sailor may have compared inverters and is worth checking their comments which would be more objective than a couple of opinions here.

 

[prroots]

Before you buy you need an energy budget. How big is your house bank, but more importantly, what do you need to run on AC on the boat when away from shorepower. Of course, you can use the AC appliances one-by-one, too. The size of your AC load may determine which inverter you buy.

West Marine offers different brands. Others have reported that these are good, too: http://www.tripplite.com/en/products/power-inverters-chargers.cfm

A Google search will give you a bunch of options. Do you already have a shortlist?

I just checked our microwave. It draws 1260 watts so we should be looking for an inverter in the range of 1500 watts. I'm guessing that most other loads we have are less. We are happy to discipline ourselves according to which loads can run together, etc.
Pete

 

[prroots]

I see a ton of inverters on eBay and elsewhere that have the standard 115 VAC outlets on the end with an on/off switch. Do boat owners generally connect these into their boat AC or use them standalone?
Pete

 

[mitiempo]

Smaller and less expensive inverters only have the outlets on the end. Larger inverters have the ability to be hardwired into the AC system. Most have a pass through. The AC wiring from a breaker on the main AC panel goes to the inverter AC in and the AC out goes ideally to a sub-panel that includes only those items you wish to power with the inverter - usually AC outlets. This does 2 things - it allows outlets to be used both with shorepower and the inverter and also prevents using the inverter with for example a water heater that would deplete the battery bank very quickly. These inverters such as Xantrex, Magnum and others have automatic transfer switches built-in. The inverter is always off when shorepower is connected even if it is on when the shorepower plug is connected to the boat.

Your microwave may need 2000 watts as there is quite a surge when they are first turned on.

 

[prroots]

Smaller and less expensive inverters only have the outlets on the end. Larger inverters have the ability to be hardwired into the AC system. Most have a pass through. The AC wiring from a breaker on the main AC panel goes to the inverter AC in and the AC out goes ideally to a sub-panel that includes only those items you wish to power with the inverter - usually AC outlets. This does 2 things - it allows outlets to be used both with shorepower and the inverter and also prevents using the inverter with for example a water heater that would deplete the battery bank very quickly. These inverters such as Xantrex, Magnum and others have automatic transfer switches built-in. The inverter is always off when shorepower is connected even if it is on when the shorepower plug is connected to the boat.

Your microwave may need 2000 watts as there is quite a surge when they are first turned on.

Thanks. Say an inverter feeds just the AC outlets. What's to prevent the current from back feeding into the main AC panel assuming all breakers on the main AC panel are closed?

For budgetary reasons, I'm interested in one of the cheap true sinewave inverters with the on/off switch and 115 VAC outlets. I wonder how best to feed the AC outlets without, as you say, the risk of feeding battery charger or water heater. The other risk is forgetting to turn it off prior to plugging in shore power. We just don't have the budget right now to afford one of the fancy ones that go to sleep when no load and automatically switch over to shore power when sensed.
Pete

 

[prroots]

This is the most interesting inexpensive true sine wave inverter I've found so far:
Ramsond SunRay Pure Sine Wave Inverters

The Sunray 1500 sells for $239.99 and the remote control costs $39.99. I think the remote is very valuable since the inverter would be mounted in the engine room close to batteries and the remote switch can be located in some other convenient location eg, next to AC panel. Anyone have experience with this company or have other similar ones to recommend?

If not for the budgetary restrictions, the Xantrex ProSine 1800 (806-1802 version) looks very nice:
Power Inverter, Pure Sine Wave Inverter, Marine Inverter, PROsine
It includes a transfer switch to automatically switch from inverter to shore power, but the best price I've seen is $949.
Pete

 

[Stu Jackson]

T I think the remote is very valuable since the inverter would be mounted in the engine room close to batteries and the remote switch can be located in some other convenient location eg, next to AC panel.

Pete, I believe that this is very poor advice. I am aware that Beneteau put their OEM setup batteries at the foot of the companionway on many mid sized models, which essentially puts them in the engine space. Not good for the batteries, due to heat, but that's where they are. Compounding that by placing the delicate parts of an inverter, with its potentially lethal 120V is just a bad idea.

For the sake of a few feet more of 1/0 wiring, please, put your inverter outside the engine space. Please.

 

[Stu Jackson]

Thanks. Say an inverter feeds just the AC outlets. What's to prevent the current from back feeding into the main AC panel assuming all breakers on the main AC panel are closed?

For budgetary reasons, I'm interested in one of the cheap true sinewave inverters with the on/off switch and 115 VAC outlets. I wonder how best to feed the AC outlets without, as you say, the risk of feeding battery charger or water heater. The other risk is forgetting to turn it off prior to plugging in shore power. We just don't have the budget right now to afford one of the fancy ones that go to sleep when no load and automatically switch over to shore power when sensed.
Pete

Pound wise and penny foolish.

Either you wire it into your 120V circuits AND

1. either buy an inverter with an automatic transfer switch in it (I know they make 'em, 'cuz it was discussed here recently) OR

2. install a manual transfer switch so the shorepower and the inverter can NEVER be on at the same time.

If you don't, you'll fry your brand new inverter.

OR

You buy an inverter with the receptacles on it and DO NOT connect the inverter 120V output to your existing on board 120V system.

Them's your choices, but you really need to do it right.

http://c34.org/bbs/index.php/topic,833.0.html

There are other rotary transfer switches available that function like the 8032, believe also made by Blue Sea.

 

[prroots]

Pound wise and penny foolish.

Either you wire it into your 120V circuits AND

1. either buy an inverter with an automatic transfer switch in it (I know they make 'em, 'cuz it was discussed here recently) OR

2. install a manual transfer switch so the shorepower and the inverter can NEVER be on at the same time.

If you don't, you'll fry your brand new inverter.

OR

You buy an inverter with the receptacles on it and DO NOT connect the inverter 120V output to your existing on board 120V system.

Them's your choices, but you really need to do it right.

http://c34.org/bbs/index.php/topic,833.0.html

There are other rotary transfer switches available that function like the 8032, believe also made by Blue Sea.

Thanks, I appreciate the advice. You've motivated me to rethink the situation. I think I figured out a simpler and less expensive solution. One installs an ordinary DPDT (double pole, double throw) switch downstream of the breaker servicing AC outlets. The center (common) tap goes to the AC outlets while the other two sides are AC panel (shore power) and inverter output. Since it's double pole, it simultaneously switches the hot and neutral lines. This solves two important issues:

• inverter can never inadvertently feed water heater, battery charger, etc
• inverter and shore power can never the interconnected.

Did I miss something?
Pete

 

[Bill Roosa]

Ditto Stu's comments. 120 volt AC is not to be trifled with. Your insurance company will be somewhat less than supportive when you burn the boat down and the inspector finds you did not have a transfer switch.
The original post indicated that you where increasing production by 400 watts via solar. I'll assume you have the smallest Microwave obtainable at approx 500 watts and also assume you will only be using it intermittently for a total of 10 minutes per day total.
You can expect to get around 4 hours of "full sun equivalent" from the solar panels or 1600 watt hours --> @ 13.8 volts that would be 116 AH output. Assuming you store this in batteries then use it (not the preferred but typical) you will lose around 10% going in and 10% coming out and then lose another 5% in the inverter so you really only increased your production by 89 AH
The microwave will consume 36 amps when running and for 10 minutes (10/60 hours) that would be 6 amp hours total per day.

I'm thinking you could get by with just a little engine running and save yourself the hassle of the solar install. Diesel is pretty cheap. A stock 53 amp charger would produce the 8 AH needed to recharge the batteries in 9 minutes. That assumes a bulk charge rate as you would not want to charge the batts if they were 90% SOC

You should be good to run the reefer though.

 

[prroots]

Ditto Stu's comments. 120 volt AC is not to be trifled with. Your insurance company will be somewhat less than supportive when you burn the boat down and the inspector finds you did not have a transfer switch.
The original post indicated that you where increasing production by 400 watts via solar. I'll assume you have the smallest Microwave obtainable at approx 500 watts and also assume you will only be using it intermittently for a total of 10 minutes per day total.
You can expect to get around 4 hours of "full sun equivalent" from the solar panels or 1600 watt hours --> @ 13.8 volts that would be 116 AH output. Assuming you store this in batteries then use it (not the preferred but typical) you will lose around 10% going in and 10% coming out and then lose another 5% in the inverter so you really only increased your production by 89 AH
The microwave will consume 36 amps when running and for 10 minutes (10/60 hours) that would be 6 amp hours total per day.

I'm thinking you could get by with just a little engine running and save yourself the hassle of the solar install. Diesel is pretty cheap. A stock 53 amp charger would produce the 8 AH needed to recharge the batteries in 9 minutes. That assumes a bulk charge rate as you would not want to charge the batts if they were 90% SOC

You should be good to run the reefer though.

Thanks for all the input. We were posting at the same moment and I think I came up with a very simple solution to solve the inverter issue (see above posting). With respect to power usage, I should mention that we also have a wind generator. On our previous boat we had the same wind generator and 255 Watts of solar (three 85 watt panels) and were 100% autonomous. Our daily usage averaged 110 Ah with refrigerator/freezer being 50% of the total. Our rather intuitive conclusion is that we will have a bit of excess energy now since we now have 57% more solar output. Also, our diesel only has the stock 40 Amp alternator which rarely puts out more than 30 Amps. I would much rather invest in solar than a hi-amp alternator. Without the solar and without a hi-amp alternator we would be running diesel for quite a few hours each day to keep up.
Pete

 

[Ron20324]

I wonder how best to feed the AC outlets without, as you say, the risk of feeding battery charger or water heater. Pete

If you have duplex/double outlets, you could wire one plug to the AC panel, the other to the inverter.

 

[prroots]

If you have duplex/double outlets, you could wire one plug to the AC panel, the other to the inverter.

Thanks. True, but we'd want all our scarce outlets to be available and besides it would be a lot of work wiring to one side of all our duplex outlets. Finally the microwave plug is difficult to get to and therefore, we don't want to keep changing it
Pete

 

[mitiempo]

Regarding the Sunway inverter - at way less than half what a name brand costs. You get what you pay for. I would buy a good quality modified sine wave inverter before a no-name pure sine wave. Marketing is everything to some and "pure sine wave" is very marketable.

The Xantrex Pro series 1800 watt version is a good choice and includes the auto transfer switch. http://www.xantrex.com/power-products/power-inverters/pro-series-inverters.aspx

If you decide on an inverter without a transfer switch the panel below http://bluesea.com/category/106/88/products/8032 is a good choice. The inverter output goes to one double breaker and the shorepower to the other, the output going to the main panel. Your main panel already has a double pole main breaker - just remove it and add 2 single breakers for spare circuits. You will still have to be cautious not to leave the water heater etc on while using the inverter.

And do not install the inverter near the batteries - the corrosion from charging gases will do it in quickly.

 

[prroots]

Regarding the Sunway inverter - at way less than half what a name brand costs. You get what you pay for. I would buy a good quality modified sine wave inverter before a no-name pure sine wave. Marketing is everything to some and "pure sine wave" is very marketable.

The Xantrex Pro series 1800 watt version is a good choice and includes the auto transfer switch. http://www.xantrex.com/power-products/power-inverters/pro-series-inverters.aspx

If you decide on an inverter without a transfer switch the panel below http://bluesea.com/category/106/88/products/8032 is a good choice. The inverter output goes to one double breaker and the shorepower to the other, the output going to the main panel. Your main panel already has a double pole main breaker - just remove it and add 2 single breakers for spare circuits. You will still have to be cautious not to leave the water heater etc on while using the inverter.

And do not install the inverter near the batteries - the corrosion from charging gases will do it in quickly.

Thanks. Not sure if you saw my inexpensive and simple solution. It prevents inverter from ever being connected to shore power and as a bonus doesn't allow inverter to ever feed battery charger, water heater, etc. Seems a very lot simpler and offers better protection not to mention that I don't have the space to install another panel.
Pete

 

[mitiempo]

I saw the posting. It would work, but I like my solution better.

Many boats have multiple breakers for outlets, I'm surprised yours doesn't. My boat has a breaker for each outlet.

 

[prroots]

I saw the posting. It would work, but I like my solution better.

Many boats have multiple breakers for outlets, I'm surprised yours doesn't. My boat has a breaker for each outlet.

Thanks. I'm always inclined to go with the simplest, most effective and cheapest solution. These forums are great for the ideas expressed and getting one to think about issues and their possible solutions.
Pete