inverter

[okelley]

If a boat has an inverter (2000 watt) Does that mean I can run the AC off the running motor, either while cruising or while at anchor, in neutral? Would an inverter mean I didn't need a genset? Thanks!

[mhanna]

I put an inline 1000W inverter on my boat. Basically it goes inline right before the AC circuit breakers. When connected to shore power everything goes right through the Inverter and everything functions normally. When away from shore power I flip on the inverter and it powers up the whole AC circuit panel, you can then go use whatever 110 outlet (microwave,ect) you want. It has come in handy to run the microwave, use the 110 to run a tv, ect...
You do not need the engine running to do this BUT you have to be careful not to run down the battery so much that you cant start it later. Most good inverters warn of low battery's, but unless I am just running something for a few minutes while standing there I switch to 1 or the other battery so I can always start the boat later.

Notes: I would buy a bigger unit next time.... my microwave draws 800W and while it works you cant do anything else. If you walk into a store to buy a new micro, they draw even more...
Also, dont cheap out on the 12V wiring when installing. Inverters just change power from 12v to 120v, simple math shows they draw alot of 12v current. When running small microwave (1000w/12v= 83Amps). Short and large cables are needed.

Good luck, I installed this on a 28TE. If you interested I could take some pics of the install, let me know.

Matt

I just happen to be heading out on a friends boat today and it chilly out, I usually bring some microwave soup, but NO I cant do this cause he does not have one of these things (cheap guy)

[okelley]

Thanks for the info. Let me ask you this: what does a large output alternator do? And how can I run an airconditioner, either while underway or on the hook? It gets really hot, and stays that way for a long time, down in FL, where I'm used to cruising. Can I run an air conditioner off my boat motor?

[jcollins]

I have a Xantrex 2000 inverter on my boat as well. I use it for quick microwave, small coffee pot, lights, TV, etc.. It will not run my carry-on air conditioner.
I don't know about trying to run your AC unit with it. Obviously it would kill your battery in no time, but keeping the engine running is an idea.

Do you want to be at anchor with your engine running for long periods of time?

What is the long term affect on the alternator? You should contact the manufacturer of your inverter.

If you don't want to install a genset, consider a Honda portable. I use one. Many boaters do. I keep it on the swim platform or on the bow depending on activity around us. I don't run it at night if other boaters are anchored nearby.
They are quiet and efficient. But, keep your CO detecter up to date.

[Mariner]

Whether or not an inverter will power your air conditioning will depend entirely on the power demand of your air conditioner. In most cases, an A/C will draw far more power than an inverter can provide. A 2000 watt inverter can only supply a theoretical 16 amps. We have dual A/C units, and each one draws about 20 amps on start-up. When connected to a 30 amp shorepower circuit, I have to be careful to power them on separately to avoid throwing the breaker.

Most boats are wired such that it is impossible to run the A/C off the inverter. And even a high output alternator doesn't put out much power when you're idling. Nowhere near the 170 amps it would require to power a 2,000 watt inverter. So, you'd have to throttle up the engine to nearly full speed to keep the batteries from drawing down. An 8D battery (not sure what you have), is rated for about 250 amp-hours. This means, in theory, you'd be able to run the A/C via the inverter for about an hour and a half before the battery was completely dead. In practice, it would drop below the voltage cutoff and stop inverting in a matter of minutes.

Of course, all of these numbers are theoretical. They assume 100% efficiency of the inverter (which is far from reality), and no voltage drop over the cable runs. The reality is that as soon as you fired up the A/C, the inverter would probably trip it's breaker and shut off.

In theory, a person could install enough batteries and a big enough inverter to power their A/C without a generator, through the night or an afternoon cruise. However, the weight of the batteries and the inherrent inefficiency of the inverting process means that it's simply more efficient from an energy standpoint to have a generator. Generators can produce sufficient amps to power an A/C unit and sip only a minimal amount of fuel.

Inverters are great when you want to run the microwave for a minute or two to heat up a snack underway or plug in a laptop to check your email, due to the fact that they are scalable in terms of their energy consumption. But when it comes to big, constant loads, it pays to cut out the intermediate step and just convert your fuel directly in to AC power.

When we first bought our boat, I was not that excited about the generator. But I've been converted. It uses minimal fuel and provides a constant supply of power. When I'm fishing, I just leave it running. If I want to stop and drift for a while, I can shut down the main engine without any worry of drawing down the batteries. I can leave the A/C on without worry. And at the end of the day, the fuel use is negligible. I don't even notice it. If you're spending multiple nights anchored out in one location, where you don't run the engine during the day to move, it's more efficient to charge the batteries using the generator and a charger than by idling the main engine, by the simple virtue of the fact that it's a smaller engine running at it's optimal speed, as opposed to a larger engine, with lots of mechanical friction, running at far below it's optimal speed. It takes longer, but it uses less fuel.

[Russell]

Matt: I would appreciate seeing pictures of your inverter installation. I never thought about using it underway but a hot cup of soup or coffee would be just the thing during January striper fishing.

[okelley]

Thanks very much for the info. I didn't know a generator was more efficient than the boat motor for running electrics. Very helpful!

[okelley]

Russ, I'm (obviously) no expert, but I bought a little inverter for under $100 that I plugged into a 12v (cigarette lighter) outlet on my sailboat, and could run small (coffee grinder) type electric appliances.

[RobS]

I just happen to be heading out on a friends boat today and it chilly out, I usually bring some microwave soup, but NO I cant do this cause he does not have one of these things (cheap guy)

You are correct - That inverter would have come in handy today so I could have made you vacuum up all of your donut crumbs!