I see a lot of adds for sailboats that include inverters. I know inverters change DC to Ac, but if you have shore power, why would you need an inverter.
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A/C power at sea
We have two inverters on board. We use them to power light use A/C powered electronics onboard when on the hook. Mostly a radio or camera battery chargers and my night-time breathing machine. You cannot run large draw electronics from your batteries, at least for very long, so, your air-conditioner will have to run off your generator, etc.
We have two inverters on board. We use them to power light use A/C powered electronics onboard when on the hook. Mostly a radio or camera battery chargers and my night-time breathing machine. You cannot run large draw electronics from your batteries, at least for very long, so, your air-conditioner will have to run off your generator, etc.
Hi Richard.
Around these parts, we call that question a newbie post. Are you planing to get into sailing/cruising? If so, you came to the right place!
Around these parts, we call that question a newbie post. Are you planing to get into sailing/cruising? If so, you came to the right place!
FRED!
Yes, I am getting into to sailing. I have been reading here for a short while. I used to have an electric convertor in my '66 VW to change 6 volts to 12 volts so I could play my 8-track (I am older). I have read about shore power to ooperate boat systems and using battery power under sail. I am confused about inverters and where do they come into play. WHat are they used for and what systems do they work with. My friend has a CAt22 and he does not have one. Thanks for all the info and what more hopefully will come.
Yes, I am getting into to sailing. I have been reading here for a short while. I used to have an electric convertor in my '66 VW to change 6 volts to 12 volts so I could play my 8-track (I am older). I have read about shore power to ooperate boat systems and using battery power under sail. I am confused about inverters and where do they come into play. WHat are they used for and what systems do they work with. My friend has a CAt22 and he does not have one. Thanks for all the info and what more hopefully will come.
Electricity and Inverters 101
DC (Direct Current) is what you find in a car (6 volts like in your old VW, but almost all cars now run on 12 volts). The 'direct' means that the current always flows in ONE direction. By the way, 'Volt' was a famous electrical guy from way back. AC (Alternating Current) is what you have in your house, likely supplied by the power company. In America and some other parts of the world, it is 110 to 120 volts, most of the world uses 220 volts. (110 volts is safer, but 220 is more efficient/cheaper to transmit). The 'alternating' means that the current actually CHANGES DIRECTIONS very rapidly - in America, it's 60 times per second, the rest of the world generally uses 50. The number of times the current changes directions is known as the frequency, and is also known as 'Hertz', after the man who, if I recall, discovered the phenomonon. That's the basics - you can study this all the way up through a Phd.
Your boat will have batteries to start the engine, power the lights, pumps and other common boat systems. The batteries will be 12 volts in almost all cases. Many people do just fine with only a 12 volt battery, however some wish to bring other appliances or systems aboard. For instance, a hair dryer, a TV, a (non-laptop) computer, etc. These require 120 volts of AC power. That's where the inverter comes in. I could get quite technical (and will, if you like) but the simple explanation is that it is a 'black box' that hooks up to your batteries, takes in 12 volts DC, and puts out 120 volts AC. When the inverter is turned on, you can plug your AC stuff into it and use them. Inverters are rated in WATTS, a measure of power named after James Watt, another famous electrical guy. As an example, your small TV might consume 50 watts, but a hair dryer uses up to 1800 watts. So you have to size your inverter for the devices and systems you expect to use it for. Inverters consume some power themselves when they are on, so 'sonofasailorsailing' might have 2 different size inverters - a small one for radios, computers and stuff, and a BIG one for when he fires up his monster stereo or hair dryer. Hopefully that explains some of what you're interested in. Please feel free to ask questions. Also, don't be put off by the chatter that occurs in and around these threads.... a lot of us are old friends...... or new friends. Welcome to sailing! Cheers, Bob s/v X SAIL R 8
DC (Direct Current) is what you find in a car (6 volts like in your old VW, but almost all cars now run on 12 volts). The 'direct' means that the current always flows in ONE direction. By the way, 'Volt' was a famous electrical guy from way back. AC (Alternating Current) is what you have in your house, likely supplied by the power company. In America and some other parts of the world, it is 110 to 120 volts, most of the world uses 220 volts. (110 volts is safer, but 220 is more efficient/cheaper to transmit). The 'alternating' means that the current actually CHANGES DIRECTIONS very rapidly - in America, it's 60 times per second, the rest of the world generally uses 50. The number of times the current changes directions is known as the frequency, and is also known as 'Hertz', after the man who, if I recall, discovered the phenomonon. That's the basics - you can study this all the way up through a Phd.
Your boat will have batteries to start the engine, power the lights, pumps and other common boat systems. The batteries will be 12 volts in almost all cases. Many people do just fine with only a 12 volt battery, however some wish to bring other appliances or systems aboard. For instance, a hair dryer, a TV, a (non-laptop) computer, etc. These require 120 volts of AC power. That's where the inverter comes in. I could get quite technical (and will, if you like) but the simple explanation is that it is a 'black box' that hooks up to your batteries, takes in 12 volts DC, and puts out 120 volts AC. When the inverter is turned on, you can plug your AC stuff into it and use them. Inverters are rated in WATTS, a measure of power named after James Watt, another famous electrical guy. As an example, your small TV might consume 50 watts, but a hair dryer uses up to 1800 watts. So you have to size your inverter for the devices and systems you expect to use it for. Inverters consume some power themselves when they are on, so 'sonofasailorsailing' might have 2 different size inverters - a small one for radios, computers and stuff, and a BIG one for when he fires up his monster stereo or hair dryer. Hopefully that explains some of what you're interested in. Please feel free to ask questions. Also, don't be put off by the chatter that occurs in and around these threads.... a lot of us are old friends...... or new friends. Welcome to sailing! Cheers, Bob s/v X SAIL R 8
As noted, the inverter boosts 12 to 120V
It is for when you are away from shorepower that it comes in handy if you have 120 volt appliance, as Bob noted, like battery chargers for rechargeable batteries, too. Some inverters are separate, some are combined with chargers in one neat (albeit bulky) package. If you have no use for 120 V things once away from shorepower, then you don't need one. Many boats also come with hot water heaters that use either engine heat to heat the water, or an electric resistance coil to heat it when plugged into shorepower. Some use large inverters to use the electricity, but it puts a tremendous load on the batteries (12V) and is most often used only when running the engine. It's not really a good thing to do, although I must admit I've tried it a couple of times when I absolutely needed a hot shower!!! (as recommended by crew) Your boat, your choice, but it is a nice thing to have. Also need to make sure the inverter can NEVER come one when shorepower is available. The combined units do it with an internal switch, individual separate inverters need a special switch to make sure that never happens.
It is for when you are away from shorepower that it comes in handy if you have 120 volt appliance, as Bob noted, like battery chargers for rechargeable batteries, too. Some inverters are separate, some are combined with chargers in one neat (albeit bulky) package. If you have no use for 120 V things once away from shorepower, then you don't need one. Many boats also come with hot water heaters that use either engine heat to heat the water, or an electric resistance coil to heat it when plugged into shorepower. Some use large inverters to use the electricity, but it puts a tremendous load on the batteries (12V) and is most often used only when running the engine. It's not really a good thing to do, although I must admit I've tried it a couple of times when I absolutely needed a hot shower!!! (as recommended by crew)
Your boat, your choice, but it is a nice thing to have. Also need to make sure the inverter can NEVER come one when shorepower is available. The combined units do it with an internal switch, individual separate inverters need a special switch to make sure that never happens.Inverters
One thing you should be aware of. An appliance that is rated at 1500 watts, is a not a major consumer of power in your house. But on the boat, it is a lot. You divide the watts by by the volts to get the amps. it draws. So a 1500 watt hair dryer in you house draws in the neighborhood of 15 amps. But when running off a 12 volt battery, it is going to draw almost 150 amps. That is a huge battery drain. So, figure what you want to run that you would require an inverter for, and figure out the wattage and the amp draw on the batteries. Keep it as low as possible. I have a 1200 watt and a 300 watt inverter on my boat. Mostly use the 300 as it will charge the rechargable batts. and run my laptop and is a simple plug in. I would not even consider trying to run the water heater from an inverter, but am installing a home made refigeration unit that will run off the larger one. It will draw about 20 amps. and hopefully will only have to run two or three hours a day max. If your just planning on things like a laptop, recharging the rechargable batteries, a small inverter in the 300 watt range should do you nicely.
One thing you should be aware of. An appliance that is rated at 1500 watts, is a not a major consumer of power in your house. But on the boat, it is a lot. You divide the watts by by the volts to get the amps. it draws. So a 1500 watt hair dryer in you house draws in the neighborhood of 15 amps. But when running off a 12 volt battery, it is going to draw almost 150 amps. That is a huge battery drain. So, figure what you want to run that you would require an inverter for, and figure out the wattage and the amp draw on the batteries. Keep it as low as possible. I have a 1200 watt and a 300 watt inverter on my boat. Mostly use the 300 as it will charge the rechargable batts. and run my laptop and is a simple plug in. I would not even consider trying to run the water heater from an inverter, but am installing a home made refigeration unit that will run off the larger one. It will draw about 20 amps. and hopefully will only have to run two or three hours a day max. If your just planning on things like a laptop, recharging the rechargable batteries, a small inverter in the 300 watt range should do you nicely.
I use mine
For the microwave,charging cell phones,laptop,handheld vhf and new this year is the flat screen tv. I only turn it on when I need it cause as soon as you disconnect shore power it continues to send 125 volts to all wall receptacles and there is some small load on it.
For the microwave,charging cell phones,laptop,handheld vhf and new this year is the flat screen tv. I only turn it on when I need it cause as soon as you disconnect shore power it continues to send 125 volts to all wall receptacles and there is some small load on it.
Inverter
I use a lap top for navigation, so I do like to be able to recharge the computer underway. I also use it to charge my hand held or my ipod. Very modest demands so I picked up an under $50 inverter at the hardware - 300 watts I think - and it has served my anchorage/sailing needs quite well.
I use a lap top for navigation, so I do like to be able to recharge the computer underway. I also use it to charge my hand held or my ipod. Very modest demands so I picked up an under $50 inverter at the hardware - 300 watts I think - and it has served my anchorage/sailing needs quite well.
Thanks....but more please
Wow and thanks. Bob, inverters 101 was great. I understand some basics, I am just lost as it applies to sailboats and their application. So, if I am looking at a boat that has a 2500 inverter, I can assume it puts out 2500 watts, and could be away from shore power to power a microwave, or coffee maker, or tv. BUT, it would eat up a lot of battery power to provide for these appliances. How could it charge the batteries it is sucking power from? This is what boggles my mind. You guys are a lot of help. Please do not abandon me.
Wow and thanks. Bob, inverters 101 was great. I understand some basics, I am just lost as it applies to sailboats and their application. So, if I am looking at a boat that has a 2500 inverter, I can assume it puts out 2500 watts, and could be away from shore power to power a microwave, or coffee maker, or tv. BUT, it would eat up a lot of battery power to provide for these appliances. How could it charge the batteries it is sucking power from? This is what boggles my mind. You guys are a lot of help. Please do not abandon me.
The other side of the story
You need an inverter to keep the admiral happy. hairdryer (I wish I had hair to dry), microwaves so she doesn't have to slave over a hot stove while on the boat, blender for the frozen dacorys (this one makes everybody happy) and a slew of wall warts for recharging the various batteries on hand held devices. If you can convince your admiral that she look fabulous without blown dry hair you can get a really small inverter to handle everything else. If you can't then you should get at least a 2000 watt model as most hair dryers suck up electricty at the rate of 1500 watts.
You need an inverter to keep the admiral happy. hairdryer (I wish I had hair to dry), microwaves so she doesn't have to slave over a hot stove while on the boat, blender for the frozen dacorys (this one makes everybody happy) and a slew of wall warts for recharging the various batteries on hand held devices. If you can convince your admiral that she look fabulous without blown dry hair you can get a really small inverter to handle everything else. If you can't then you should get at least a 2000 watt model as most hair dryers suck up electricty at the rate of 1500 watts.
Battery charging
There are several ways; run the engine so the alternator can do it buy a solar panel and let the sun do it (lots slower however) buy a wind turbine and let the wind do it (faster than solar but not much, does work at night but not in that snug little anchorage out of the wind however) or buy an AC genset. It can charge your batteries (vis the shore power battery charger) and give you AC current for anything else And the rub fast recharge is noisy slow recharge is not Welcome aboard
There are several ways; run the engine so the alternator can do it buy a solar panel and let the sun do it (lots slower however) buy a wind turbine and let the wind do it (faster than solar but not much, does work at night but not in that snug little anchorage out of the wind however) or buy an AC genset. It can charge your batteries (vis the shore power battery charger) and give you AC current for anything else And the rub fast recharge is noisy slow recharge is not Welcome aboard
Law of Convservation of Energy
I can see how you got confused by the post explaining about a combination battery charger/inverter. These units can function as Either a battery charger when you are plugged into the dock, OR an inverter when on the battery bank. Sorry but until we can repeal the Law of Conservation of Energy we can't charge a battery bank with the power we are drawing from it. I hear the Congress is looking into it as a solution to global warming though and a resolution is due out of committee any day.
I can see how you got confused by the post explaining about a combination battery charger/inverter. These units can function as Either a battery charger when you are plugged into the dock, OR an inverter when on the battery bank. Sorry but until we can repeal the Law of Conservation of Energy we can't charge a battery bank with the power we are drawing from it. I hear the Congress is looking into it as a solution to global warming though and a resolution is due out of committee any day.
Richard
It doesn't charge your batterys,you have to start the engine or wait to get back to shore power and recharge the batterys. The charging system is a whole other story but you need a good system from the engine and from shore power to keep the batterys healthy.
It doesn't charge your batterys,you have to start the engine or wait to get back to shore power and recharge the batterys. The charging system is a whole other story but you need a good system from the engine and from shore power to keep the batterys healthy.
It does get confusing, richard. Here's Battery 101
Sailboat power systems quickly get complex, and almost all sailboat owners have to be their own designer, installer and maintainer of just about everything on their boat, because none of us ever won the lottery..... 'cept Fred, I reckon. The 'base of the pyramid' for sailboats is the battery - they come in various sizes, and types, but for now let's just think of a car battery, sitting in the bottom of your boat. When you're at the dock, you can use a Battery Charger to charge the battery. This will hook into shore power, which is the (usually yellow) cord that plugs into the city power on the dock. The Battery Charger will keep your battery all charged up as long as you are in the slip and hooked up to shore power. When you leave the dock, you have to unhook the shore power, so you need something else to charge the battery. The first option, for most sailboats, is the engine - most engines have an alternator, just like a car does. This includes just about all inboard engines (most are diesel on sailboats) and some outboards as well. The alternator puts out DC voltage (13 to 14 volts, but don't worry that it's over 12 volts, we'll get to that later) right to the battery and charges it. That's fine, as long as your engine is running, but we didn't buy a sailboat to run the engine, did we? Let's say you're sailing on a lake, mostly just for the day. You won't really worry about draining your battery, because you know it's fully charged when you leave the dock, you won't be using much power while you're sailing, and you know you can either run your engine for a while if you need to, or that you'll be back at the dock in the evening to plug into shore power. OK, if you're going to stay out overnight (or longer) you've got to 'cut the cord' and be able to charge your battery without shore power. Your engine alternator works, but it's noisy and it takes a while and diesel keeps getting more expensive, so now you're into your first 'boat trade-off'... (did anybody mention that EVERYTHING on a sailboat is a trade-off?) One solution is: more batteries. Batteries are usually rated by amp-hours - that is, the number of amps a battery can deliver for one hour. Now a LITTLE math: Watts = Volts x Amps So, 1 amp at 12 volts = 12 watts. Your hair-dryer takes 1800 watts, so: 1800 watts = 12 volts x 150 amps. A battery roughly the size of the one in a car will produce about 75 amp-hours. You're not stuck with the 'one hour', so it can give you: 1 amp for 75 hours 25 amps for 3 hours 300 amps for 15 minutes (.25 hours) The trade-off is that batteries are heavy, costly, and they wear out with distressing rapidity when used a lot. So you need to strike a balance between carrying more batteries, charging them more often, and using less electricity aboard. Finding that balance is a challenge, and it is a continuing one for any sailor who spends a lot of time away from shore power. As Bill Roosa mentioned, there are ways other than an engine alternator to charge your battery: solar, wind, a dedicated generator.... you can even buy a water generator - that's a propellor that you drag behind your boat that spins when you sail and turns a shaft that turns a generator that produces electricty. Continuing with the trade-off theme: Solar is VERY expensive up-front and a challenge to keep pointed at the sun to get maximum output from. Wind generators are noisy, and, unbelievably, only work when there is enough wind and NOT TOO MUCH WIND! Towed generators only work when you are sailing and slow your boat down. Generators are expensive, can be noisy and drink fuel. In summary, if you are planning to be a day-sailor, or weekend cruiser (even extending to week-long trips), or even living aboard at the dock, you'll probably be looking at charging your battery with shore power and engine alternator. Your trade-off study will involve estimating your power consumption (everything from the hair-dryer to your anchor light [12 hours x .5 amp/hour = 6 amp/hours per day when you're anchoring out]), figuring out how much engine running time you can expect (mostly when entering/leaving an anchorage - you don't want to run your engine JUST to charge your battery because that's bad for diesels), and then making sure you have enough batteries available to satisfy your needs. This often involves multiple batteries - some boats have 10 or more. Most sailors keep 1 battery separate from their 'house' system just to start their engine as a safety measure. Cheers, Bob s/v X SAIL R 8
Sailboat power systems quickly get complex, and almost all sailboat owners have to be their own designer, installer and maintainer of just about everything on their boat, because none of us ever won the lottery..... 'cept Fred, I reckon.
The 'base of the pyramid' for sailboats is the battery - they come in various sizes, and types, but for now let's just think of a car battery, sitting in the bottom of your boat. When you're at the dock, you can use a Battery Charger to charge the battery. This will hook into shore power, which is the (usually yellow) cord that plugs into the city power on the dock. The Battery Charger will keep your battery all charged up as long as you are in the slip and hooked up to shore power. When you leave the dock, you have to unhook the shore power, so you need something else to charge the battery. The first option, for most sailboats, is the engine - most engines have an alternator, just like a car does. This includes just about all inboard engines (most are diesel on sailboats) and some outboards as well. The alternator puts out DC voltage (13 to 14 volts, but don't worry that it's over 12 volts, we'll get to that later) right to the battery and charges it. That's fine, as long as your engine is running, but we didn't buy a sailboat to run the engine, did we? Let's say you're sailing on a lake, mostly just for the day. You won't really worry about draining your battery, because you know it's fully charged when you leave the dock, you won't be using much power while you're sailing, and you know you can either run your engine for a while if you need to, or that you'll be back at the dock in the evening to plug into shore power. OK, if you're going to stay out overnight (or longer) you've got to 'cut the cord' and be able to charge your battery without shore power. Your engine alternator works, but it's noisy and it takes a while and diesel keeps getting more expensive, so now you're into your first 'boat trade-off'... (did anybody mention that EVERYTHING on a sailboat is a trade-off?) One solution is: more batteries. Batteries are usually rated by amp-hours - that is, the number of amps a battery can deliver for one hour. Now a LITTLE math: Watts = Volts x Amps So, 1 amp at 12 volts = 12 watts. Your hair-dryer takes 1800 watts, so: 1800 watts = 12 volts x 150 amps. A battery roughly the size of the one in a car will produce about 75 amp-hours. You're not stuck with the 'one hour', so it can give you: 1 amp for 75 hours 25 amps for 3 hours 300 amps for 15 minutes (.25 hours) The trade-off is that batteries are heavy, costly, and they wear out with distressing rapidity when used a lot. So you need to strike a balance between carrying more batteries, charging them more often, and using less electricity aboard. Finding that balance is a challenge, and it is a continuing one for any sailor who spends a lot of time away from shore power. As Bill Roosa mentioned, there are ways other than an engine alternator to charge your battery: solar, wind, a dedicated generator.... you can even buy a water generator - that's a propellor that you drag behind your boat that spins when you sail and turns a shaft that turns a generator that produces electricty. Continuing with the trade-off theme: Solar is VERY expensive up-front and a challenge to keep pointed at the sun to get maximum output from. Wind generators are noisy, and, unbelievably, only work when there is enough wind and NOT TOO MUCH WIND! Towed generators only work when you are sailing and slow your boat down. Generators are expensive, can be noisy and drink fuel. In summary, if you are planning to be a day-sailor, or weekend cruiser (even extending to week-long trips), or even living aboard at the dock, you'll probably be looking at charging your battery with shore power and engine alternator. Your trade-off study will involve estimating your power consumption (everything from the hair-dryer to your anchor light [12 hours x .5 amp/hour = 6 amp/hours per day when you're anchoring out]), figuring out how much engine running time you can expect (mostly when entering/leaving an anchorage - you don't want to run your engine JUST to charge your battery because that's bad for diesels), and then making sure you have enough batteries available to satisfy your needs. This often involves multiple batteries - some boats have 10 or more. Most sailors keep 1 battery separate from their 'house' system just to start their engine as a safety measure. Cheers, Bob s/v X SAIL R 8
How'd I miss this one?
Richard, try this, scroll down to Electrical and read away: http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorListView?storeId=10001&langId=-1&catalogId=10001
Richard, try this, scroll down to Electrical and read away: http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorListView?storeId=10001&langId=-1&catalogId=10001
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