My wife and I just bought our first sail boat: A trailer sailer. We're docked at lake lanier. The boat already has shore power, but I had a question about batteries for anchoring out. We're not the spoiled type, and don't need a microwave or blow drier, but we do want to be able to run our radio and tv (13 inch with dvd player combo) while away from shore power. I realize that we probably don't need anything bigger than a 1000W inverter for the loads we're looking at, but how many batteries will I need for an average weekend anchored out? I figure the (normal)radio/cd will be playing almost all day (X2) with about 4 hours of tv time (a movie each night). I already have a deepcell 90 from west marine, but I'm curious as to how many more batteries I should plan on buying. Thanks for any input.
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Figure the Amps
If you figure the amps that each item "pulls" you can have an educated guess at the hours available or number of batteries. If the amps are not listed on the appliance, find the wattage and calculate the amps with the fomula.. P (watts)/E(voltage)=I (Amps). Most batteries will be in the 50-60 Ah (amphour) range. So if you are "pulling" 10 amps you have 5 hrs of life per battery. This is a pretty goood planning method.
If you figure the amps that each item "pulls" you can have an educated guess at the hours available or number of batteries. If the amps are not listed on the appliance, find the wattage and calculate the amps with the fomula.. P (watts)/E(voltage)=I (Amps). Most batteries will be in the 50-60 Ah (amphour) range. So if you are "pulling" 10 amps you have 5 hrs of life per battery. This is a pretty goood planning method.
Energy Budget
Mike was partly right. You don't want to pull down your batteries more than 50%. I suggest you do some research on battery charging, capacity and energy budgets. The BoatUS catalog, and the West Marine catalog and on line Advisors have lots of information. You could also get Don Casey's book about electrical systems. Calder's book is a bit of "overload" for you and your systems, although it would make a great father's day present
Mike was partly right. You don't want to pull down your batteries more than 50%. I suggest you do some research on battery charging, capacity and energy budgets. The BoatUS catalog, and the West Marine catalog and on line Advisors have lots of information. You could also get Don Casey's book about electrical systems. Calder's book is a bit of "overload" for you and your systems, although it would make a great father's day present
Thanks fellas...I think I've got it.
Ok, The TV/VCR Operates at 75W at 120V So, 75/120=0.65Amps. Using a 90Ah battery, I would get about 138 hours of usage (not counting decreasing voltage output over the corse of usage). Now, since I don't want to burn through batteries quickly. I figure I can get about 69 (138/2)hours of usage (at .65Amps) safely (without calculating voltage drain). Being VERY conservative, let's say that there's a 30% drain on a regular acic/gel marine battery. This should mean that I should be able use this TV system for about 20 hours on one (new-fully charged) 90Ah battery without abusing the battery. Correct? Again, I'm new to this, so I'm trying to see if I understand what I'm saying. Thank you
Ok, The TV/VCR Operates at 75W at 120V So, 75/120=0.65Amps. Using a 90Ah battery, I would get about 138 hours of usage (not counting decreasing voltage output over the corse of usage). Now, since I don't want to burn through batteries quickly. I figure I can get about 69 (138/2)hours of usage (at .65Amps) safely (without calculating voltage drain). Being VERY conservative, let's say that there's a 30% drain on a regular acic/gel marine battery. This should mean that I should be able use this TV system for about 20 hours on one (new-fully charged) 90Ah battery without abusing the battery. Correct? Again, I'm new to this, so I'm trying to see if I understand what I'm saying. Thank you
Not Quite
It would be 75 watts at 12 volts. And since you would have to go through an inverter to get back to 120 volts (assuming your tv is not 12 volt dc compatible) then subtract another 10% or so. Figure on about 5 hours usage given the rest of the parameters. Dan Jonas (S/V Feije II)
It would be 75 watts at 12 volts. And since you would have to go through an inverter to get back to 120 volts (assuming your tv is not 12 volt dc compatible) then subtract another 10% or so. Figure on about 5 hours usage given the rest of the parameters. Dan Jonas (S/V Feije II)
No need for rocket science ...
borrow a second battery ... then go out and see just what your one battery will do and use the second one for an emergency spare. ... some of the TV/DVDs kick out at a higher voltage than you would expect. 12.1 or 12.3 ... so you may have enough to run a couple of lights or a GPS or even start an engine ... but not enough to run the TV/DVD combo. Recently found a Sony that need the engine on and charging at 14+ to start working and then it would continue to work OK after the engine was shut down. So forget the formulas because there are too many variables ... test what you want to do and then keep adding capability to make it go. Vic
borrow a second battery ... then go out and see just what your one battery will do and use the second one for an emergency spare. ... some of the TV/DVDs kick out at a higher voltage than you would expect. 12.1 or 12.3 ... so you may have enough to run a couple of lights or a GPS or even start an engine ... but not enough to run the TV/DVD combo. Recently found a Sony that need the engine on and charging at 14+ to start working and then it would continue to work OK after the engine was shut down. So forget the formulas because there are too many variables ... test what you want to do and then keep adding capability to make it go. Vic
wrong calculations
Your calculations are assuming 120 volts. You have to translate to 12 volt which will give 13.9 hours of theoretical operation not 139. Sounds like you need another start battery of similar size for the usage you intend. Good luck
Your calculations are assuming 120 volts. You have to translate to 12 volt which will give 13.9 hours of theoretical operation not 139. Sounds like you need another start battery of similar size for the usage you intend. Good luck
Take 2, throw one
Take two batteries. Run the TV/VCR on battery one until its flat out. Tie rope to TV/VCR and throw overboard for as a second anchor (Bahamian moor). Talk to your crew, play cards by flashlight, watch the stars (did you see the lunar eclipse tonight?). Go to sleep. Your TV/VCR is now ruined, tie a marker to it for the next anchoring out!
Take two batteries. Run the TV/VCR on battery one until its flat out. Tie rope to TV/VCR and throw overboard for as a second anchor (Bahamian moor). Talk to your crew, play cards by flashlight, watch the stars (did you see the lunar eclipse tonight?). Go to sleep. Your TV/VCR is now ruined, tie a marker to it for the next anchoring out!
I agree with andy..
anyway, why would you want to go to all the trouble to take the boat out just to watch TV. Do yourself a favor.... discover the joy of reading. Save the DVD's for home or dockside....
anyway, why would you want to go to all the trouble to take the boat out just to watch TV. Do yourself a favor.... discover the joy of reading. Save the DVD's for home or dockside....
tv on board
OSU; If you want to watch a movie with your Honey at anchor, do it; it's your boat, let others do what they want to do on their boats. Opinions are like bellybuttons: everybody has one. A 13" TV/VCR draws about 4 or 5 amps when it's run through an inverter. The DVD will draw even less. For safety sake, don't depend on your house battery to start an inboard engine; have another battery you can put into the system, too. Deep cycle batteries don't make the best engine start batteries. The best bet is dedicated house and engine start batts. Enjoy.
OSU; If you want to watch a movie with your Honey at anchor, do it; it's your boat, let others do what they want to do on their boats. Opinions are like bellybuttons: everybody has one. A 13" TV/VCR draws about 4 or 5 amps when it's run through an inverter. The DVD will draw even less. For safety sake, don't depend on your house battery to start an inboard engine; have another battery you can put into the system, too. Deep cycle batteries don't make the best engine start batteries. The best bet is dedicated house and engine start batts. Enjoy.
Energy audit
I love living in America!! We are free to as we wish with our free time, how you spend yours is your choice. If you wish to participate in Mindless T.V. at anchor ,the inverter (Xantrex) manufacture has a web page for an energy audit that will help decide how much electron storage will be required.(www.xantrex.com/support/howlong.asp) By the way,Captian Ron is the only DVD you need onboard.
I love living in America!! We are free to as we wish with our free time, how you spend yours is your choice. If you wish to participate in Mindless T.V. at anchor ,the inverter (Xantrex) manufacture has a web page for an energy audit that will help decide how much electron storage will be required.(www.xantrex.com/support/howlong.asp) By the way,Captian Ron is the only DVD you need onboard.
12 volt appliances
Why not just buy a TV that runs off of 12vdc. They run off cigaette lighter plugs and D cell batteries.
Why not just buy a TV that runs off of 12vdc. They run off cigaette lighter plugs and D cell batteries.
Solar panel
I keep a 11 watt flexible solar panel hooked up to my system. It only charges at about .8 amp, but it helps keep the battery topped off, thus prolonging its life. A good 35 watt panel can be had for $300-400, are not much larger than the flexibles, but are rigid and difficult to locate on a small yacht. Best bet is have a bank big enough so you don't discharge below 50%. And don't fall asleep with the tube on!
I keep a 11 watt flexible solar panel hooked up to my system. It only charges at about .8 amp, but it helps keep the battery topped off, thus prolonging its life. A good 35 watt panel can be had for $300-400, are not much larger than the flexibles, but are rigid and difficult to locate on a small yacht. Best bet is have a bank big enough so you don't discharge below 50%. And don't fall asleep with the tube on!
Thanks for the responses
Thanks for all the replies forks. It'll definately help. For the purists out there, The wife and I didn't buy a boat so we can spend hours bobbing while watching movies, but it's nice to have that option.
Thanks for all the replies forks. It'll definately help. For the purists out there, The wife and I didn't buy a boat so we can spend hours bobbing while watching movies, but it's nice to have that option.
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