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On Sat, 26 Mar 2005 20:48:42 -0800, Stephen Trapani
wrote: Peter Bennett wrote: Forget about electric heat - it just isn't feasible with the batteries you have. Yeah, I've got a Force 10 propane. I'll get that working soon, hopefully. I just thought maybe I could use the floor electric heater in a backup situation if I needed to, on the 850watt setting if I need to. Looks like it won't be good for much else. If I recall correctly, Group 27 deep cycle batteries are rated at 100 - 110 Ampere-hours, so you have about 200 AH capacity in total. It is generally recommended that deep cycle batteries should not be discharged more than half-way, so your usable capacity it only 100 AH. Your 850 watt heater will draw about 7 amps at 120 V, and the inverter will draw perhaps 75 - 80 amps (allowing for inverter inefficiencies). The AH rating of a battery is calculated assuming the battery will be fully discharged in 20 hours - for your 200 AH battery bank, this would mean a 10 amp discharge current. If you discharge the battery at greater than the 20 hour rate, the total energy you can extract is reduced. Your heater would require about 8 times the 20 hour rate. The table I have for this only goes up to 5, where the effective capacity is reduced to 72%. You could probably expect about 60% capacity, so you could only run the heater for about 40 minutes. (and then you might have trouble starting the engine.) The microwave, power tools (and possibly an electric kettle) are OK, as they are short-term loads, and the total ampere-hours used by them should be fairly low. The TV and boom box would be on for longer periods, but are fairly low draw, so may also be OK - but I would definitely want a separate starting battery! So in order to do without the seperate starting battery I can manage with careful planning, etc? Stephen Yes, maybe... You should look at the current required for each device you want to use, and how long you will use it, to determine the ampere-hours you will consume between recharges. A battery monitor like the Xantrex Link 20 can help you monitor the state of charge of your batteries. I still strongly recommend adding a separate starting battery - it is valuable insurance in the event you do discharge the house batteries too far. You should also replace the stock voltage regulator on the alternator with a "smart" or three-stage type - this will allow the engine to recharge the batteries much more effectively than it does now. A three-stage AC charger would also be a good investment (there may be one built into the inverter...) -- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca |
Comments inserted where appropriate below:
"Peter Bennett" wrote in message news.com... On Sat, 26 Mar 2005 20:48:42 -0800, Stephen Trapani wrote: Peter Bennett wrote: Forget about electric heat - it just isn't feasible with the batteries you have. Yeah, I've got a Force 10 propane. I'll get that working soon, hopefully. I just thought maybe I could use the floor electric heater in a backup situation if I needed to, on the 850watt setting if I need to. Looks like it won't be good for much else. If I recall correctly, Group 27 deep cycle batteries are rated at 100 - 110 Ampere-hours, so you have about 200 AH capacity in total. It is generally recommended that deep cycle batteries should not be discharged more than half-way, so your usable capacity it only 100 AH. Your 850 watt heater will draw about 7 amps at 120 V, and the inverter will draw perhaps 75 - 80 amps (allowing for inverter inefficiencies). The AH rating of a battery is calculated assuming the battery will be fully discharged in 20 hours - for your 200 AH battery bank, this would mean a 10 amp discharge current. If you discharge the battery at greater than the 20 hour rate, the total energy you can extract is reduced. Your heater would require about 8 times the 20 hour rate. The table I have for this only goes up to 5, where the effective capacity is reduced to 72%. You could probably expect about 60% capacity, so you could only run the heater for about 40 minutes. (and then you might have trouble starting the engine.) I'd go a little further on this estimate. Yes, you shouldn't go below 50% charge on your batteries which reduces your 200 AH battery bank to an effective 100 AH total as stated above, but you also will find it difficult to get your battery bank charged much above 85% by running the engine. An AC charger plugged into shore power running overnight is about the olny way you'll do it. It takes too long to trickle those last few amp hours in. So you've really only 70 AH total to work with in your two group 27's. I'd forget about the electric heater unless you can stay below 400 watts with the engine running. The rest of the things you suggested running off the inverter should be OK due to their intermittant use as explained by others. You asked a couple of questions in another post: "And then if I keep running the over-use after the batteries run down, the inverter overharge alarm will go on? No big deal I can just turn off the large draw and charge up the batteries before I turn off the Yanmar?" and: "One more question, is this sort of usage hard on the batteries at all? Wear them out faster or anything?" Running the inverter until the low battery voltage alarm comes on will take your batteries to a charge level far below 50% which will shorten their life quite dramatically, perhaps ruining them in just a few of these very deep cycles. The microwave, power tools (and possibly an electric kettle) are OK, as they are short-term loads, and the total ampere-hours used by them should be fairly low. The TV and boom box would be on for longer periods, but are fairly low draw, so may also be OK - but I would definitely want a separate starting battery! A separate starting battery wouldn't have to be very big, perhaps one the size used in a lawn tractor would do? It shouldn't be hard to find a place to put one that small. So in order to do without the seperate starting battery I can manage with careful planning, etc? Stephen Yes, maybe... You should look at the current required for each device you want to use, and how long you will use it, to determine the ampere-hours you will consume between recharges. A battery monitor like the Xantrex Link 20 can help you monitor the state of charge of your batteries. I still strongly recommend adding a separate starting battery - it is valuable insurance in the event you do discharge the house batteries too far. You should also replace the stock voltage regulator on the alternator with a "smart" or three-stage type - this will allow the engine to recharge the batteries much more effectively than it does now. A three-stage AC charger would also be a good investment (there may be one built into the inverter...) -- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca |
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"Ken Heaton" wrote in
news:RZE1e.114238$fc4.16211@edtnps89: I'd forget about the electric heater unless you can stay below 400 watts Can I ask a silly question? Geez, don't tell any of the yacht professionals hanging around the dock if you do this, but why can't we simply install an ENGINE POWERED HEATER like the beast that turns my stepvan into an oven into the boat's cooling water loop, like the water heater??......Silly me. http://www.rustrepair.com/stepvan_pa...v&p=wi-heater- ht.aux The 6x7x6" 13,000 BTU small unit puts out TWICE as much heat as a 1500 watt AC heater many of you have now. Just mount it up under a table near the engine compartment to keep the hoses short and you're in business. Bigger boat? I have the 20,000 BTU unit in the back of my stepvan and at 30F it will run you out in 10 minutes! They have a 33,000 BTU model if you need it. They are very small....no bigger than your little electric heater you keep tripping over in the passageway. You'll need a heater control valve to control the water flow.... http://www.rustrepair.com/stepvan_pa...v&p=wi-heater- ht.val To be really nice, get one that uses a cable control.... 54-062 62" cable with knob that mounts through a simple hole. And a fan speed control.... http://www.rustrepair.com/stepvan_pa...sv&p=wi-heater switch and resistor.... These units are all made to run from the helm of the stepvan with the heater in the back so controls are separate. Sure beats the hell out of running the engine and inverter to power that crappy little heater in the passageway..... |
I know of a number of boat that have a similar setup. Webasto sells a whole
like of hot water based cabin heaters. So does Espar. I have seen several boats that have used regular automotive heater cores. No problem other than having to run the engine to get heat. Doug "Larry W4CSC" wrote in message ... "Ken Heaton" wrote in news:RZE1e.114238$fc4.16211@edtnps89: I'd forget about the electric heater unless you can stay below 400 watts Can I ask a silly question? Geez, don't tell any of the yacht professionals hanging around the dock if you do this, but why can't we simply install an ENGINE POWERED HEATER like the beast that turns my stepvan into an oven into the boat's cooling water loop, like the water heater??......Silly me. http://www.rustrepair.com/stepvan_pa...v&p=wi-heater- ht.aux The 6x7x6" 13,000 BTU small unit puts out TWICE as much heat as a 1500 watt AC heater many of you have now. Just mount it up under a table near the engine compartment to keep the hoses short and you're in business. Bigger boat? I have the 20,000 BTU unit in the back of my stepvan and at 30F it will run you out in 10 minutes! They have a 33,000 BTU model if you need it. They are very small....no bigger than your little electric heater you keep tripping over in the passageway. You'll need a heater control valve to control the water flow.... http://www.rustrepair.com/stepvan_pa...v&p=wi-heater- ht.val To be really nice, get one that uses a cable control.... 54-062 62" cable with knob that mounts through a simple hole. And a fan speed control.... http://www.rustrepair.com/stepvan_pa...sv&p=wi-heater switch and resistor.... These units are all made to run from the helm of the stepvan with the heater in the back so controls are separate. Sure beats the hell out of running the engine and inverter to power that crappy little heater in the passageway..... |
On Sun, 27 Mar 2005 19:49:53 -0500, Larry W4CSC
wrote: Can I ask a silly question? Geez, don't tell any of the yacht professionals hanging around the dock if you do this, but why can't we simply install an ENGINE POWERED HEATER like the beast that turns my stepvan into an oven into the boat's cooling water loop, like the water heater??......Silly me. That's a good suggestion in some situations - but the 2GM15 is a two cylinder 15 HP engine commonly used on sailboats around 30 ft, and is probably raw-water cooled, so your suggestion won't work. Even if the engine has a fresh water cooling system, an engine-powered heater like you suggest will only be useful while the engine is running - unless the OP wants to leave his engine running all evening while at anchor, it won't help. I think the best solution for his heating problem is a small Espar or Webasto diesel hot air furnace. He did mention that he has a Force 10 propane heater. The one I had one on a previous boat was a bulkhead-mounted "fireplace" with no provision to circulate the air. When I stood up in the boat, my head was cooking, but my feet were freezing.... That sort of heater needs a fan mounted above it to circulate the heated air. -- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca |
Just read the voltage coming out of the power supply dongle on the
LCD TV you're considering and look for anything from 12-15VDC output from it. The DC regulators are inside the TVs so it doesn't matter if it's off a few volts. Bad advice concerning the consumer grade LCD TVs I know of. The 120 volt AC to 12 volt wall wart *is* the voltage regulator, there is no DC regulator inside the TV. I called technical support concerning my Samsung SyncMaster 150mp and they said the voltage must be a clean 12.3 volts plus or minus 5%. Clean means no high voltage spikes or significant AC ripple. They said lots of folks are running this particular monitor in emergency vehiclesetc., but only by using a 10-16v--12v regulated power supply (expensive), *not* connecting directly to the vehicle's DC bus. Typical boat voltages range from 10v or so when running heavy loads like anchor windlasses, to 14.4v or so when charging. High voltages will burn out the cold cathode fluorescent backlight circuitry, every time. You either have an unusual LCD TV, never use the TV during the top end of a 3-step charging cycle, or are just plain lucky. |
"Mark" wrote in
ups.com: You either have an unusual LCD TV, never use the TV during the top end of a 3-step charging cycle, or are just plain lucky. I'll get the make/model next time I'm on the boat and post it. Functions flawlessly, here. |
Peter Bennett wrote in
news.com: I think the best solution for his heating problem is a small Espar or Webasto diesel hot air furnace. He did mention that he has a Force 10 propane heater. The one I had one on a previous boat was a bulkhead-mounted "fireplace" with no provision to circulate the air. When I stood up in the boat, my head was cooking, but my feet were freezing.... That sort of heater needs a fan mounted above it to circulate the heated air. This is the best idea, but there's no room on the small cruisers for it. Lionheart had a fuel oil forced air heater installed in the port lazarette when it was built. By the time Geoffrey got it, the heater was all rotten inside and he removed it to make room for the aft cabin heat pump, which is more important in Charleston. It looked like the salt air had simply consumed the diesel heater's steel combustion chamber. It was totally rusted out. |
In article .com,
Peter Bennett wrote: That's a good suggestion in some situations - but the 2GM15 is a two cylinder 15 HP engine commonly used on sailboats around 30 ft, and is probably raw-water cooled, so your suggestion won't work. Why would the fact that you have Raw water cooling be a deterent? All that is required is some High Temp Hose, and a Stainless Liquid/Air Heat Exchanger. Install the heat exchanger between the output of the engine block and the input to the Raw Water Exhaust Elbow Input. If you want heat just turn of the fan blowing thru the heat exchanger. If you don't want heat, just let the Raw water flow overboard after going thru the heat echanger. This isn't Rocket Scienc. Cogeneration of this type has been used on many a small vessel for many, many years, Fresh water or Raw water cooled. Look, you already PAID for those BTU's when you purchased your Dead Dinasour Guts. Better to use them, then heat up the ocean with them. Remeber 33% of your BTU's go out the output shaft, 33% go out the cooling system, and 33% go up the stack, in diesel engines. Bruce in alaska who would like to sell you some more dinasour guts... -- add a 2 before @ |
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