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#1
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One more inverter question
So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I
want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen |
#2
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Hello Stephen,
Just do the math. 2300 watts is about 200 amps at 12 volts! That's maybe 3 hp with no losses, so your Yanmar can handle it, but not many alternators will handle 200 amps continuously. What your alternator doesn't supply will come from the batteries. They'll discharge fairly quickly. Forget the electric heater. A microwave might be practical for short periods, and a power tool like an electric drill should be no problem at all. A boombox may be a small load, but a TV/VCR may not be. For a load of 120 watts, you're talking about a dc current of more than 10 amperes. Depending on the state of charge and capacity of your batteries, you could get a couple of hours of TV from them. Good luck. Chuck Stephen Trapani wrote: So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen |
#3
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Comments below:
"Stephen Trapani" wrote in message news So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen Simple math. Watts = Amps x Volts So, lets say the alternator attached to your Yanmar is capable of putting out a sustained 65 amps at 14.6 volts with the engine running at, say, 2000 RPM without overheating or burning up the belt or whatever. And it can do this for as long as you want to support a heavy load on your inverter. So: 14.6 volts x 65 amps = 949 watts x 85 % efficiency = 800 watts or so. This means, if your inverter is 85 % efficient at converting 14.6 volts to 115 volts you will only be able to get enough power from your alternator through to your inverter to deliver a sustained 800 watts to whatever it is you want to run. In other words, if you run a 1000 watt electric heater (and most are 1500 watts or more) off your inverter with your engine running you will still be slowly running your batteries down. Any sustained load below 800 watts or so will run off the alternator, with perhaps a little left to trickle charge the batteries. On the other hand, if your load is intermittent, like a power tool, or microwave, it depends on how much of the time the tool/whatever is running. If it causes the inverter to draw more than your charging system can deliver it will draw the extra from the batteries but when the tool is off the alternator will charge the batteries back up. Expect more inefficiency in charging the batteries so it wont be a 1 to 1 relationship of run time to recovery time, more like 1 to 2 or worse. But it can be done and is. You should probably forget about the heater though... Make sense? -- Ken Heaton, Cape Breton Island, Canada kenheaton AT ess wye dee DOT eastlink DOT ca |
#4
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Ken Heaton wrote:
Comments below: "Stephen Trapani" wrote in message news So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen Simple math. Watts = Amps x Volts So, lets say the alternator attached to your Yanmar is capable of putting out a sustained 65 amps at 14.6 volts with the engine running at, say, Okay, so my amp meter reads somewhere around 45 amps when it is charging the battery, so I figure 45? X 14.6v? so I can expect, say 80% efficiency just to be safe, 525 watts? 2000 RPM without overheating or burning up the belt or whatever. And it can do this for as long as you want to support a heavy load on your inverter. So: 14.6 volts x 65 amps = 949 watts x 85 % efficiency = 800 watts or so. This means, if your inverter is 85 % efficient at converting 14.6 volts to 115 volts you will only be able to get enough power from your alternator through to your inverter to deliver a sustained 800 watts to whatever it is you want to run. In other words, if you run a 1000 watt electric heater (and most are 1500 watts or more) off your inverter with your engine running you will still be slowly running your batteries down. Any sustained load below 800 watts or so will run off the alternator, with perhaps a little left to trickle charge the batteries. I can tell by the amp hour rating of the batteries how long the two group 27s will hold up in this over-use state, right? How do you figure that? It will suck anything over 45 off the the batteries draining the batteries faster the higher the charge? 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? Will the 12 volt Bible cover this? I just ordered it. On the other hand, if your load is intermittent, like a power tool, or microwave, it depends on how much of the time the tool/whatever is running. If it causes the inverter to draw more than your charging system can deliver it will draw the extra from the batteries but when the tool is off the alternator will charge the batteries back up. Expect more inefficiency in charging the batteries so it wont be a 1 to 1 relationship of run time to recovery time, more like 1 to 2 or worse. But it can be done and is. You should probably forget about the heater though... One more question, is this sort of usage hard on the batteries at all? Wear them out faster or anything? Make sense? Very helpful, thank you! Stephen |
#5
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YES! That type of discharge cycle is VERY hard on batteries. Most Type
27 deep cycle batteries are good for about 280-360 discharge/charge cycles. You didn't indicate if your type 27s were deep cycle. If they are standard auto starting batteries, the cycles will be less. You should never discharge the batteries below 50% capacity. If you want to run a 2300 watt inverter, get a pair of Trojan J305HC batteries (335 Amp Hrs). a Balmar 100 Amp alternator, a three stage regulator for the alternator,a Balmar Duo-charge, and keep the 27 for a starting battery. krj Stephen Trapani wrote: Ken Heaton wrote: Comments below: "Stephen Trapani" wrote in message news So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen Simple math. Watts = Amps x Volts So, lets say the alternator attached to your Yanmar is capable of putting out a sustained 65 amps at 14.6 volts with the engine running at, say, Okay, so my amp meter reads somewhere around 45 amps when it is charging the battery, so I figure 45? X 14.6v? so I can expect, say 80% efficiency just to be safe, 525 watts? 2000 RPM without overheating or burning up the belt or whatever. And it can do this for as long as you want to support a heavy load on your inverter. So: 14.6 volts x 65 amps = 949 watts x 85 % efficiency = 800 watts or so. This means, if your inverter is 85 % efficient at converting 14.6 volts to 115 volts you will only be able to get enough power from your alternator through to your inverter to deliver a sustained 800 watts to whatever it is you want to run. In other words, if you run a 1000 watt electric heater (and most are 1500 watts or more) off your inverter with your engine running you will still be slowly running your batteries down. Any sustained load below 800 watts or so will run off the alternator, with perhaps a little left to trickle charge the batteries. I can tell by the amp hour rating of the batteries how long the two group 27s will hold up in this over-use state, right? How do you figure that? It will suck anything over 45 off the the batteries draining the batteries faster the higher the charge? 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? Will the 12 volt Bible cover this? I just ordered it. On the other hand, if your load is intermittent, like a power tool, or microwave, it depends on how much of the time the tool/whatever is running. If it causes the inverter to draw more than your charging system can deliver it will draw the extra from the batteries but when the tool is off the alternator will charge the batteries back up. Expect more inefficiency in charging the batteries so it wont be a 1 to 1 relationship of run time to recovery time, more like 1 to 2 or worse. But it can be done and is. You should probably forget about the heater though... One more question, is this sort of usage hard on the batteries at all? Wear them out faster or anything? Make sense? Very helpful, thank you! Stephen |
#6
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On Sat, 26 Mar 2005 10:40:18 -0800, Stephen Trapani
wrote: So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen If I recall correctly, the stock (Hitachi?) alternator on my 2GM was only rated at 35 amps - that would only be enough to sustain a 3 amp (360 watt) load at 120 volts. (I replaced the stock alternator with a higher output unit, and a smart regulator, to give me some chance of keeping the batteries charged.) Given the small alternator, and your very small battery bank, I think the 2300 watt inverter is excessively large. In any case, I would strongly recommend doing some re-wiring so that you have a dedicated starting battery, and the inverter, and other non-engine loads, will run off separate deep cycle batteries. Forget about electric heat - it just isn't feasible with the batteries you have. 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! -- 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 |
#7
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Peter Bennett wrote:
On Sat, 26 Mar 2005 10:40:18 -0800, Stephen Trapani wrote: So, say I've got a measley 2 group 27s and my old Yanmar 2GM15 and I want to by a 2300watt continuous inverter. BUT... I'm willing to run the Yanmar while I'm using any heavy loads like a power tool, microwave, or electric heat and I only use the inverter *without* running the Yanmar/alternator for small loads like a TV/VCR or a boombox. Any problem with that? Stephen If I recall correctly, the stock (Hitachi?) alternator on my 2GM was only rated at 35 amps - that would only be enough to sustain a 3 amp (360 watt) load at 120 volts. (I replaced the stock alternator with a higher output unit, and a smart regulator, to give me some chance of keeping the batteries charged.) Given the small alternator, and your very small battery bank, I think the 2300 watt inverter is excessively large. In any case, I would strongly recommend doing some re-wiring so that you have a dedicated starting battery, and the inverter, and other non-engine loads, will run off separate deep cycle batteries. Yeah, that would be cool. I've got a '79 Hunter 33.' Maybe I've got a mental block but I can't figure out where I could possibly put another battery bank. It's got little enough storage as it is. Seems I'd have to use the, um lockers under the, um port and starboard settees. Yuck. I wish I had more clearance above bilge pump in the bilge! The whole dang bilge is only about 18 inches deep or so. So that's why I've been asking about the cheaper, easier, but less powerful solution with the 2 group 27s I know I can fit. 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. 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 |
#8
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Stephen Trapani wrote:
Peter Bennett wrote: 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? Only if you never go outside the range of SeaTow. If you have a number of electrical loads, its only a matter of time before you wake up and find the anchor light, plus the TV that you forgot to turn off, has drained the batteries. So the question becomes, do you need to start the engine to get back home? I would think that there is some place you could find to stash a small AGM starting battery that would greatly reduce this risk. BTW, one of my "pet peeves" is using an inverter to power a small TV, when there are plenty of TVs that run on DC more efficiently. You should read the specs carefully, because many TVs have significant loads, even when "turned off." For instance, my AC/DC 9 inch Panasonic draw almost 2 Amps more when powered on AC, and that load continues simply by being plugged in. This means that you could inadvertently draw an extra 25 Amp-hours overnight from this alone. There are other "forgotten" loads to think about. If you run the propane through a shutoff solenoid, that may draw a half Amp. And if you run it all night for a heater, you should have leak detector - another small but constant load. |
#9
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#10
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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. |
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