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Old 08-15-2016, 05:55 AM   #61
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Originally Posted by Simi 60 View Post
Pretty disgusted at what I see as inefficiency in gensets.
I have a 7kva genset which according to online calculators churns out 290 amps at 24v.
I have a 5000va inverter/120amp charger so it wont take all the amps.

What are you supposed to do with the extra juice?

Run the water heater and ACs, anything else you've got that won't go (or doesn't need to be) on the inverter??

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Old 08-15-2016, 06:30 AM   #62
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Quote:
Pretty disgusted at what I see as inefficiency in gensets.
I have a 7kva genset which according to online calculators churns out 290 amps at 24v.
I have a 5000va inverter/120amp charger so it wont take all the amps.
Better read up or talk to a tech about how a generator an electricity works. It doesn't put out any "extra juice". At lower loads it consumes less fuel. let us know when you recover the cost of the solar once you understand how much fuel you are actually using.
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Old 08-15-2016, 09:04 AM   #63
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I also have a Californian 34, with 2 8D House/Starting Batteries and a Nova Kool fridge.

If I am off the dock for several days, I am unable to maintain 100 charge with the original 20 amp charger and the generator running 2 hours a day.

The generator has lots of reserve capacity - I am thinking of going to a 40 amp charger. Any suggestions on the size of charger I should install?

jimk
Chances are good that your 20 amp charger is as old as the boat, therefore, not "smart", likely ferroresonant, so generates enough heat to keep the engine room warm all winter. To put back the amp hours you use in a day, 2 hrs of gen time will only get you about 20 amp hours, as the nominal rating is only available for a short while as you start generating, and drops quickly.
A three stage regulator will help a lot, and comes in a modern charger. With a "smart" regulator on a 100 amp charger, 2 hrs of gen time will get you closer to 160 amp hours, so might keep up to your daily usage. If you get one with an inverter built in, watch out for the extra 5+ amps the inverter will take, even at no load. Some are better than others, I know mine uses over 5 amps unloaded, so I keep it off unless I am prepared to pay that rate.
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Old 08-15-2016, 09:29 AM   #64
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"If I am off the dock for several days, I am unable to maintain 100 charge with the original 20 amp charger and the generator running 2 hours a day."

Even with a 200A charger you will not maintain the batts at 100% full in 2 hours a day.

LA batts are charged at about 15% max of their 20 hour rating, and the charge will taper at about 85% full to keep the batts from overheating.

Your SCO meter is your friend , if you can operate 50% then charge to 85% there will be some long term loss of bat capacity.

One solution is a solar panel to add that 15% daily.Best!

Second is to oversize the house bank so operating 50% up to 85% gives enough juice for your daily requirements.
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Old 08-15-2016, 10:03 AM   #65
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I spend all spring and fall on the boat 6 months a year. We are in the caribbean so run the genny all night for the aircon, it also charges the battery bank 10x T105+'s plus runs all 110vac Fridges(2) etc. Normally shut of by 7a.m. and then I have 1 kw of solar panels on the flybridge roof, that runs the boat all day. Most daytime cooking is 110vdc small rings, only turn the big 220v cooker and generator on when large meals and guests are on board. The inverter (2.8kw) and battery bank handles the 110vac during daytime comfortably.
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Old 08-15-2016, 10:40 AM   #66
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let us know when you recover the cost of the solar once you understand how much fuel you are actually using.
As a live-aboard I dont think it will take long to recover the cost of the solar, not when buying Tier 1 250 watt panels at $140 each.
Genset is not just fuel, there is also oil, filters, belts, service charges and noise.
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Old 08-15-2016, 10:42 AM   #67
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LA batts are charged at about 15% max of their 20 hour rating, and the charge will taper at about 85% full to keep the batts from overheating.

Your SCO meter is your friend , if you can operate 50% then charge to 85% there will be some long term loss of bat capacity.

One solution is a solar panel to add that 15% daily.Best!

Second is to oversize the house bank so operating 50% up to 85% gives enough juice for your daily requirements.

As a former sailor, I have an inbred aversion to running a genset. I am getting over it however.

On our recent trip, the longest we went without plugging into shore power was 7 days. The boat has its original 3 x 8D sealed LA batteries for the house bank. We have 5 folks on the boat in very warm weather. No aircon. The 9' NovaKool was working overtime as well as the 12v 2' freezer we have in the cockpit. The inverter was running the sound system (silly, large 120v system big enough for a large home that the PO installed) as well as charging all the phones and tablets. Another draw is my wife's CPAP which would run off the inverter for about 8 hours each night. Then the Kuerig and microwave used the inverter some more.

During that week we didn't run the engine much more than a couple hours a day to get from one location to another. I have the inverter set to cut out if the SOC drops below 70%. I found that I would typically run the genset in the morning and evening for a couple hours each. This would usually get the SOC to 85-90%. Overnight, with the fridge, freezer, CPAP, and anchor light running, not to mention all the kids charging their phones, I could usually make about 3 cups of coffee on the Kuerig the next morning before hitting the 70% SOC cutoff. When running the genset I would also run the electric hot water heater, more for adding load to the genset than the real need for hot water.

I can't stay away from the dock for that long often unfortunately since I am still working, but some added solar would have been really nice. With the unusually nice weather, I think it wouldn't have taken much for it to get the batteries close to 100% SOC by the end of the day. Not that I minded running the genset in the evening since it really is quiet, but it would have helped to get the batteries fully charged daily.
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Old 08-15-2016, 07:44 PM   #68
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Good discussion. So do I read correctly that some of you heat water for an hour or two in the morning and have hot water for the rest of the day?
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Old 08-15-2016, 08:01 PM   #69
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As a former sailor, I have an inbred aversion to running a genset. I am getting over it however.

On our recent trip, the longest we went without plugging into shore power was 7 days. The boat has its original 3 x 8D sealed LA batteries for the house bank. We have 5 folks on the boat in very warm weather. No aircon. The 9' NovaKool was working overtime as well as the 12v 2' freezer we have in the cockpit. The inverter was running the sound system (silly, large 120v system big enough for a large home that the PO installed) as well as charging all the phones and tablets. Another draw is my wife's CPAP which would run off the inverter for about 8 hours each night. Then the Kuerig and microwave used the inverter some more.

During that week we didn't run the engine much more than a couple hours a day to get from one location to another. I have the inverter set to cut out if the SOC drops below 70%. I found that I would typically run the genset in the morning and evening for a couple hours each. This would usually get the SOC to 85-90%. Overnight, with the fridge, freezer, CPAP, and anchor light running, not to mention all the kids charging their phones, I could usually make about 3 cups of coffee on the Kuerig the next morning before hitting the 70% SOC cutoff. When running the genset I would also run the electric hot water heater, more for adding load to the genset than the real need for hot water.

I can't stay away from the dock for that long often unfortunately since I am still working, but some added solar would have been really nice. With the unusually nice weather, I think it wouldn't have taken much for it to get the batteries close to 100% SOC by the end of the day. Not that I minded running the genset in the evening since it really is quiet, but it would have helped to get the batteries fully charged daily.

That's where we were at last year. 1-2 hrs genny time twice a day. Got the batteries to 90%. This year with 435 watts of solar we ran the genny 4 times over 2 months. We just don't worry about getting the batteries to 100% SOC anymore. We get there several time a week at least.


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Old 08-15-2016, 08:29 PM   #70
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Good discussion. So do I read correctly that some of you heat water for an hour or two in the morning and have hot water for the rest of the day?
Yup. We get hot water from both the engine as well as the electric water heater. Even if we haven't run the engine on that day, running the genset for a couple hours in the morning then another couple of hours in the evening kept us well supplied with hot water for daily showers for 5 adults.

Now, the water thermostat is set too high in my opinion. It can get dangerously hot. OTOH, my wife likes to wash dishes in very hot water and the water in the hot water tank was always hot enough for showers...
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Old 08-15-2016, 08:59 PM   #71
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Yup. We get hot water from both the engine as well as the electric water heater. Even if we haven't run the engine on that day, running the genset for a couple hours in the morning then another couple of hours in the evening kept us well supplied with hot water for daily showers for 5 adults.

Now, the water thermostat is set too high in my opinion. It can get dangerously hot. OTOH, my wife likes to wash dishes in very hot water and the water in the hot water tank was always hot enough for showers...
Its the engine taking the water heater over 140F
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Old 08-15-2016, 09:12 PM   #72
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Factoring out air conditioning, generator time on the hook tends to be an hour in the morning and the evening. If I motor during the day, the 225 amp alternator 95% recharges the house bank in a few hours. If I sit the next day, I'll run the generator in the evening. Have a 20 gallon hot water tank that heats off the engine and electric. With 3 people on the boat, I will have to turn on the electric the 3rd day. Looked hard at solar and just couldn't justify the money to reduce the generator time as I seldom sit more than a couple of days in the same anchorage. If I was going to change anything in hind site on my refit, it would have been to increase the battery bank from 1,000 amps to between 1,500 and 2,000. Would like to have been able to run the stateroom air conditioning off the inverter at night. Life is too short to sleep in your own sweat.

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Old 08-16-2016, 01:04 AM   #73
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Its the engine taking the water heater over 140F

It is really hot even if we are simply at the dock plugged into shore power and haven't run the engine.
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Old 08-16-2016, 05:22 AM   #74
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dhays: 70% SOC is a little high IMO, if they are decent deep cycles you can dial that down to 50-55. Are you determining the SOC cutoff by the voltage? Measured with loads on, that too will be a too conservative reading.
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Old 08-16-2016, 05:34 AM   #75
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It is really hot even if we are simply at the dock plugged into shore power and haven't run the engine.
There is a thermostat you can adjust on the water heater for the electric temperature.

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Old 08-16-2016, 06:11 AM   #76
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Good discussion. So do I read correctly that some of you heat water for an hour or two in the morning and have hot water for the rest of the day?

That's the way ours works.

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Old 08-16-2016, 07:00 AM   #77
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Good discussion. So do I read correctly that some of you heat water for an hour or two in the morning and have hot water for the rest of the day?
Yes, same here. Our last boat had a 6 gallon water heater and it only took a half-hour. With the 12 G heater we have now it takes about an hour.

This year I added a thermostatic valve on the hot water line which prevents the water from getting too hot. I'd still prefer the hotter water for washing dishes, but it does last longer this way.
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Old 08-16-2016, 08:00 AM   #78
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Our Isotherm unit has a mixing valve so we can keep very hot water in the tank but it is cooled before it gets to the faucet. 6 gallon unit the hot water lasts all day. But we don't use hot water for washing clothes. Being the Caribbean the temperature of the cold water in our tanks is generally in the 70s and thus is the home equivalent of a warm water wash.
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Old 08-16-2016, 09:16 PM   #79
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Great stuff. Thanks folks.
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Old 08-17-2016, 05:05 AM   #80
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For anyone concerned about using "all" of the electrical output from his or her generator while it is running here is what I have done on Bay Pelican.

The water heater, AC feed on the refrigerator and freezer, the two battery chargers / inverters and two specific duplex outlets are wired so they only have power from the generator or shore power.

Thus when the generator is turned on (40 minutes in the morning) the water is heated, the refrigeration is switched over, the batteries are charged up, and the two duplex outlets are live. Attached to the two duplex outlets are all of our battery operated devices, cell phones, computers, handheld vhf radios, batteries for the power drill, hand held flood light etc. Admittedly we sometime forget to plug in certain devices. With an 8kw generator we seem to use a good portion of the output. What is nice is that the devices we don't use daily such as the drill and the flood light stay charged.
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