crholliday
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- Sep 21, 2020
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12v, 24v or 48v on sailboat
- Thread starter crholliday
- Start date
(John Simmons
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- Feb 1, 2020
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I looked over your spreadsheet and cannot fault your attention to detail, it truly was impressive.
Keep the boat at 12 Volts. It is not worth it to do anything else. The cost and complexity will outweigh any small gains that you might achieve.
I have met many boats, and unless they are running AC’s off the solar panel, none have EVER used 900Ah in a day. That is literally a phenomenal amount of energy usage in a sailboat. With your proposed 2000W of solar power you could run an AC during the hottest part of the day for a couple of hours. I know a catamaran here who does that.
Since you own that really nice generator —-13.5KW????—-that is going to die a faster death if you do not use it regularly, I would consider moving some things around. For instance, get a 120V AC water maker. While you are making water, charge up your batteries, and run your washing machine, make coffee, charge up your Ryobi drill Etc. A DC water maker is a great thing until you have to get the high pressure pump replaced. The DC water maker system is great if you don’t have a generator, but you do. Use it, things on a boat break faster if they are not used. An AC water maker will give you more water, be cheaper to buy and run, and it will give that Genset something to do. You can NEVER have too much water maker capacity. Get one with two 48 inch membranes NON PROPRIETARY membrane size. This is a really important thing when it comes time to cough up the bucks for new membranes. Some water maker companies have pressure vessels which will ONLY fit their super expensive proprietary membranes.
My boat is a 47’ Valiant Monohull. I use 120 Ah a day at anchor (120 AC water maker, 120 AC holding plate refrigeration), and 200Ah when sailing (autopilo, radar, AIS, GPS etc). We run the generator 6.5KW once a day in the morning for an hour or so to make water, freeze the holding plate down, heat water for warm showers, and if necessary charge the batteries. We have a washing machine, but use propane, and unfortunately no microwave. We also have DC refrigeration/ freezer that uses 11 amps and runs during the day. We normally shut it down at night because the holding plate keeps everything nice and cold and it doesn’t get opened much. Nothing is preventing us from running it all the time, but it was just a use model we fell into.
My solar system is only 500 Watts and has reliably topped up my old 800Ah AGM system almost every day. I now have a 1200Ah LiFePhO4 bank. Why I went so big is still a mystery to me, but the space was available after the old AGM’s came out so I filled it up.
I think your numbers are a bit pessimistic and with some thought, you can take a lot of your problems out of the equation just by changing how you do things.
If i was in your position, I would add all the solar you can, and then when the AGM’s die in a year or two or three and you have a better handle on how you use your boat and what your usage model is, then by all means go Lithium. For now, keep the batteries you have and make changes after you see what you really need. Simple things like turning your inverter off when it is not needed can save an eye opening amount of power. I have seen some units with 5 amps of standby current (5*24=120Ah per day). Just for this reason I added a small 200 Watt inverter that is on all the time for small loads like the computer chargers, the iPad, the iridium GO, the TV etc). The big unit gets turned on when I want to run larger items like a vacuum cleaner, or something like that.
You are going to be spending SO much money on other things that it just makes sense to leave your electric system alone for now. It is not only not broken, it is Brand new and still under warranty!
Keep the boat at 12 Volts. It is not worth it to do anything else. The cost and complexity will outweigh any small gains that you might achieve.
I have met many boats, and unless they are running AC’s off the solar panel, none have EVER used 900Ah in a day. That is literally a phenomenal amount of energy usage in a sailboat. With your proposed 2000W of solar power you could run an AC during the hottest part of the day for a couple of hours. I know a catamaran here who does that.
Since you own that really nice generator —-13.5KW????—-that is going to die a faster death if you do not use it regularly, I would consider moving some things around. For instance, get a 120V AC water maker. While you are making water, charge up your batteries, and run your washing machine, make coffee, charge up your Ryobi drill Etc. A DC water maker is a great thing until you have to get the high pressure pump replaced. The DC water maker system is great if you don’t have a generator, but you do. Use it, things on a boat break faster if they are not used. An AC water maker will give you more water, be cheaper to buy and run, and it will give that Genset something to do. You can NEVER have too much water maker capacity. Get one with two 48 inch membranes NON PROPRIETARY membrane size. This is a really important thing when it comes time to cough up the bucks for new membranes. Some water maker companies have pressure vessels which will ONLY fit their super expensive proprietary membranes.
My boat is a 47’ Valiant Monohull. I use 120 Ah a day at anchor (120 AC water maker, 120 AC holding plate refrigeration), and 200Ah when sailing (autopilo, radar, AIS, GPS etc). We run the generator 6.5KW once a day in the morning for an hour or so to make water, freeze the holding plate down, heat water for warm showers, and if necessary charge the batteries. We have a washing machine, but use propane, and unfortunately no microwave. We also have DC refrigeration/ freezer that uses 11 amps and runs during the day. We normally shut it down at night because the holding plate keeps everything nice and cold and it doesn’t get opened much. Nothing is preventing us from running it all the time, but it was just a use model we fell into.
My solar system is only 500 Watts and has reliably topped up my old 800Ah AGM system almost every day. I now have a 1200Ah LiFePhO4 bank. Why I went so big is still a mystery to me, but the space was available after the old AGM’s came out so I filled it up.
I think your numbers are a bit pessimistic and with some thought, you can take a lot of your problems out of the equation just by changing how you do things.
If i was in your position, I would add all the solar you can, and then when the AGM’s die in a year or two or three and you have a better handle on how you use your boat and what your usage model is, then by all means go Lithium. For now, keep the batteries you have and make changes after you see what you really need. Simple things like turning your inverter off when it is not needed can save an eye opening amount of power. I have seen some units with 5 amps of standby current (5*24=120Ah per day). Just for this reason I added a small 200 Watt inverter that is on all the time for small loads like the computer chargers, the iPad, the iridium GO, the TV etc). The big unit gets turned on when I want to run larger items like a vacuum cleaner, or something like that.
You are going to be spending SO much money on other things that it just makes sense to leave your electric system alone for now. It is not only not broken, it is Brand new and still under warranty!
Mango boat
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