I am starting a little developmental project to put together a solar powered dehumidifier for my boat and would like some thoughts/input from the solar geeks on this board (and there are quite a few here!) . Here are the parameters of this project:
My boat is quite small, just a cuddy cabin for sleeping. It has about 100 cu ft. of volume. I want to keep the mildew under control in the winter while it is at our slip. That is pretty easy as the slip has power. Just plug in a dehumidifier and run the condensate down the sink.
I just bought an incredibly cheap ($20) Peltier effect dehumidifier, see- https://www.amazon.com/gp/product/B07J9JV3V5/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1. FWIW it is also incredibly well made with an electronic humidistat. It extracts a pint a day (not much but I shouldn't need much) and draws 2.8 amps at 13 V DC from an AC converter/brick.
Why Peltier? Well it draws 2.8 amps DC or about 35 watts and other compressor dehumidifiers I could find specs on were all AC and draw a couple of 100 watts or so.
I am a little disappointed at the current draw. I saw other Peltier dehumidifiers that extract 5 times more water at only a little more current. But at $20 who cares. But if this one doesn't cut it I could buy a larger one for about $60.
I hooked it up in the living room with about 60% ambient relative humidity and after ten minutes it was putting out 40% dehumidified air. The air flow was small, guessing much less than 10 cu ft cfm, but if the air leakage is small into my cuddy cabin it should keep up. I will report tomorrow what I see after 24 hours inside the boat.
But 6 months out of the year I keep the boat at a storage yard on its trailer. I am not around to monitor it and there is no AC power available at the yard. So I am thinking solar.
Peltier is simple. No moving parts and I suspect it is somewhat voltage tolerant. Probably works at 10-15 volts. The little fan motor is probably more voltage sensitive than the Peltier module but hopefully will run ok within that range.
So what I plan to do is hook it up to a 100 watt panel through a cheap PWM controller. I will try to find a controller that only starts putting out power when the voltage rises to 10V or so and limits it to less than 15V (acceptance cutoff). I think they are common.
The unit draws 2.8 amps and the 100 watt solar panel should be able to supply that for about 6 hours each day. I don't plan to use a battery but more about that as follows:
I have used sophisticated mppt controllers such as Blue Seas in boat solar systems but they had a problem with this scheme- they wouldn't work without a battery as the internal electronics were powered by the battery input/output terminals and wouldn't start working until the battery terminal voltage got up to about 10V.
Is this true in general? Not sure how to find out as I don't think that the Blue Sea manual ever said much about this. And I don't want to spend a bunch on my system. I will have $20 invested in the dehumidifier, $80 for the 100W panel and would like to use a cheap Renogy controller or similar.
And finally is there any battery (cheap of course) that can stand discharging every night to about 10 volts where the controller cuts off and back up again in the middle of the day.
More to come tomorrow when I report how the little dehumidifier dealt with the humidity on my boat.
David
My boat is quite small, just a cuddy cabin for sleeping. It has about 100 cu ft. of volume. I want to keep the mildew under control in the winter while it is at our slip. That is pretty easy as the slip has power. Just plug in a dehumidifier and run the condensate down the sink.
I just bought an incredibly cheap ($20) Peltier effect dehumidifier, see- https://www.amazon.com/gp/product/B07J9JV3V5/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1. FWIW it is also incredibly well made with an electronic humidistat. It extracts a pint a day (not much but I shouldn't need much) and draws 2.8 amps at 13 V DC from an AC converter/brick.
Why Peltier? Well it draws 2.8 amps DC or about 35 watts and other compressor dehumidifiers I could find specs on were all AC and draw a couple of 100 watts or so.
I am a little disappointed at the current draw. I saw other Peltier dehumidifiers that extract 5 times more water at only a little more current. But at $20 who cares. But if this one doesn't cut it I could buy a larger one for about $60.
I hooked it up in the living room with about 60% ambient relative humidity and after ten minutes it was putting out 40% dehumidified air. The air flow was small, guessing much less than 10 cu ft cfm, but if the air leakage is small into my cuddy cabin it should keep up. I will report tomorrow what I see after 24 hours inside the boat.
But 6 months out of the year I keep the boat at a storage yard on its trailer. I am not around to monitor it and there is no AC power available at the yard. So I am thinking solar.
Peltier is simple. No moving parts and I suspect it is somewhat voltage tolerant. Probably works at 10-15 volts. The little fan motor is probably more voltage sensitive than the Peltier module but hopefully will run ok within that range.
So what I plan to do is hook it up to a 100 watt panel through a cheap PWM controller. I will try to find a controller that only starts putting out power when the voltage rises to 10V or so and limits it to less than 15V (acceptance cutoff). I think they are common.
The unit draws 2.8 amps and the 100 watt solar panel should be able to supply that for about 6 hours each day. I don't plan to use a battery but more about that as follows:
I have used sophisticated mppt controllers such as Blue Seas in boat solar systems but they had a problem with this scheme- they wouldn't work without a battery as the internal electronics were powered by the battery input/output terminals and wouldn't start working until the battery terminal voltage got up to about 10V.
Is this true in general? Not sure how to find out as I don't think that the Blue Sea manual ever said much about this. And I don't want to spend a bunch on my system. I will have $20 invested in the dehumidifier, $80 for the 100W panel and would like to use a cheap Renogy controller or similar.
And finally is there any battery (cheap of course) that can stand discharging every night to about 10 volts where the controller cuts off and back up again in the middle of the day.
More to come tomorrow when I report how the little dehumidifier dealt with the humidity on my boat.
David
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