New Lithium setup for off grid cruising - and air conditioning

[Seafarer7]

Here’s a Velair i16VSD 16K BTU running off solar + batteries
https://youtu.be/ZO2QtztkyHY


Basic System Overview:
- solar: 1335 watts total (3 x 445w solar panels, each with a separate MPPT controller)
- battery bank: 1250 AHr (5 x 8D AGM)
- inverter: 3000w pure sine wave

Test Conditions:
Hot August day, little wind, average sunshine; SF Bay Area;
Velar AC (+ AC circulation pump) running off inverter,
Velair AC set to cool mode, target temperature 72’F (~22’ C)
When the cabin cooled down to the target temperature, the Velair AC switched to low cool mode, with pump and variable speed compressor still running but at a lower frequency and lower power, to maintain the cabin at 72’F

Test Results:
(b) Inverter DC current: from 27amps to about 31.55 amps (only about 370 to 430 watts total for both Velair AC and circulation pump)
(c) Solar controllers generating total of about 47 amps (640 watts)
- with the battery bank held at Float, the solar charge controllers were discarding (ignoring) about 200+ watts. (Ie: harvesting only 640 watts out of possible 840+ available watts)

‘Extra’ harvested solar charge: 47 amps - 31 amps = 16 amps, used to hold batteries at float and to power rest of the DC systems on board (fan, music, nav equipment, etc).
Unharvested solar: About 15 amps solar potential amps was being discarded (ignored energy) since batteries were full and already held at float.

[fivecapes]

Originally Posted by Seafarer7

...with pump and variable speed compressor still running but at a lower frequency and lower power...

If this is the raw waterpump, are you saying the unit is able to lower its frequency and power, if so, how?

[Networker]

The price is nearly the same, so I could go with the i16. How much battery and solar do you have?

[Networker]

Originally Posted by Seafarer7

Here’s a Velair i16VSD 16K BTU running off solar + batteries
https://youtu.be/ZO2QtztkyHY


Basic System Overview:
- solar: 1335 watts total (3 x 445w solar panels, each with a separate MPPT controller)
- battery bank: 1250 AHr (5 x 8D AGM)
- inverter: 3000w pure sine wave

Test Conditions:
Hot August day, little wind, average sunshine; SF Bay Area;
Velar AC (+ AC circulation pump) running off inverter,
Velair AC set to cool mode, target temperature 72’F (~22’ C)
When the cabin cooled down to the target temperature, the Velair AC switched to low cool mode, with pump and variable speed compressor still running but at a lower frequency and lower power, to maintain the cabin at 72’F

Test Results:
(b) Inverter DC current: from 27amps to about 31.55 amps (only about 370 to 430 watts total for both Velair AC and circulation pump)
(c) Solar controllers generating total of about 47 amps (640 watts)
- with the battery bank held at Float, the solar charge controllers were discarding (ignoring) about 200+ watts. (Ie: harvesting only 640 watts out of possible 840+ available watts)

‘Extra’ harvested solar charge: 47 amps - 31 amps = 16 amps, used to hold batteries at float and to power rest of the DC systems on board (fan, music, nav equipment, etc).
Unharvested solar: About 15 amps solar potential amps was being discarded (ignored energy) since batteries were full and already held at float.

Amazing!

[Seafarer7]

Originally Posted by fivecapes

If this is the raw waterpump, are you saying the unit is able to lower its frequency and power, if so, how?

There is a 115v raw water circulation pump KoolAir 500gph (https://www.amazon.com/dp/B01G3XCFUU) that is powered via the Velair AC. However I don’t believe the Velair AC lowers the power of the pump: it seems to run at full mode whenever the AC compressor is running. However this pump uses only about 120 watts.

The power savings and zero surge-starting current come from the variable speed AC compressor (and AC air blower fan): those get throttled down in power and frequency.

The compressor speed can range from 100hz down to 20hz, drawing as low as 2 amps @ 120v ac (or just 240 watts) at start up or low power mode.

[Networker]

The Velair 10i is about $2200 and I really want this one, and it will cool my master cabin just fine and it runs ultra efficient, on average, 4-5 amps through inverter, or about 620w hours on average. I think it will be underpowered if I use it for both the salon and master cabin though. So then I should just get the Velair 16i, which is nearly the same price, about $2400. It’s got good size and will keep the boat fairly cool (a 16k BTU is what I have now), and it’s going to average about 6-7 amps, run through inverter. I think it will be about 950w hours once you take the inverter penalty into account. I think it will be about 40% more efficient than the Dometic I have now and the same price, which runs at 1400w hours.

Overnight (8 hours), I think the 10i will draw about 5k watts while the 16i will draw about 7.6k watts. My current unit draws 11.2k watts, so it’s a good upgrade.

However, I am investigating the Marbu 12v DC 12k BTU unit and it’s my first choice. It runs at 30-40 amps while cooling, dropping closer to 25 amps once it hits its cooling point. So watt-wise, should be 400w hours (+- 50) depending on where it is in the cooling cycle. Because it’s DC, there’s no inverter penalty. So overnight it will draw about 3.2k watts. The downside to the Marbu is that it’s an eye watering $4500, but I think this is the only way to do it and not freak out watching my batteries get drained each night.

[Networker]

Originally Posted by Seafarer7

Networker: if you have the space and budget for it I recommend the i16k Velair, not the 10k. That way you retain the full btu range: 3000+ btu to 16k btu. I can easily run my i16k indefinitely off of solar + inverter on a good day by tuning down the btu/power to low mode, such that it’s under 400 watts, well below the solar output (>1kw). On my last test the Velair was running (low mode) and I still had excess power (the solar controllers were discarding excess solar while holding the batteries at float)

Do you think if it only ran on low power/cool mode, it will cool the boat down, or does it have to start in high output mode to cool down first, then go into cool mode to maintain the temperature?

[Seafarer7]

Originally Posted by Networker

Do you think if it only ran on low power/cool mode, it will cool the boat down, or does it have to start in high output mode to cool down first, then go into cool mode to maintain the temperature?

There’s at least a couple ways to get it into low power mode:
- automatic (“A”) mode: AC may start out in full power mode and then throttle back power when it approaches target temperature
- manual (* or **) mode: you can manually set it to fan speed 1 or 2, and the AC compressor will throttle down as well, and stay low regardless of temperature target being attained.

In the first (auto) mode it likely will cool down your boat (or keep on trying at full power).

The second mode is the equivalent of having a lower effective BTU AC. It may or may not cool your entire boat depending on the boat area, heat intake rate vs effective btu rate, but the power usage will be significantly lower than full mode. By switching to manual mode * or ** you are in effect changing your i16k btu AC to an i10k btu or lower AC, with a corresponding reduction in power. Other than price and size I don’t see much advantage to the i10k since the i16k can be manually dialed back to use as much or less power.

[Steve_C]

Mabru is working on a 17K 24v DC unit that is supposed to be available early next year. I have no specs on it other than the above. I am very curious to see what it costs and full specs. I take delivery in Late Jan next year and so timing may be good.

[Networker]

I just visited them to pick up my 12v AC. They were supposed to get some 24v ones yesterday but didn’t arrive yet. They don’t know the final cost until it arrives and they bake in shipping and other overhead they said.

[Steve_C]

Originally Posted by Networker

I just visited them to pick up my 12v AC. They were supposed to get some 24v ones yesterday but didn’t arrive yet. They don’t know the final cost until it arrives and they bake in shipping and other overhead they said.

So you went ahead with the 12K 12V unit? I am really curious to hear how the installation goes and how well it cools. Lots of pictures and reviews please!!!!

[Networker]

Originally Posted by Steve_C

So you went ahead with the 12K 12V unit? I am really curious to hear how the installation goes and how well it cools. Lots of pictures and reviews please!!!!

For sure, if I have time I’ll put it in this weekend, else in 2-3 weeks. I’ll document it with photos and compare it to the Dometic 16k BTU I’m pulling out, which works really well now that I replaced the blower.

[Whatta Life]

Any update on this?

[Networker]

Originally Posted by Whatta Life

Any update on this?

I’ve been in Ghana for work. Will get back next week and wrap it up before setting off for Bahamas in Nov. will share photos and performance once back.

[Networker]

Finally installed the Mabru 12v AC unit and it works as advertised, if not better. We had a 16k BTU Dometic 115v ac unit that was working great, just drew 1450w all the time! We replaced with a 12k BTU Mabru and it cools entire boat better, and is much quieter. The power draw when at full blast is just 525w or so, and goes down to 225 or so when it’s just maintaining temperature. So assume it’s averaging 350-400w, or 30-33ah. At 8 hours at night, that’s just 2800w, or 233ah, which for my boat is completely reasonable. See photos below.

I think I proved it is indeed possible to build a new electrical system of solar and lithium and run AC, and the up front costs are probably the same price as a new genset. The benefits come from no ongoing diesel costs to maintain the system and you have more electricity than you know what to do with to power your other stuff.

P.S. another major benefit of the Mabru is it’s size! We removed the larger Dometic and have a whole storage area free for wine! 24 bottle where the AC used to be.