"The dream" was originally defined as being able to head off into the sunset, exploring deserted beaches and uninhabited islands. Whether gunk-holing or exploring the ICW, at some point spending the night on the hook will be necessary, whether due to the distance between locations, to save $$ (transient slips are expensive!), or just for the hell of it.
In Texas (and many other places in the summer), spending the night on the hook requires air conditioning. For trawlers, running the air conditioner traditionally meant running the generator. But the generator is LOUD, vibrates the whole boat, and gives off exhaust. On Sunset Dream, the generator has not worked since well before I bought the boat. It will start. It will even generate electricity - as long as you hold the "stop solenoid" to prevent the generator from shutting itself down. The previous owners had at least 3 separate visits from technicians to repair the generator. The typical sensors (over temp, low oil) were replaced. The fuel solenoid was replaced. The main control board was replaced. (And, the wiring harness between the generator and the main breaker panel was removed...) No luck. I spent time with a different technician checking the sensors, checking the control board. No luck. I even sent the control board back to the manufacturer for testing - they reported that the control board passed all tests.
Now, even if I do explore further and find the answer to getting the generator to run (and keep running) - then there is more. The water pump is leaking, and will need to be replaced (not a deal breaker, but more...). There is a water leak somewhere else in the system that needs to be tracked down and fixed. And then, once the generator works - it must be maintained. The generator needs to be started and run on a weekly or at least bi-weekly basis to ensure it keeps working. The sea strainer needs to be periodically cleaned. The oil needs to be changed. The impeller needs to be replaced. All this upkeep for the occasional overnight on the hook.
This section will explore possible experiments and research data to determine whether there is a way to sleep comfortably on the boat without needing to run the generator.
I mentioned above the need for air conditioning. Personally, I won't sleep well if the inside boat temp is 80F at night... The other primary AC load is the refridgerator (there is actually a primary and a small secondary refridgerator on Sunset Dream). I currently use an APAP machine at night. That could be run on a separate battery/inverter if needed. And there there are small loads like the Internet device (Tmobile Home Internet, or StarLink).
There are options for air conditioning:
The obvious solution (if the generator was runing) would be to run both marine air conditioning units - a 16,000 BTU system in the main salon (also cools the forward cabin), and a second 10,000 BTU system in the aft cabin.
Next option is to only run the 10,000 BTU system in the aft cabin, allowing the main cabin to stay warm.
Another option is using a small window unit, portable room air conditioner, or possibly a roof-mounted system in the "escape exit" of the aft cabin. The idea here is that a smaller AC would use less power than the 10,000 BTU marine system.
How much power are we talking about?
The marine air conditioners can be expected to draw 9-15A at 120V. In the heat of summery, these can be expected to run nearly constantly. This needs to be measured. Assuming 10A at 120V, that's 1200W
The refers typically draw about 1A at 120V, so assume about 100W each. This assumption needs to be checked, and needs to be monitored over a couple of days to get an average power usage number. NOTE that the refers run 24/7 - Not just at night! They can be unplugged for several hours at a time and stay cool enough - but for planning purposes, we will assume they stay plugged in.
The APAP machine probably draws 100W or less when running. (This needs to be monitored for several nights to validate.)
A 5000 BTU window unit draws about 600W. If this is sufficient to cool just the aft cabin (with the cabin door closed) for moderate portions of the summer / fall, that would save a tremendous amount of power.
For an 10 hour period at night, assume:
600W AC
200W Refer
7 cu ft Norcold fridge: Max 79.2W high, 5.4W low Average for 13 hours was 43W/hr(?) Need more data
This was collected in the WINTER time (Jan '24, cool weather)
Sunset Dream has 2 refers - so 200W estimate isn't wildly high.
50W APAP (APAP is typically only used about 5-6 hours at night)
45W highest consumption; Standby / lowest: 4W
Average about 24W/hr during run time. (based on 3 points)
150W lights, pumps, internet
TOTAL: 1000W @ 10H >> 10,000WH (assuming no losses for the inverter.
At 12V, this is about 833Ah. A bank of 3 or 4 x 400Ah lithium batteries would be nice...
Water Heater:
1300W, 11.5A peak Need to collect data on the percentage that the water heater runs... And experiment with what we can get away with, and see how long it takes to heat up from cold, and how long to heat up from being off overnight...
WINTER:
For mild winter temperatures, the boat can be heated with two oil filled space heaters, running at 700W each.
One could consider a single heater in the aft cabin, or setting the heaters to run on low (300-400W range) with a 100W electric blanket.
COOKING - All of the above ignores cooking requirements. Sunset Dream has a fully electric galley. There is the original stove with oven burners (that do not work well), a 700W microwave, and a 1500W induction stove top.
One of the previous projects on the boat was to update the electrical system. When I bought the boat, there were two batteries - each a single 8D. The batteries ended were connected in parallel using the battery selector switch. Both batteries in parallel were used to power both main diesel engines, as well as the house needs (lights, pumps, etc).
The following steps were taken:
The 8D batteries were removed and replaced with new golf cart batteries (each side now has two 6-volt golf cart batteries in series to provide 12V for starting the engines). The starting banks are isolated. The starboard battery has a trickle charger. The port battery relies on the engine being periodically started to allow the alternator to keep the battery topped off (just like a car). So far, the trickle charger for the starting bank doesn't appear to be necessary.
A 150AH lithium battery was added as an isolated house battery. This was upgraded to a 400AH lithium House battery.
A Renogy DC-DC charger was added to allow charging the lithium house bank from the starboard engine when the boat is under way.
A Victron battery monitor was added.
A 3000W inverter was added, though not wired to the house system at this time (inverter has two outlets).
From research, I'm making the following assumptions:
Assuming 6 hours per summer day of charging (probably a lot more, but assuming 6 hours as much of that time will be at lower power levels). This is a WILD guess...
Assuming panels to actually yield 65-75% of their rated power (based on head to head tests of 200 and 400W systems).
Upper and lower biminis both have at least 8' by 8' (96" x 96") of usable space for solar panels
As a simple example, consider BougeRV 200W flexible solar panels
28" x 87"
about $600
3 panels can easily fit per bimini
3 x 200W = 600W, x 2 biminis = 1200 max rated watts.
1200W * 65% =~ 780W
780W * 6 hours =~ 4680WH =~ 390Ah @ 12V
Assuming 80% efficiency and 7 hrs of charging, we still only get to 6720WH - not enough to run overnight.
Conclusion: This is busted. There is no way to put enough solar panels on the boat to charge the batteries to run overnight.
2000W portable generator
Assume 1200W usable, constant load
1 generator running for 8 hours would generate 9600WH. Assuming NO LOSS, this could charge a house bank enough to make it overnight.
3500W portable generator
Assume 2400W usable, constant load
Can we set up a battery charging system that can charge the battery bank in excess of 1200 to 2400W?
1200W @ 13V =~ 92A
Can (4) 50A chargers be connected to charge (4) x 400A batteries in parallel?
A 70A charger can charge about 1000W into the battery from a 1200W AC source.
Can a 70A AC charger be connected in parallel with a MPPT charger?
Is there any way to switch between 400A banks?
Splitting banks...
If we isolate the AC - then it's 600W @ 8 hours >> 4800WH >> Almost in the range of a 400AH battery. Within the range of 2x300AH battery bank. This could be charged in 5 hours with a 1000W source.
Sunrgy Solar Distribution; 832-768-5050 https://g.co/kgs/BRtNJYS
Signaturesolar.com
EG4-3000 - combo inverter / mttp charger
EG4-6000xp - Combination inverter/mttp charger
Above two from: https://eg4electronics.com/
Solar power alone is not sufficient to run AC and other power needs overnight.
Solar supplemented with at least a 2000W portable generator could charge the batteries enough to run overnight.
A 3500W or more generator could charge a LARGE battery bank sufficiently to run overnight (assuming large enough chargers could be found...).
For more details, see Sunset Dream log, 5/2/24
AFT Marine AC unit - Dometic 10,000BTU, with 1000GPH water pump running:
Approximately 900W at inverter (including inverter load)
Honeywell Room AC - 8000BTU Model HF8CESVWK5
Max observed approximately 890W (7A @ 115V) on power meter (without inverter load)
Also observed 600-650W nominal at low compressor / fan load.
Walmart Midea 5000BTU window unit
Approximately 600W
8/11/24
Ran a "proof of concept" test to validate running a 5000BTU room air conditioner on battery.
AC: Vissani 5000BTU Model #VPMS05BWT
Inverter: Ronpow Pure Sine Wave 3000W (6000W peak), ($160 Amazon July 2024)
Battery: Eco-Worthy 150Ah LiFePO4 12V, ($520 Amazon June 2022)
Test 0:
Attempted running Vissani 5000 BTU unit on house 400Ah bank with 3000W inverter.
This test failed. The wire length through the house wiring, breaker, etc, and up to the inverter was too long and wire gauge too small. Under the 900W load, the voltage dropped badly enough that the inverter very quickly tripped (10-20 min).
For this test, the inverter was wired directly to the battery (no breaker, no fuse - direct test under direct observation) with 2' cables (4 ga?)
Voltage read from the inverter was consistent with voltage measured at the battery. 0.06V drop measured, comparing battery voltage to voltage at inverter terminals. Voltage in the table below was from the Inverter display.
NOTE: "Ground" terminal on Inverter outlets appears to not be wired to anything. Power strip was plugged into invert, jumper plugged into power strip that connected neutral to ground, then Kuman AC power monitor plugged into inverter, and Air Conditioner plugged into power monitor.
AC TEST 1
Time Voltage Watts Volts AC Power Meter Watts
11:31am 12.7V 869W 117Vac 795
12:01noon 12.6 816 117 737
12:32pm 12.5 817 117 741
1:04pm 12.3 812 118 732
1:18pm 11.8 828 117 745
1:23pm Inverter dropped offline (Battery BMS tripped - Low voltage presumed)
After the test, the AC power meter indicated the following: 1.45Kwh total consumed, 827W peak.
Assuming 1.75 hrs for the test duration, average consumption was about 830W.
Note - Using an approximate average of 70A draw from the battery at 1.75 hours, only about 120Ah should have bee drawn from the battery. This is disappointing for a 150Ah rated battery.
Conclusion: It is certainly possible to run the Vissani 5000 BTU room air conditioner on a 3000W inverter, supplied by a 12V LiFePO4 battery bank.
To be able to cool the aft cabin of the boat during the night, one might extrapolate a usage of
850W x 8 hours = 6800 WH. 6800Wh / 14V =~ 490Ah
850W x 10h = 8500W / 14V =~ 607Ah
AC Test 2 (Running on Shore Power)
Reset AC power meter.
Test started at midnight. 84F outside temp. 75F inside temp
Vissani Air Cond, 5000BTU run in main cabin on shore power.
12:00am midnight - test started
8:00am 5.105 kWh, 6.4A / 715W (instant) - 813W peak, 112V - avg 640W
10am 6.472 kWh - avg 647 W
11am 7.112 kWh - avg 646 W
12noo 7.738 kWh - avg 644 W
AC Test 2 (Running on Shore Power)
11pm Test started - 85F outside
9:00am 6.15kWh ~ 620W average running through the night.