Liveaboard power requirements

[Silvrav]

I am purchasing a koopmans 38 with 300watt of Solar and 3 x 110ah house batteries. This will give me around 330ah with roughly 155ah usable - that translates into about 2000watts. I am upgrading the solar to 600watts to ensure I can recharge the bank in around 3hours (depending on the day and conditions)

Cooking and water heating are done by gas.

12V TV is around 80watts
starlink averages about 80watts
LED lights - 10watts each (say 5 on at a time) - 50watts
phone/laptop use - 50watts

That totals around 260watts of use per hour. Realistically the TV,laptop use etc won't be on permanently so if I average it out to 200watts I should be able to go 10hours before needing a recharge. Usage will mostly be during the evenings and I am off the boat at work from 7 to 6 daily (except weekends)

Keen to hear others power use and pitfalls so I can plan accordingly.

I am planning to upgrade the battery bank to a LiFePO4 to get more usable energy per battery but that's next years project.

EDIT: to add, the motor has a 100A alternator installed so in worse case scenarios i can run the motor for a bit to recharge the bank.

[akopac]

Hi There Buddy

I am a solar independent single handed world cruiser. I am currently in Whangarei, New Zealand.
After many years of cruising I can say that the main power crushe is not electrically based. It’s insulation around your refrigerator/freezer. I redid my box twice before I got it right. The 1st time was messed up because all that was available was white pellet styrofoam in Mazatlan, MX 25 years ago. Is absorbs moisture and has a low R value. I did post a thread a few years back with load and engineering spread sheets that are very valuable in building out the box correctly o eliminate all 3 types of heat transfer.
LED lights make a big different INCLUDING NAVIGATION & Anchor lights
Gas cooking helps a lot and a pressure cooker is definitely a game changer.
Starlink eats a lot of power and should be only on when using it.
I use a Raspberry Pi and opencpn/plotter for navigation screen sharing to an iPad Air in the cockpit over the pi’s integral WiFi access point ( Openplotter feature). It uses .4 amps@ 12v.
I use a my radar is a B&G halo 20+ and will overlay radar.
I have 400 amphrs of usable firefly batteries and 400 wattts of solar.
My batteries are full at anchor by 10am
Underway by 12pm, if I’m using radar at night they are are full by 1-2pm.

[dougweibel]

600 Watts of solar may be enough but 150Ah of usable battery capacity sounds pretty light. Refrigeration uses a fair amount of power, particularly in warm climates. We might use 150 Ah overnight for the refrigerator, freezer, lights, fans, several hours of Starlink and a cycle of the Instant Pot.

If you run an autopilot on passage that could exhaust your battery capacity overnight for just that use. While not necessarily intuitive being on passage under sail is our worst case energy usage scenario. A couple days of cloudy weather can be very hard on the energy budget also....

[Bowdrie]

Originally Posted by akopac

After many years of cruising I can say that the main power crushe is not electrically based. It’s insulation around your refrigerator/freezer.

Amen, we have a winner.
It was true decades ago, it's still true today.

[George_SD]

I had a single 100w solar panel and 2x100ah house bank batteries +1 engine 100ah . They ran 2x 12v fridges (built-in and a large portable), LED lights, pumps, radio, etc. Never ran out of power in California. But I also don't leave anything except fridges running 24/7. Both fridges were not nearly as well insulated as on most quality boats. Just pointing out that it's really your usage that maters.

I would suggest upgrading batteries before upgrading solar. They give you more capacity to store what solar produces. Remember that everything is fed by batteries, solar just charges them. As long as they are topped off by the end of the day and ready for the night - you are good to go.

[Tupaia]

Using the newish "Flat" orientation setting on Starlink reduces the power considerably.
80Watts seems a lot for a 12v TV what size is it.
You don't mention a fridge or a freezer these are typically large consumers.

[sailorboy1]

[QUOTE=Silvrav;3915991

Keen to hear others power use and pitfalls so I can plan accordingly.
.[/QUOTE]

From my experience full time cruising you can expect to use 150-200ah/day and your current solar will probably do around 100ah/day. But if you are only on the boat on weekends your load drops to only the frig/freezer and during the week the solar will mostly check up (long as as you turn off the SL). I operated for years of weekend use ad 2 years full time with a 290W panel before increasing to 640W.

[Pizzazz]

Since you said liveaboard, the power consumption will be similar to what you use at home if you want to have a quality experience and not constantly monitoring your battery meter and turning off lights and appliances. Coffee machine, icemaker, washing machine... even a clothes dryer. Nothing beats the experience of fresh, dry towels and sheets. These appliances use a lot of power in addition to the fridge. I do not think it is practical to power all of this with solar. I run a 48 ft powerboat with minimal batteries (3 kWh) but I do run the generator when needed at anchor. I estimate daily consumption around 9 kWh including water heater and cooking. You just can't get this from solar/batteries.

[emilecantin]

My boat was just about balanced in the Bahamas with 600W of solar and a 200Ah lithium battery. I shut down Starlink at night to conserve power and it worked pretty well. A few cloudy days would be an issue, though; by the second day I'd need to run the engine for a couple hours to make up for what the solar didn't provide.


Now that I'm back home, my boat is almost overpowered since I don't run Starlink anymore. Battery almost never dropped below 80% during last year's cruise; I never bothered plugging in at the marina.


I'd say you're a bit on the low side in terms of number of batteries, but it'll do for a season. Keep an eye on it and you'll have a better idea of what you need when you switch to lithium next year.


Now would be a good time to invest in a good battery monitor if you don't already have one.

[bergius]

It is hard to give numbers for anybody else. A lot will depend on the equipment, usage patterns, etc. We use a lot more power in Northern European winter than we do in the summer, because of the increased need for heating, light, etc. Similarly, the solar panels produced a lot more in the Baltic summer than they do in generally overcast Scotland.

We have 5kWh of LiFePO4 batteries on board, charged with 660W of solar (360W fixed, rest deployable), a hydrogenerator, and a 80A alternator (charging the bank via 40A DC-DC).

Here are some real-world production numbers from solar, though just for Baltic. Will be interesting to run the numbers for this year when we haven't seen much sun
https://gist.github.com/bergie/d0eda...b49e33853394d1

[S/V Illusion]

Originally Posted by Silvrav

I am purchasing a koopmans 38 with 300watt of Solar and 3 x 110ah house batteries. This will give me around 330ah with roughly 155ah usable - that translates into about 2000watts. I am upgrading the solar to 600watts to ensure I can recharge the bank in around 3hours (depending on the day and conditions)

Cooking and water heating are done by gas.

12V TV is around 80watts
starlink averages about 80watts
LED lights - 10watts each (say 5 on at a time) - 50watts
phone/laptop use - 50watts

That totals around 260watts of use per hour. Realistically the TV,laptop use etc won't be on permanently so if I average it out to 200watts I should be able to go 10hours before needing a recharge. Usage will mostly be during the evenings and I am off the boat at work from 7 to 6 daily (except weekends)

Keen to hear others power use and pitfalls so I can plan accordingly.

I am planning to upgrade the battery bank to a LiFePO4 to get more usable energy per battery but that's next years project.

EDIT: to add, the motor has a 100A alternator installed so in worse case scenarios i can run the motor for a bit to recharge the bank.

No A/C?
No refrigerator or freezer?
No electronics?
No water pumps?
Sounds more like camping than living aboard

[Nicholson58]

Safe to say there is no such thing as too much. We finally achieved power independence this previous season.

All lights are PWM LED
24 volts Frigaboat systems. Battery and solar power 8-9 Ah
660 watts solar panels 3x Sanyo 220H over cockpit
350 watts solar rear arch
Tri-Star MPPT 24 volt solar controller 2016
Epever solar charge controller MPPT model Tracer2206AN
246 V 630 AH Blue Heron LiFePo batteries house bank #1
26 V 105 AH Blue Heron LiFePo dual purpose batteries start bank #2
Balmar alternator charge controllers, main and generator backup main alternator
Blue Sea Charger 3 kw modified full sine inverter new 2016
Samlex 300 watt full sine inverter for small accessories.
Various electronics are always on. Depth, wind, AIS/anchor alarm

Daily use is about 120 Ah at 26.7 volts. Twice weekly we also run the DC watermaker, 6 amps for 2-6 hours.

Located in the Caribbean. Plan to only harvest 50% of your panel rating and only during high sun.

[mark0978]

Living aboard here without needing the genset with 3240 W of solar (more than my batteries can accept).
900AH of lithium going to 1200AH in the very near future (waiting on the battery actually)
We got rid of gas appliances, bought a AC Fridge 11cu foot, super efficient burns about .7KWh/day. vs 3KWh/day for the Italian Boat fridges we had.

What the extra solar has done for us is let us run the A/C during the hottest part of the day. Solar -> Inverter -> A/C all while charging the batteries. I agree that what the OP said sounds more like primitive camping than living.

Max out your solar, as much as will fit, sell the old and get newer, higher capacity panels
Get as much Lithium Battery as you can fit in the boat (the skies are not always clear. You can always increase the consumption if you feel the need, but lacking the capacity can be quite limiting.

We also have a watermaker which is by far the most energy expensive thing on the boat.

[FlyingScot]

Unless those batteries are brand new and of high quality, your usable amp hours are likely way way less than you think.

Your usage will likely be way way more than you calculate.

Unless running air conditioning, freezer/fridge will be the largest load on most boats with the exception of a full size starlink running 24/7.

[westernspirit]

We live onboard May-Sept PNW; cruising 48 to 53 north. 1100 watts solar. In addition to usual including Starlink we have electric galley (induction cooktop, espresso machine, microwave, toaster,)we average around 240 amp hours/day. Highest output from panels has been 750 watts but average is 480 but can drop to 240 in heavy clouds/rain. General rule that has worked for me is daily output = 50% x total watts x 5 hr.
600 Amphr LiPO4; occasionally gets down to 40% but mostly we stay above 65%. In PNW summers you motor a lot and alternator charges but we have hung out on the hook for extended time (weeks) only on solar; no generator onboard and don’t run engine on hook. We do have backup propane for cooking but rarely used.