Posted on 09/12/2025 4:36:17 PM PDT by eastforker
Trying to figure out how much battery storage, inverter size, type of charger and what have you to power my houseboat. My plan is to have enough battery storage to run everything using an inverter for AC power using batteries and by charging those batteries daily using a generator for a few hours. The biggest draw would be an occasional few minutes of a microwave to heat food, and also run a tv/monitor along with computer. everything else runs on DC current for short periods of time like fresh water pump. I do have a small a/c air conditioner that pulls maybe 8 amps. Pretty simple setup but also need to know if lead acid batteries are sufficient or do I need special batteris. Any help would be great.
Yes, I am running 6 deep cycle marine and 600 watts of panel and never have to start the (12v) generator except if I get a couple cloudy days. I use my laptop, run the radio or TV, lights, microwave, fridge on 12v, just as one would in a normal home. And I could actually get away with only 4 batteries.
As you know, there is a fine line between battery/panel ratio. Too much battery and they do not fully charge during the day. To much panel and you are wasting free energy. So there is a balance to it. I would suggest to the OP for his rig 4 deep cycle marine batteries and 600 watts of panels would be a good balance.
Unfortunately the problem is over time all the sulfur cooks out of the electrolyte, turns to a solid, and settles on the bottom. so it is hard to get much more than that. You could dump it all out and refill it with new electrolyte but it is not worth the time, trouble, and added cost of electrolyte, disposal, labor, etc.
If you do the math. It is just cheaper to get new batteries for $100 a piece and be good to go for another five years. I don’t know how many batteries you have but I have 6. So my “power bill” is $120 a year for five years of life. Or $10 a month if the batteries cost $100 each. We get marine batteries from Walmart for that price because we are a boating area.
How much area does 600 watts of panel need.
hmmm, I solar powered my well because it was well over $100K to bring power to it, I also got fed up with all the APU’s they sell for computers, none work for much more than an hour and of course the software NEVER worked with server 19, I had 2 dns and 1 mail server.
Well
1 Magnum MS4024PAE 240 grid tie volt Inverter
8 225 AmpHr 6 volt golf cart batteries
8 350 watt solar panels
1 MPPT Solar Charge COntroller/
this setup runs wy well for up to 2 hours a day flawlessly using less than 20% of storage, actually only runs 1 hour every other day on average, works absolutely great and was well worth the $5000 it cost me to build.
Server Backup for 3 servers
1 Magnum 120 volt/24 volt grid tie inverter(dont remember model)
4 225 amphr 6 volt golf cart batteries
wired to wall socket to keep batteries fully charged.
this will keep all 3 servers running for over 24 hours without a hitch and switchover is fast enough to not even cause a glitch in computers, ready for solar panels if wanted or needed, but grid tie works where I have it just fine.
Solar Power is NOT a panacea, but depending on what you are looking for, it can be a godsend.
Hold on, let me go measure mine... BRB
Here is what Grok AI said about your post;
Step 4: Inverter Sizing and TypeThe inverter converts 12V DC battery power to 120V AC for microwave, TV, computer, and AC unit. Size for surge (startup draw, 2-3x running watts for motors like AC compressor).Peak Load: Microwave (1,000W running, ~1,500W surge) + TV/Computer (150W) + AC (960W running, ~2,000-3,000W surge if compressor starts). Worst-case simultaneous: ~3,000-4,000W surge.
Continuous: ~1,500-2,000W (e.g., AC + TV).
Formula: Inverter Watts = (Highest Surge Load / 0.85 Efficiency). Aim 20% larger than max continuous for safety.
Recommendation: 2,000-3,000W pure sine wave inverter (e.g., Victron MultiPlus or Xantrex Freedom). Pure sine is essential for sensitive electronics (TV/computer) and efficient AC/microwave operation—modified sine can cause humming/overheating. 2,000W handles most; 3,000W if AC surges high.
Include a transfer switch for seamless generator/shore power integration.
DC draw: A 2,000W inverter pulls ~170A from 12V batteries (use 2/0 AWG cables, fused at 250A).
Step 5: Charger Type and SizingYou’ll charge batteries daily via generator (AC output to charger). Use a smart multi-stage charger for safe, efficient charging (bulk/absorption/float stages).Sizing: Match to battery bank (C/8 rate, where C = Ah capacity). For 300Ah bank: ~40A charger. Generator must support charger + loads (e.g., if charging at 40A while running AC, total ~1,500W+).
Type: Inverter/Charger Combo (e.g., Victron MultiPlus): Best—one unit inverts and charges (80-120A models). Auto-starts generator on low battery.
Standalone AC-DC Charger: Simpler/cheaper (e.g., Progressive Dynamics 40A, $200-400). Lithium needs a dedicated profile (no equalization stage).
Daily Runtime: For lead-acid, 4-6 hours at 40A to recharge 50% DoD (full charge takes longer). Lithium: 2-4 hours. Run generator at 50-75% load for efficiency (quietest/fuel-saving).
Generator Note: Size 2x inverter continuous rating (e.g., 3,000-5,000W Honda EU series). Quiet marine models (e.g., 3,000W) suffice; add auto-start if using inverter/charger combo.Step 6: Overall System TipsTotal Cost Estimate (Basic 12V Setup): $1,500-3,000 (200Ah lead-acid bank + 2,000W inverter/charger + wiring/fuses). Lithium: +$500-1,000.
Wiring/Safety: Use marine-grade tinned copper wire (e.g., 4/0 AWG for battery-inverter). Install fuses/breakers (e.g., 300A ANL), battery isolator, and low-voltage disconnect (12V). Ground chassis to boat bonding system.
Add-Ons: Battery monitor ($100-200). If space allows, add 200-400W solar panels (~$300) for partial daytime charging, reducing generator hours.
Testing: Start small—install and monitor for a week. Adjust based on real data.
Professional Help: Consult a marine electrician for install (vibration/moisture risks). Check local codes for houseboats.
This setup should give you reliable power with 2-4 hours generator runtime daily. If your AC is DC-native or usage changes, recalculate. For specifics, provide exact appliance models!
OK, I have four 150 watt panels and they are 32”x64” each. These are home system take offs. They make some 150 watts that are slightly smaller but not much.
Now let me share about these home take offs. If you are patient and keep an eye on Craig’s list they give these things away to get them out of their garage.
They age and then solar companies sell them new panels for their home systems. These home take offs are absolutely still GREAT for 12v or 24v systems!
Desulfate your batteries and they will last longer.
So they would fit on the 10X8 foot roof of cabin.
This last batch of free panels I got there were 16, come haul them away. :)
So use what you need and share with friends... :)
“So they would fit on the 10X8 foot roof of cabin.”
Yes, fine the 8 foot width, and just a couple inches hanging off the 10 foot length. But you might find some 150 watt panels slightly smaller. The newer models are smaller and put out the same wattage.
1) IMHO post #10 is wise. Start there.
2) Before going into the calculations below, I'll add here that you can always make sure your equipment is stackable to upgrade later if you need to. For example, if buying one small battery and trying it for a while doesn't work, fine. You can add a second battery later on a bus. Same with adding a solar panel later. With my experience, my math in the planning state you're in but for my home was fairly accurate, but I started with a much smaller system for a year than I knew I'd want in the end just so I could see how it handled all seasons. After that I upgraded it to the system I have now. In your case, perhaps the only thing that would be important to make sure you get right the first time is inverter/charge controller capacity. (I later added a 2nd inverter, but I have more room in my garage than you have on a houseboat.)
2a) I'm a data-centric person. I'm happy with my Sol-ark inverter (later upgraded to 2 inverters) in large part because they record telemetry every 5 minutes that I can export into Excel spreadsheets and import in a SQL database and crunch numbers. A year's worth of data for all 4 seasons in different weather helped me see exactly how much of each solar component I should upgrade to take advantage of the economies of scale (invest more to get higher ROI), but not so much I'm fighting the law of diminishing returns (invest more gets lower ROI). Basically, I win the battle on the averages without trying to be completely off grid. Much like you'd probably be willing to use your generator every now and then, but would like to minimize when feasible. If you're not quite that heavy on raw data, I suggest at least get an inverter that provides a few graph outputs so you can see it summed per day, per month, etc.
3) Another tip is to be hip to how much the peak solar hours change per month in your area. Use this tool, enter your city, then click Results. For me it says in January I get 3.4 hours, February I get 3.9 hours, etc. (numbers below assumes yours is the same) Let's say you calculate from post # 10 that on an average day in January you consume 5 kWh and want to know how much solar you'd need to handle an average day in January. 5 kWh / 3.4 peak solar hours = about 1.5kW (1500W) of solar panels. Assume a 10% reduction converting DC to AC. (You'd need 10% more panel wattage just to break even on an average day, so call it 1,650W.) Repeat that for all 12 months. Of course, include a little extra for margin. (Unless you're trying a small system for a year like I suggest in step 1.)
4) Battery storage: Assume another 10% loss when storing power to the battery, it sitting for a while until night, then later retrieving the power from battery. In all of 2024, the amount of power I discharged from the battery stack was 9% less than the total stored to the battery stack. Of course not all of the solar power coming in would go straight to battery because some would be immediately converted to AC to power the load. So you don't need your entire battery stack for the 24 hours of power consumption. But you do need extra solar wattage intake knowing that the night time power consumption will first go through a 10% loss for storage, before going through another 10% loss converting DC to AC like daytime power does too.
5) Depth of discharge and wear on batteries: The way I handled it for my home was to simply buy more battery storage than I usually need to power through the night. But I have more room in my garage than you do, so maybe it's not as easy for you. I've set my inverters to not let my battery stack to get below 30% charged before they start pulling from the grid (again you won't have a grid, but you might decide a similar floor before running a generator). Yet, my system usually doesn't drain below about 45% or 50% anyway. So usually (not always), I'm not taxing my batteries a lot with a huge depth of discharge. The hope is that this makes them still working well beyond their 19-year/50% usable warranties.
6) If you have something else on your houseboat that's battery powered that you don't have to charge all the time (i.e. hand tools, electric shaver and toothbrushes), you might consider an inverter that has what my Sol-Ark calls "smart load". Though this isn't exactly how you'd use it, here's how I do it. When my battery stack is at least 70% charged (or whatever I configure it to different times per year), my inverters will power an intermittent electrical panel that I use for usually charging my EV. The idea is that if my home battery stack is charged to 70% or more, my home will power through the night without pulling from the grid nor draining my battery stack too much on average. Combine that with the fact that my EV doesn't need a charge every day (230 mile range if charged to 80%, and we drive it about 50 miles per day, so we can have a few days in a row of hard rain before we give up waiting for free solar and decide to charge the EV with grid power). Thus we usually keep the EV plugged into a charger from the intermittent electrical panel (not always on, but if it is on it's always free power). But if we come home in the EV with less range than we need for the next day, we charge it with a charger tied to the constantly powered panel (always on, but not always free). The end result is our EV is almost always charged with free power. Basically, my EV's battery acts as a kind of extra storage for my home (though my home is never powered from the EV battery, just saying the math and usage make them work in concert).
Now using the example above, but for you without an EV. If you have some 120V outlets in your houseboat that are intermittently powered, next to outlets that are constantly powered, you can charge your battery powered hand tools, emergency jump box, hygiene battery tools, phones, laptops, etc. (anything with its own battery) almost always by simply keeping them plugged into the intermittent outlets. If on a string of rainy days you need to charge those hand battery devices, then plug them into the constantly powered outlets. So you have dependable power when you need it, but yet winning on the averages by utilizing intermittent free power when you can (for devices that give you flexibility because they have batteries).
On my 43’ sportsfisher, I consume about 10 KW per day. My house bank consists of 3 lithium iron phosphate batteries, each 460 AH at 12V for a total of 16560 KW capacity. My inverter charger is a Victron Multiplus 3000.
AC requires a lot of amps when it starts, unless you add a soft start device. I have never tried to run it on the inverter.
Trying to figure out how much battery storage, inverter size, type of charger and what have you to power my houseboat. My plan is to have enough battery storage to run everything using an inverter for AC power using batteries and by charging those batteries daily using a generator for a few hours. The biggest draw would be an occasional few minutes of a microwave to heat food, and also run a tv/monitor along with computer. everything else runs on DC current for short periods of time like fresh water pump. I do have a small a/c air conditioner that pulls maybe 8 amps. Pretty simple setup but also need to know if lead acid batteries are sufficient or do I need special batteris. Any help would be great.
To power a houseboat with battery storage and an inverter for AC appliances using daily generator charging, the most important factors to decide are battery capacity, inverter size, charger type, and whether to use lead-acid or lithium batteries. Lead-acid batteries can work for simple setups, but lithium batteries offer significant efficiency and lifespan advantages for marine use.
Core Components and Sizing
Battery Storage Size
For lead-acid batteries, only about 50% of their stated capacity can actually be used (Depth of Discharge, DoD), so you need double the storage for your daily energy demand.
Example Calculation: If your daily usage is about 3,000Wh (microwave, TV, monitor, computer, small A/C), you’ll need batteries with a minimum rating of around 6,000Wh (or 500Ah at 12V).
For lithium batteries, you can use up to 80-100% of their rated capacity, so you’ll need less overall battery (e.g. 3000-3500Wh for the same usage).
Inverter Size
The microwave is typically the largest load, requiring an inverter rated at 1800-2000W (pure sine wave type).
TV, monitor, and computer can be run off smaller inverters, but if combined with the microwave, the total inverter size should meet or exceed the microwave’s surge requirement. For a standard 1000W microwave, a 2000W pure sine wave inverter is usually necessary for safety.
A/C units that pull 8 amps at 120VAC = 960W; check their startup surge rating before sizing inverter.
Charger Type (for Generator Charging)
Use a smart charger or inverter/charger sized for the capacity of your battery bank. Match the maximum charging rate allowed by the batteries so you can charge efficiently in a few hours.
Lead-acid batteries accept lower charge rates; lithium batteries can accept higher currents and charge faster.
Lead-Acid vs. Lithium Batteries
Feature Lead Acid Lithium (LiFePO4)
Cycle Life 300-500 cycles 3,000–15,000 cycles
Usable Capacity (%) 50% 80–100%
Weight (100Ah) ~30 kg 10–13 kg
Maintenance High Low
Charging Speed Slow Fast
Cost Low Initial Higher Initial
Lead-acid is budget-friendly for basic setups with low cycle demands. Lithium (LiFePO4) batteries are recommended for longer lifespan, lighter weight, deeper discharge, and faster charging, especially for frequent use or higher daily energy loads.
Quick Recommendations
Battery Bank: 500Ah (12V) for lead-acid, 250–300Ah (12V) for lithium, based on 3–3.5kWh day usage.
Inverter: 2000W pure sine wave inverter, minimum, capable of surge demands of microwave and A/C.
Charger: Match battery bank and generator output. Smart charger with proper amps for lithium or lead-acid type.
Microwave Use: For brief microwave use (1000W) and AC appliances, the inverter and battery bank as above are sufficient.
Practical Notes
Always size your system for worst-case peak power (e.g. A/C + microwave running briefly together).
Use fused wiring and marine-grade cables for safety.
Lithium batteries require compatible chargers/inverter settings and are initially more expensive but offer clear benefits long-term.
For occasional generator charging (daily or every few days), size for full recharge in 3–4 hours.
Lithium batteries (LiFePO4) are strongly recommended for a houseboat setup where weight, longevity, and recharge speed are important, but lead-acid can work for basic or budget builds.
A setup with a 2000W pure sine wave inverter and 250Ah lithium battery bank (or 500Ah lead-acid) will cover your described loads, allowing daily generator charging for AC power on your houseboat.
Thank you that info has been very helpful
yes. i had to remember never to run the micro and ac together when on generator.
Forget about the microwave. Also, you need to run 12v appliances and lighting. Keep your inverter aside for just those devices which require 110v. Run all your regular stuff off 12v.
Yeah, don’t run a genset at night while anchored—very antisocial behavior.
I just acquired the 2500X/Sidekick package.
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