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.
You can actually plug that question into AI. I have no clue of the answer. But I do know how to plugin a question to AI
Is the AC going to run 24/7 on a hot day?
I would say probably during the day.
I have some knowledge, but will not ever claim to be “an expert “. Further, I fully expect others to be more knowledgeable.
But. What is your highest load, expected average load, and minimum load. What frequency AC and voltage to be delivered? Automatic and continuous service? Or irregular with you turning switches and breakers on and off - as at a vacation house or disconnected work shed away from the grid?
DIY Solar Power with Will Prowse
I bought the book in the third link and used it to set up an emergency solar system for our house.
They have a marine forum...might be helpful for non-solar applications/questions too...???
I would say the fridge, 24/7, an LED tv and esk top computer also most of the day and then the small air conditioner through the hot part of day.
You need to add up all of the watts of the things you are running. Then multiply by the hours you will be using them. That gives you the watts/hr.
Trying to keep batteries charged to power that stuff is going to go through a ton of cycles. That wears out traditional batteries.
You will need deep cycle batteries or those used on solar applications.
Your issue is going to be in trying to keep those batteries charged. Depending on your location, it might actually be a decent case for a small solar set up.
Wattage is voltage times amperage. If you need 1000 watts at 120 volts, your current demand is 8.3 amps on the 120V side. You will require 1180 watts on the battery side. With a 12V input that requires 98 amperes. A 24V input would require 50 amperes. Scaling to higher wattage is linear.
Just one battery?
Wouldn’t a generator a few hours a day keep them charged?
This is the main variable. Need a better estimate.
One thing I did learn from Will Prowse is that the higher voltage battery you use the lighter the copper wire you need to use, and copper wire can be expensive. I wound up with 48 volt batteries.
You need to first start by determining the running watts of each of your electricity usages. Then determine the number of hours that each of them will run each day. Add all the watt-hours together to find out how many watt-hours of battery you will need. remember that batteries generally can be charged to only 80 percent of capacity and shouldn’t ever be discharged below 20 %. This means that your batteries need to have 40 % more capacity than you use.
Lithium iron (not ion) batteries last far better than lead acid for long term use. If you can run your boat off the generator while you are charging the batteries, you can subtract off the hours that the batteries are charging.
Food luck
I call Will the “Elon of solar” when referring to solar and backup battery based power systems.
He covers everything from whole house to camping power systems.
Supplies and equipment recommendations are also provided.
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It’s the repeated process of charging and draining on a daily basis that is going to “wear out” the batteries. That is why you need expensive batteries to handle that kind of “up and down.” Most batteries are not for such prolonged use. Marine and auto batteries are constantly being trickle charged through the engines. That is why I thought solar which would trickle a little charge all day into the batteries to keep them topped off.
That was my idea to run the generator in the morning while underway and then use battery power overnight while anchored. I plan on running up and down the Tn river a few hundred miles for a few months.
It’s all about input versus output.
I would use AGM batteries because they provide high current output for extended periods and don’t require maintenance.
I use them all the time for battery backups.
Freepmail me if you would like some equipment suggestions.
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