How to Store Electricity from a Generator for Your Cabin


Using a generator to power your cabin can be really simple and cost-effective.

However, having to go turn on the generator whenever you want power is annoying.  And having to run it constantly while you’re at the cabin can get costly and takes away from the serenity of being in nature.  The solution to this problem is simple.  By using a battery system in conjunction with a generator, you can store all the power you need from running your generator just a few hours per day.  Let me show you how this can work.

The Generator-Battery system

If you have a generator only, you have to have it running whenever you want power.  If you’re running lights and a refrigerator, that could mean constantly while you’re at the cabin.  But even quiet generators have enough of a hum that they’re no fun to have running while you want to be enjoying the outdoors.  They’re not so bad when you’re inside the cabin though.  That’s why the generator-battery system is so great.

By including batteries in your electrical system, you can run your generator just a few hours per day and store up all the power you need for constant use throughout your cabin stay.

Generators can only ramp up and down their fuel consumption to a certain extent, which means that when you have lower power needs, your generator is using more fuel than it needs to for the amount of electricity it’s generating.  By including batteries, you can decrease your fuel usage by storing the excess electricity that your generator produces.

If you’re using a generator to power your cabin and you have regular or consistent electricity needs while you’re there, adding a batter system really is the way to go.

So let’s talk about how much battery storage you need.

Figure out how much power you need each day

To know how much storage to get, you need to know how much you’ll use per day.  The most accurate way to do that would be to add up the average use of all of your appliances and electrical devices.  But that can take a lot of work.

If you just want a round number estimate, you can use a comparable sized cabin or house where you can find out its power consumption and estimate from there.

For example, if your house is 2,000 square feet, has a full sized refrigerator, air conditioner, furnace, lighting on all day, etc. and it uses 1,200 kWh per month then you at least have a frame of reference.  If your cabin is similar in size and has most of the above but no air conditioning, then look at your power consumption in the coldest winter months when the air conditioning doesn’t run.  That might be a good estimate for the power your cabin will use.

If your cabin is even smaller and uses a smaller refrigerator, solar lighting for outside lights, and a propane oven instead of electrical then your power consumption will be even lower.

So again, the most accurate way to determine your power needs will be to add up the usage for all your electrical appliances and devices.  For some examples of how to do that, you can read about it in my article on solar power sizing.

For the sake of this article, we’re going to assume a usage of 500 kWh per month which is fairly average to high usage for a cabin if it has no central air conditioning.  This gives us a daily rate of just under 17 kWh.

Keep in mind that you probably won’t be at your cabin every day in most cases so you won’t actually use 500 kWh of power.  This number is for comparison purposes.  If your house uses 900 kWh and your cabin uses a little over half as much, then 500 kWh is a good number to use to determine your daily usage.  It’s the daily usage number that we want.

How loud and distracting is your generator

If you get a really quiet generator then you can probably make do with a smaller battery.  This is because you won’t mind running your generator for more hours throughout the day.

If your generator bothers you because it disrupts the peace and tranquility of the outdoors, then you’ll want it to run as little as possible.

As you consume electricity, the storage in your batteries will decrease.  That’s how batteries work.  So the less often you want to run your generator, the more electricity you’ll need the batteries to store.

If you get enough storage to power your cabin for a full 24 hours (17 kWh in this example) then you can get away with running your generator once per day for however long it takes to generate the needed 17 kWh.  However, if your batteries can only store 10 kWh, you’ll have to run your generator at least twice per day to recharge the batteries before they run out.

But remember, battery storage isn’t cheap.  So consider the trade-offs between purchasing more battery storage and having to run your generator two or three times per day.  Also consider some ways to reduce the noise from your generator around your cabin.

How much can your generator output

This doesn’t really impact the amount of battery storage you need.  But it does impact how long your generator will need to run in order to charge your batteries.

The generator I like for multi-purpose use, especially at the cabin is the Champion 76533.  I actually have an article about this generator and why I like it here.  I also give some alternatives if you want something with remote start, or something quieter.

This generator, for example, has a running output of 3800 watts.  If I have 17 kWh of storage, it’ll take me (17,000 Watt-hours divided by 3,800 Watts) about 4 1/2 hours per day to charge my battery system.  If I go with the bigger 7,000 Watt option for my generator, then it’ll take me just 2 1/2 hours per day.

By having a batter system large enough to run a generator once per day, I can just turn on the generator before going inside for dinner and let it run for the next couple hours while I’m inside and can’t hear it.  Then, I can go back outside a few hours later and turn it off.

If you go with less storage, you’ll save money but you’ll have to do that more often.

 Install the appropriate battery system

So now that you know how much storage you need or want, you need to figure out the best option.

There are lots of options when it comes to batteries, and there are a few things you need to keep in mind as you look at your options.

Depth of Discharge.  This is the amount of storage in the battery that you can actually use.  Believe it or not, a 10 kWh batter can’t actually always give you 10 kWh.  Some of a 90% DoD which means you can only use 9 kWh before you should recharge.  Some batteries, like the Tesla Powerwall which I’m excited to try, have a DoD of 100%.  Some other types don’t.

Round Trip Efficiency.  This is how efficient the batteries are.  Basically, a battery can’t give out 100% of what it takes in.  Some energy is lost in the process.  If a battery has 90% efficiency then a 10 kWh battery can still store 10 kWh for use, but it will take a little over 11 kWh from the generator to charge it all the way.

To find the right setup for your cabin and to make sure it’s set up properly, I recommend that you contact a local solar energy company.  They know how to set up home batteries since they’re used regularly in solar power systems.  They will be able to talk you through the battery options and their associated costs.

However, if you insist on doing it yourself, keep an eye out for future content from Cabin Freedom on the different battery options, where to get them, and how to set them up for use with a generator or with solar panels.

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