First – what voltage system do you have?
Let’s do the basic 24 volt or 48 volt system and standard off-grid lead-acid batteries at 6 volts to get started.
For a 24 volt system, you will need FOUR 6-volt batteries (4×6=24). To increase your power, you will need to increase your 6 volt batteries by FOUR each time so that they will be a multiple of 24. So, the first step is 4 batteries, the next 8, the next 12, and so on. There is a benefit to this in that you can start smaller and add on – however you don’t want to wait too long to add as your batteries will only be as good as your weakest one.
If you have a 48 volt system, you will need EIGHT 6-volt batteries (8×6=48). To increase your power, you will need to increase your 6 volt batteries by EIGHT each time, so they will be a multiple of 48. So, the first step is 8 batteries, followed by 16, and then 24, etc…
What are the different battery types and pros and cons of each?
As stated earlier, our favorite battery by far is the Nickle Iron. They can be discharged all the way down to zero and not hurt them, they can even be LEFT discharged and be ok years later. This is a huge benefit, however the cost is the highest of all the batteries. They are also no longer made in the USA – they need to be ordered from China, so availability is not guaranteed.
Lithium is an alright choice if you are not going to be leaving them unattended in the winter. They can be discharged up to 95% and can last about 15 years. They will have to be kept warm, so will be using some of your precious power for that. Not too much, though. They are the middle cost for batteries – but they are closer to the cost of Nickle Iron than the lower cost of Lead Acid.
Lead Acid is by far the least expensive option but they can only be discharged to 50% and they will last the least long of any. There is more upkeep with these as you have to check them for water every month or so. Although they say they last longer, the longest mine have lasted in my own home is 8 years – and I definitely noticed a reduction after about 5 years. I use them very hard. We are completely off-grid and do not skimp on using power.
One of your biggest decision is what type of battery you will choose and how many you will need to give you the power you want. We will be discussing this in detail as you plan and decide.