Off Grid Home Forums Technical Discussion How to set up Off the Grid or Emergency Battery Banks

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    Found this on FaceBook, looked like a lot of good info all together in one place

    How to set up Off the Grid or Emergency Battery Banks

    When planning to go off-grid the very most important knowledge you will require has to do with the battery bank set up that you will use. In this post we’ve laid out a massive amount of information concerning setting up a battery bank for your needs!

    For those who are looking for visual examples we’ve made a playlist on YouTube just for you! More technical information is provided below.

    Building a battery Bank
    Battery banks are the best choice for renewable energy storage. By using batteries to deliver energy captured from the sun and the wind in a consistent and reliable form, renewable power enthusiasts will not be left dependent on the whims of nature as they attempt to leave the electrical grid behind them.

    Grid Storage Batteries
    Renewable energy sources such as wind and sun do not provide a steady stream of power, nor do they harmonize with user demand. Large energy storage batteries called load leveling or grid storage batteries are needed to provide a seamless service.

    Battery Bank Configurations
    There are 2 main types of ways to connect your batteries together. One is putting your batteries in Series, this will double the voltage and leave the amp-hour rating the same. The other is connecting them in Parallel, which will double the amp-hour rating and leave the voltage the same. Depending on what voltage you need, what types of batteries you use and what amp-hour rating you need you will have to use one or both of these connection methods.

    How to Size a Battery Bank
    Battery bank sizing can be one of the more complex and important calculations in your system design. If the battery bank is oversized, you risk not being able to keep it fully charged; if the battery bank is sized too small, you won’t be able to run your intended loads for as long as you’d planned.

    Battery Types
    There are 3 main types of batteries you can get into today’s market for your Alternative Energy System. These 3 are AGM (Absorbed Glass Mat), Gel Cell(Sealed), and Flooded Lead Acid batteries.

    Calculating Battery Capacity
    Everyone wants a battery that is small and light, but there are compromises, especially if the margin for failure is narrow for critical missions. When calculating battery size, the fleet user should consider two factors: [1] allowing for spare capacity to provide for unforeseen activities, and [2] anticipating capacity fade that occurs naturally with the age of the battery. Equipment manufacturers tend to ignore the fading aspect when calculating the required capacity and base the service on a new battery with full capacity.

    The acceptable capacity performance range of a well-managed battery fleet is 80 to 100 percent, meaning that packs that fall below the 80 percent threshold are replaced. Allocating 20 percent fade in addition to a 20 percent emergency reserve would reduce the usable battery capacity to 60 percent. Such a large reserve for a worst-case scenario may not be practical and battery users go for more leniency. A battery analyzer plays an important role in battery management in that the batteries are checked every one to thee months to ensure they all fall within the anticipated performance bandwidth.

    Testing Batteries
    Testing is designed to tell us things we want to know about individual cells and batteries.
    Some typical questions are:
    Is it fully charged ?
    How much charge is left in the battery ?
    Does it meet the manufacturer’s specification ?
    Has there been any deterioration in performance since it was new ?
    How long will it last ?
    Do the safety devices all work ?
    Does it generate interference or electrical noise ?
    Is it affected by interference or electrical noise ?
    The answers are not always straightforward.

    Information taken from:

    Battery University

    Alt Wind Power

    Btek Renewable Energy

    Off The Grid News

    I haven’t looked through these, as with anything else, please proceed with caution and common sense.

    Jennifer Kelly

    That’s a real wealth of information.  Love it!


    Do you currently use battery banks?  What have you found to be the best solution?


    Yes, I have batteries on my solar system, we are not grid tied. Speaking of batteries, will have to add more detail in a day or two, it’s been overcast all day (rainy, we need it!) and is supposed to be this way for a few days, so no sun means little to no charging…


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