size of lithium battery bank - 3.2v cells

Discussion in 'Electrical Systems' started by jdory, Oct 4, 2018.

  1. M&M Ovenden
    Joined: Jan 2006
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    M&M Ovenden Senior Member

    While the term "load" is fairly vague, it's implied that it is an element in a circuit that consumes energy, the source supplies the energy. A load can be resistive, capacitive, inductive or a combination of them all. As I've show with above examples a load can draw constant power from a battery (constant power load) - I was pointing this out about your comment: "As the battery discharges, the voltage goes down. Therefore, the power output also goes down." is not always true.

    Most loads these days have switching regulators on the front end. This doesn't apply to motors - but they are fairly tolerant of input voltage.

    I did not quantify DoD, I have only noted that I am happy to follow industry standard definitions. I understand these have various limits and I find it is possible to work within this framework.
    I thought you agreed with them also by the above comment.

    I think that wraps this up.

    Cheers,
    Mark
     
  2. gonzo
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    gonzo Senior Member

    The term "load" is not vague, but formally defined as "any component of a circuit that consumes power or energy". Also, switching regulators usually generate a very dirty power supply. It is possible to clean it, but at the expense of efficiency.
     
  3. M&M Ovenden
    Joined: Jan 2006
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    M&M Ovenden Senior Member

    We use switching regulators because of their efficiency over a linear regulators. For sensitive electronics there is power conditioning required, but it's negligible in the overall power budget.
    Posting comments that are misleading are not helpful to other forum members.
     
    Ad Hoc and rxcomposite like this.
  4. rxcomposite
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    rxcomposite Senior Member

    Agree. And here is the comparison.
    >Linear Regulators
    Linear regulators are a great choice for powering very low powered devices or applications where the difference between the input and output is small. Even though they are easy to use, simple and cheap, a linear regulator is normally inefficient.

    The equation for dissipated power in a linear regulator is:
    Power dissipation = (input voltage – output voltage) × load current

    Switching Regulators
    Switching regulators on the other hand are highly efficient and available as modular chips which are compact and reliable. Switching regulators can be further divided into isolated and non-isolated.< https://www.renesas.com/sg/en/products/power-management/linear-vs-switching-regulators.html

    Noisy, yes but enclosing it in a metal enclosure solves it. Expensive to make due to parts count? Not if you produce in volume.

    Almost all PC and low power electronic devices use switching regulator power supplies.
     

  5. gonzo
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    gonzo Senior Member

    They are not expensive for low power applications. However, if the whole electrical system is regulated, large loads like starters, windlasses, searchlights, etc. will require a huge regulator which is expensive. It is also unnecessary unless you are trying to win an argument. Further, the discussion's focus is on quantifying DoD. It is irrelevant whether the voltage is regulated or not. Since you request using industry standards, then discharge to 10V is considered.
     
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