Battery basics for electronics

Batteries are used in portable devices and for backup energy storage.

Learn all you can about the particular batteries you are interested in using by doing a google search, reading books, etc. This is just a quick introduction to battery basics and only covers the most commonly used battery types.

Quick list of general battery topics:

  • Short circuit danger. Never connect positive terminal directly to the negative terminal. Always have a load between them that limits the power to a safe level for both the load and the battery.
  • Positive terminal (Cathode). Never connect directly to the negative terminal of the same battery.
  • Negative terminal (Anode). Never connect directly to the positive terminal of the same battery.
  • Cell chemistry.
  • Voltage.
    • Nominal voltage. Approximate average voltage that you can expect from a cell or battery made up of series of cells when you use it from fully charged to fully discharged.
    • Fully charged: Cell/Battery will be at it’s highest safe voltage, and will be able to provide the most power.
    • Fully discharged: Cell/Battery voltage is low and won’t be able to provide much power. It will be more dangerous to recharge a lithium based battery if it is over discharged.
  • Current.
  • Primary battery. Simply a battery that is not rechargeable.
  • Secondary battery. Simply a battery that is rechargeable.
  • Series connected cells for increased voltage. Connecting the positive terminal of one battery to the negative terminal of a different battery. Can keep stacking multiple batteries like that as long as the 2 ends of the series batteries never come in direct contact with each other (a short circuit). Only use cells/batteries of the same chemistry, that are at the same voltage, and that have the same capacitance.
  • Parallel cells for more current over time. Make sure they are equally charged (no more than 0.1V difference) while connecting them together or one will rapidly charge the other.
  • Capacity
    • Ampere hour, amp hour, AH.
  • C rate.

Cell chemistry:

Knowing the cell chemistry is important for a number of reasons.

  • Rechargeable or not. And how to recharge if rechargeable.
  • Maximum and minimum safe voltages.
  • Energy density.

Common chemistries:

  • Alkaline:
  • LiFePO4 (lithium Iron Phosphate):
  • Li Ion (Lithium Ion):
  • Lead Acid:

Alkaline batteries:

Disposable batteries (recycle them when they die). Mostly used in portable devices that aren’t rechargeable.

LiFePO 4 (Lithium Iron Phosphate) batteries:

Rechargeable batteries. Commonly used for backup power for households and RVs. Less likely to combust than li ion and LiFePO4 chemistries.

Li ion (Lithium Ion) batteries:

Rechargeable batteries. Typically used to in lower power rechargeable devices that have a USB charging port.

Lead Acid:

Rechargeable battery that is commonly used to start internal combustion automobiles.

LiPo (Lithium Polymer):

Rechargeable battery that is commonly used to power devices that need a lot of power from a lighter weight battery, such as flying drones.

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