In the previous Part 1, we made an overview the batteries from their historical basics.
The Batteries – PART 2: Uncovering
We will separate the batteries in two categories:
- Primary or Disposable Batteries;
- Secondary or Rechargeable Batteries.
Today we will discuss to the first category:
The Disposable batteries.
The common way to create their construction is using the metallic body – connected to the negative battery terminal, and encapsulated the second battery terminal, connected the positive pole – battery central electrode.
PIC. 1 Zinc/Carbon Dry Cell
But, there are some exceptions – The button looking lithium battery with EFM=1.5V or EFM=3V has the positive Battery terminal connected to the outside metallic Body. The smaller encapsulated terminal is connected to the negative battery inner port.
Inside the body, there is the electrolyte and the electrodes – isolated by a perforated separator.
PIC. 2 The Button Battery – Uncovering
Here can see the button batteries variety – You can check the dimensions, numbering, EMF – U nominal Voltage, and their approximate capacity [mA/h].
Link to: Watch Batteries – External Link.
Link to: VARTA Lithium Battery Catalog – in PDF format.
The batteries are a kind of electrochemical cells. They can convert a chemical energy to electrical energy (and back to a chemical energy in the rechargeable cells, during the charging process), using only two separated electrodes, connected together only via an electrolyte.
The Disposable batteries.
They can be used only until their voltage is acceptable – it means for only one full discharge cycle:
The whole Disposable battery live stays between these two limits: EMF =~ 1.5 V to their fully discharged state: EMF = ~ 0V .
The Useful low limit in the practice for a single cell dry battery is near EMF = 0.9 – 1V. The battery’s internal resistance, which became too high, doesn’t allow the battery to deliver a significant current to the load.
- Conventional current flow: The current flow direction seen with the conventional measuring tools, e.g. the multimeters. It is the direction in which, the positive electronic charges are moving.
- Electrons movement direction – the negative :
- Cathode: This terminal can take Negative or positive polarity with respect to the anode – depending on the device (Battery or Load) kind of operation – Discharge or charge.
If the Device generates energy, e.g. it is Power Source, it’s Cathode electrode has the Positive polarity;
If the Device consumes energy, e.g. it is a Load, it’s Cathode electrode has the Negative polarity;
- Anode: opposite Polarity on the Cathode terminal.
You can make an association: the current’s directions and the electrodes names are the same as in the Zinc/Carbon dry cell.
The illustration above shows the Zn/Cu daniel’s cell – not to mistake with the regular Zinc/Carbon dry elements.
The Charging process of disposable Zink Cells doesn’t have a practical value – we use a picture only with the educational goal – to be seen the current directions and the name of the electrodes.
Structure of a Zinc / Carbon Dry Cell Element:
Main Battery Characteristics:
- Primary or Disposable Battery
- Secondary or Rechargeable Battery
- 1.2V Ni-Cd, 1.36 Ni-MH, 1.5V Zinc/Carbon, 1.55V Alkaline Dry Cell, 2V Lead Acid Cell, 3V- Lithium Battery Cell, 3.2-3.3V LiFePO4, 3.7V Li-Ion.
- Capacity: The theoretical battery capacity is given by the electricity’s quantity involved in the electrochemical process.
- Discharge or Load curve: The desired theoretical curve must be the straight, near the horizontal line, but on the practice, the Load curve has the character of the curves shown the diagram below.
- Temperature dependence:
Don’t Stop To Reinvent Yourself, Dear Explorers!
To be continued!
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