Changes between Version 8 and Version 9 of ElectricalIntroduction

Timestamp:

Aug 21, 2017, 10:57:43 AM (8 years ago)

Author:

David Albert

Comment:

--

ElectricalIntroduction

@@ -13 +13 @@
 * Primary: disposable batteries that you throw away when their chemicals have fully reacted and can't make electrons flow anymore (battery is fully discharged)
 * Secondary: rechargeable batteries where if you force current to flow through the battery in the reverse direction after the battery is discharged, the chemical reactions reverse themselves (the battery is re-charged) so it can make electricity flow again.
-Common commercial batteries include different chemical compositions: carbon-zinc, alkaline, lithium, lead-acid, etc. and different sizes including: [https://en.wikipedia.org/wiki/AA_battery AA/penlight], [https://en.wikipedia.org/wiki/D_battery D/flashlight], [https://en.wikipedia.org/wiki/Nine-volt_battery 9V/radio], [https://en.wikipedia.org/wiki/Lantern_battery 6V/lantern], and a wide range of custom sizes.  Batteries vary widely in size, capacity, and characteristics.  In general, the larger the battery, the more chemicals it contains and the more electrical energy it can generate through the chemical reactions. The chemistry and construction determine whether the battery is disposable or rechargeable.
+Common commercial batteries include different chemical compositions: carbon-zinc, alkaline, lithium, [https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery lead-acid], etc. and different sizes including: [https://en.wikipedia.org/wiki/AA_battery AA/penlight], [https://en.wikipedia.org/wiki/D_battery D/flashlight], [https://en.wikipedia.org/wiki/Nine-volt_battery 9V/radio], [https://en.wikipedia.org/wiki/Lantern_battery 6V/lantern], and a wide range of custom sizes.  Batteries vary widely in size, capacity, and characteristics.  In general, the larger the battery, the more chemicals it contains and the more electrical energy it can generate through the chemical reactions. The chemistry and construction determine whether the battery is disposable or rechargeable.
 
 FRC competition robots use large re-chargeable [http://www.andymark.com/power-patrol-sla1116-12-volt-18ah-batteries-2-pack-p/am-3062.htm lead-acid batteries].  Team 2537 also uses [http://www.batterysharks.com/12-Volt-7-Amp-Sealed-Lead-Acid-Battery-p/12V-7AH_B12-7.htm smaller lead-acid batteries] to power lighter duty robots like peanut bots.  All of these batteries are sealed so the acid/electrolyte doesn't get out and are called Sealed Lead Acid (or SLA) batteries; they also store a lot of energy and should be treated with respect.
 
+For more information and details on batteries, see [http://www.edu.pe.ca/gray/class_pages/krcutcliffe/physics521/22current/applets/Electrical%20energy%20and%20electrical%20potential.htm here] and [http://www.mpoweruk.com/chemistries.htm here].
+
 
 === Voltage === 
-The difference in electrical potential between the two terminals is measured in units of Volts (named after [https://en.wikipedia.org/wiki/Alessandro_Volta Alessandro Volta]).  Voltage is *potential* energy, like the reservoir/lake behind a hydroelectric dam; no work is being done if the water isn't flowing, but you can measure the pressure the water is exerting on the dam.  Voltage is a potential, it represents a difference in charge, the strength of attraction between two opposite charges.  Different types of batteries use different types of chemical reactions to generate that charge potential difference.  The oldest type of battery, and the one we still use on our robots, is the [https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery lead-acid] battery which uses lead terminals and sulphuric acid.  
+The difference in electrical potential between the two terminals of a battery is measured in units of Volts (named after [https://en.wikipedia.org/wiki/Alessandro_Volta Alessandro Volta]).  Voltage is *potential* energy, like the reservoir/lake behind a hydroelectric dam; no work is being done if the water isn't flowing, but you can measure the pressure the water is exerting on the dam.  [[Image(dam_diagram.png,right,20%,nolink)]] Voltage is a potential, it represents a difference in charge, the strength of attraction between two opposite charges.  Different types of batteries use different types of chemical reactions to generate that charge potential difference.  For more information about electricity and voltage, see [https://learn.sparkfun.com/tutorials/what-is-electricity here]  
 
-You can use a meter called a voltmeter or a multimeter to measure the amount of voltage "pressure" a battery exerts. 
+Different [http://www.houseofbatteries.com/battery-chemistry-chart-i-52-l-en.html battery chemistries] generate different voltage potentials.  For example, NiMH rechargeable batteries create about 1.2 volts, alkaline disposable batteries create about 1.5 volts, lead-acid rechargeable batteries create about 2 volts, and lithium batteries create 3-3.7 volts.  You can connect batteries in sequence to increase the difference in charge (voltage) between the battery terminal at the start of the sequence and the battery terminal at the end; this is called placing the batteries in ''series''.  By placing 6 lead-acid cells in series you can make a 12V battery (which is what we use for robots).  When you buy a 12v SLA battery, it really contains 6 individual 2V cells in one package.  The lead-acid battery is the oldest type of battery, and is the one we still use on our robots, lead-acid batteries have lead terminals and sulphuric acid electrolyte.  
+
+You can use a meter called a voltmeter or a [multimeter to measure the amount of voltage "pressure" a battery exerts.  Multimeters are inexpensive ($5-25) and incredibly useful; every house should have at least one.  To learn how to use a multimeter, see [https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter this tutorial]
 
 [[Image(UT136B.jpg,left,20%,nolink)]] [[Image(Cen-Tech_Multimeter.jpg,20%,nolink)]]