1 / 22

Motorcycle Electrics - PowerPoint PPT Presentation

Motorcycle Electrics. By Jerry Skene. Overview of Seminar. Volts, Amps, Watts & Ohms What they measure and how they are used (includes Ohm’s law) Batteries & charging Adding lights and other accessories Common tools & supplies. Volts.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

PowerPoint Slideshow about 'Motorcycle Electrics' - kimball

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Motorcycle Electrics

By

Jerry Skene

• Volts, Amps, Watts & Ohms

• What they measure and how they are used (includes Ohm’s law)

• Batteries & charging

• Adding lights and other accessories

• Common tools & supplies

• Measure of the electric potential between two conductors, or the ability to move an electric charge through a resistance

• Motorcycles use a 12V DC (direct current) system

• Measured with a voltmeter

• ignition-off voltage is ~ 11.9 volts

• operating voltage is ~13.8 volts

(lowest lethal voltage is ~ 60 volts)

• Measure of current flow through a circuit

• Headlight bulb draws ~ 4.5A

• Tail light bulb draws ~ 0.4A, or 400 milliAmps (mA)

• Electrical symbol for current is I

Minimum lethal current through the

human body is 80 – 100 mA

• Watt is a unit of electrical power (P)

• Corresponds to the power developed in a circuit by a current of one ampere flowing through a potential difference of one volt: Power = Volts x Current (I)

• a headlight connected to 12V Volts, drawing 5 Amps consumes 12 x 5 = 60 Watts

• BMW motorcycle alternators provide the following electrical power:/5 180W R90s 238W1000cc to `80 250W recent R/K bikes 400 – 600 WK bikes (pre-2005) 700WK LT 840W

Ohms (Ω)

• A Ohm (Ω) is a unit of electrical resistance

• An ohm is the resistance that produces a potential difference of one volt when a current of one ampere is flowing through it.

• A typical 60W high beam bulb has a resistance of 0.4 Ω.

• 5’ of 18Ga wire has a resistance of 0.03 Ω.

• Very useful law relating voltage, current and resistance

• States that Voltage (V) across a circuit is equal to the current (I) times the resistance (R): V= IR or I=V/R or R=V/I

• So… the voltage drop across a 5’ length of 18Ga wire (R=0.03Ω) carrying 5A of current is…. V=0.03 x 5 = 0.15V

• Use Ohm’s law to calculate the size of fuse needed to power an 80 watt heated vest:P = 80W V = 12V (P=V x I), so I = P/Vor 80/12 = 6.6 Amps (next larger common fuse size is 7.5A)

• Measured in mm2or gauge # American Wire Gauge)

• Can use resistance table to determine total resistance of added wiring

Cross-sectional area Overload Typical Use current rating

0.5 mm² (20 AWG) 3 A instr., turn signals

0.75 mm² (18 AWG) 6 A headlight

1 mm² (17 AWG) 10 A h/l ground

6 mm² (10 AWG) 30 A battery

• Motorcycle batteries are of the Lead Acid design

• There are several variations of Lead Acid:

• Wet Cell (flooded):serviceable, and maintenance free

• Gel Cell

• Absorbed Glass Mat (AGM)

• Gel and AGM require less service than flooded Lead Acid

• Gel Cell and some AGM batteries may require a lower charging rate

• your motorcycle’s charging system usually dictates the type of battery you require

• Gel cells have a lower recharge voltage, and can be damaged by too high a charge rate – best to use a Gel charger

• A fully charged battery should read 12.8-12.9 V

• Sulfation occurs when the voltage drops below 12.4 V

• Most premature battery failures are caused by sulfation buildup – a result of losing charge

• Buy a trickle or smart charger, and use it frequently.

• Common causes of premature failure:

• Battery sits too long between charges. As little as 24 hours in hot weather and several days in cooler weather.

• Battery is stored without some type of energy input (self discharge).

• "Deep cycling" an engine starting battery. Remember these batteries can't stand deep discharge.

• Undercharging of a battery: charging a battery to 90% of capacity will allow the 10% of battery chemistry not reactivated to sulfate the battery

• Heat of 100º F increases internal discharge. As temperatures increase so does internal discharge. A new fully charged battery left sitting 24 hours a day at 110º F for 30 days would most likely not start an engine.

• Low electrolyte level - battery plates exposed to air will immediately sulfate.

• Incorrect charging levels and settings. Most cheap battery chargers can do more harm than good. See the section on battery charging.

• Cold weather is also hard on the battery. The chemistry does not make the same amount of energy as a warm battery. A deeply discharged battery can freeze solid in sub zero weather.

• Parasitic drain is a load put on a battery with the key off. This can drain a battery in a few days

• The most common addition is driving or fog lights

• Wire these directly to the battery through a fuse and relay

• Recent BMW’s monitor brake light current

• LED’s take much less current: 0.2A vs ~2A

• You must wire a resistor in parallel with the LED light to fool the computer into thinking you have a stock brake light

• Ohm’s law says R=V/I = 12/2 = 6Ω, can use 8Ω

• Remember P = V X I, so P = 12 x 1.5 = 18 watts, so you need a 20W power resistor

• Even a small decrease in voltage to your headlight can dramatically reduce its light output:

Voltage Output

10.5V : 510 lumens11.0V : 597 lumens11.5V : 695 lumens12.0V : 803 lumens12.5V : 923 lumens12.8V : 1000 lumens ←Rated output voltage13.0V : 1054 lumens13.5V : 1198 lumens14.0V : 1356 lumens ←Rated life voltage14.5V : 1528 lumens

• Consider running heavier wires in parallel with your existing headlight wiring to minimize voltage drop.

• BMW uses 0.75mm2 (18ga) wire for headlights, causing ~1.2V drop in voltage

• Adding 12 ga wire in parallel to this will provide a significant increase in brightness.

• Wire cutters

• Long-nose pliers

• Wire strippers

• Get a Digital Multimeter

• < \$8 at Allelectronics.com

• Good crimp tool is an excellent investment

• (try Starkelectronics.com)

• Soldering iron or soldering gun for heavy gauge wire

• Tap connectors are common: be sure to use the correct size for the size of wire – too small can damage original wire, too large will not make a reliable connection

• Heat-shrink tubing and a heat-gun will help make weatherproof connections

? ? ?? Questions ? ? ? ?