Experimental study on the effect of alternator speed to the car charging system

2.2 Experimental procedure 

The parameters of the experimental study are alternator speed (RPM), DC current value 

form alternator output (Amp), and battery voltage value (V). Three different speed of 

engine has been set constant, which are 750 RPM as idle speed, 1500 RPM and 3000 RPM 

as cruise speed. Car’s battery and alternator are being tested first before continuing with the 

experiment to make sure they are in good condition and fully functioning. A fully charged 

battery should read over 12.6 volts. The actual output voltage produced by the alternator 

will typically be about 1-1/2 to 2 volts higher than battery voltage. At idle, most charging 

systems will produce 13.8 to 14.3 volts with no lights or accessories on. 

Alternator speed

Current

Battery discharging

Charging

n

L

I

G

I

V

 

 

 

 

 

DOI: 10.1051/

,

(2017)

79001076

AiGEV 2016

90 

matecconf/201

MATEC Web of Conferences

01076 

5

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Fig. 6. Schematic diagram of experiment setup. 

Table 1 shows the electrical components in the car. The electrical components acted as 

load to the alternator. The electrical components were turned on one by one in sequences. 

These steps applied to all three different speed. The value of current at alternator output and 

battery voltage was taken after each time the electrical component was turned on. 

Table 1. Proton Preve electrical component. 

After all the available electrical components had been turned on, and the measurement 

has taken, all of the electrical components were turned off, and leave the car idle for five 

minutes. The speed remained constant. After five minutes, the battery voltage was 

measured again.  

Every time before switch to new alternator speed, the battery needed to be sure that it 

has fully charged. 

Alternator Output

AC/DC Clamp

Fuse Box

Alternator

Tachometer

Engine Belt

Car Engine

Battery

Multimeter

Timing Light

Continuous Loads