When you're doing any kind of modding to your vehicle, always calculate a head of time how much power (in watts) will the component(s) you're mounting into your vehicle consumes, on top of your stand power consumption from the existing electrical components. Examples of your existing electrical components are your engine moving parts that require power (such as the gasoline pump, cooling fan, sensor circuits, etc..), your stereo cd/radio, lights, seat heater, and others. Make sure you calculate, recalculate, and ensure that the remaining electrical usages (or known as electrical loads) can support the component(s) you're installing.

Before you start counting the electrical usages, make sure you keep in mind that not all of the equipments are turned on at one time. The mechanical sensor arrays, the fuel pump components, the power steering pump, ABS, illumination, well, those are required. A/C, heater, blower/fan, radio, those are optional, so you can count them in if you like.

The average 2001-2002 Santa Fe has a 95A alternator/generator. 95A at and average of 14.2V production output during driving at 20mph, and at 13.8V at idling. The equation:

P=IxV
• P = Power in Watts
• I = Current in Amps
• V = Direct Current Voltage produced by the alternator

  Here's a convenience automated calculator for you to use:

  OHM’S LAW CALCULATOR

  Side Note: OHMS = Resistance, in Ohms (normally use in small resistors and regulators for reducting high voltage to lower voltage)

  Enter any TWO known values then you'll get the unknowns. Press the calculate button after you have made your entries:

  
  

  VOLTS

  AMPS

  OHMS

  WATTS

  
  
  

Below is an existing list of electrical usages, not a complete one, that your stand Hyundai vehicle normally use. Start add them up.

LIGHTING SYSTEM
ITEMS	BULB WATTAGE (W)
Head lamp	60W / 55W (High / Low)
Front turn signal lamp	28W
Front position lamp	8W
Front fog lamp	55W
Side marker lamp	5W
License plate lamp	5W
Luggage lamp	10W
Room lamp	10W
Map lamp	10W
High mounted stop lamp	17W
Door courtesy lamp	5W
Rear combination lamps:
Tail/stop lamp	8W / 27W
Back up lamp	27W
Turn signal lamp	27W
TOTAL MAXED POWER USED AT ONE TIME	375 Watts

MECHANICAL PARTS
Part Type	SPECIFICATION	POWER USAGE
Wiper Motor (no/light rain) Remember there are 2 (front and rear)	Low : 39-47 rpm/4.0A or less High : 60-74 rpm/6.0A or less	48 Watts or less 72 Watts or less
Wiper Motor (heavy rain) Remember there are 2 (front and rear)	Low : 34-42 rpm/7.0A or less High : 46-58 rpm/9.0A or less	84 Watts or less 108 Watts or less
Windshield washer There are 2	During usage: 5A or less	60 watts or less
Air Conditioner Sensor (A/C is driven by the engine's belt)	Max usage: 5A at 12V	60 Watts
EVAP Canister Purge Solenoid Valve	0.45A	5.4
Fuel Pump	0.5V (idle) to 4.8V (max RPM) at 25A	12.5W to 125W
Sensor Arrays	25A at 5V max	125W
Power Steering Oil Pump	20A at 5V max	100W
Cabin Heater Unit	25A at 12V (with sensor uses 5A)	360W
Cabin Blower/Fan	20A at 12V	240W
TOTAL MAXED POWER USED AT ONE TIME		1387.4 Watts

INSTRUMENTS AND WARNING SYSTEM
Warning lamps	Bulb wattage (W)
Illumination	3.4
High beam	1.4
Low fuel	1.4
Turn signal (LH, RH)	1.4
Battery (charge)	1.4
Oil pressure	1.4
Air bag	1.4
Parking brake	1.4
Seat belt	1.4
Check engine	1.4
ABS	1.4
Door ajar	1.4
Tailgate open	1.4
Cruise	1.4
TCS	1.4
Automatic Transmission Gear Display
Park (P)	1.4
Reverse (R)	1.4
Neutral (N)	1.4
Drive (D)	1.4
4th Gear (4)	1.4
3rd Gear (3)	1.4
2nd Gear (2)	1.4
1st Gear (1)	1.4
Digital Clock	2.5
TOTAL MAXED POWER USAGE AT ONE TIME	36.7 Watts

Let see...My SUV normally use the mechanical components:

• 355 Watts

• 36.7 Watts

• 375 Watts

So I still have 582.3 Watts to play with my toys. If I turn on the A/C, blowers, etc..hm...Say bye bye to all the existing juice I have for my toys. So, secondary auxillary battery should be installed!

Now, for those who are concerned about your vehicle eating more gasoline because you use all of the electrical loads, that's merely a myth. What ever your alternator/generator can provide, that's how much juice you can use. If your electrical load goes beyond what the alternator can provide, two things will likely to occur:

1. You drain your battery, until your battery runs out of juice, or to the point where the voltage is too low to support your vehicle's electrical function. At this time, your vehicle should be either sputtering, or stopping due to the lack of power for your ignition system.
2. Your alternator/generator is going on a meltdown stage, since you're overloading your electrical usage. Your wires and wire harnesses will probably melt away as well...But the chance of the wires and alternator/generator undergo a meltdown stage is very unlikely.