# How Many Load Resistors Do I Need?

## Do I need a relay for LED lights?

A relay is an electrical switch that lets a low current circuit control a high current circuit such as a large LED light bar.

If you are using a light pod that does not have a very large amp draw, you may not need a relay switch, but if you are using a larger LED light bar, they are a must have..

## Does it matter if the resistor is before or after the LED?

It doesn’t matter! The resistor can go before – or after – the LED, and it will still protect it. You see.. the current that flows out of a battery is always equal to the current that flows back in to the battery. … The current through the resistor is the same as the current through the LED.

## What happens when an LED is directly connected to a power supply?

When LED is connected to a power supply with a voltage higher than its forward voltage, a current limiting resistor is connected in series with the LED. The current limiting resistor limits the current for the LED and regulates the difference in voltage drops between the LED and the power supply.

## Can a bus resistor terminate?

A CAN Bus network must have a terminating resistor between CAN High and CAN Low for it to work correctly. For maximum range over long distances, the ideal termination is one 120 Ohm resistor at each end of the bus, but this is not critical over short distances.

## Do LED turn signals need a load resistor?

Yes, you will need a load resistor for each LED bulb you install on a turn signal circuit.

## How many LEDs can a 12v battery power?

The answer should be the source voltage divided by the voltage drop of 1 LED. So if your source is 12v, and your LEDs have a voltage drop of 3.5, 12/3.5v, gives you 3 LEDs. If the the forward voltage drop of the LEDs was exactly 3 volts, you’d be able to drive 4 of them, and would not need a current limiting resistor.

## What resistor do I need for LED indicators?

Basics: Picking Resistors for LEDsPower Supply VoltageLED ColorResistor (calculated)5 VRed, Yellow, or Yellow-Green128 Ω5 VRed, Yellow, or Yellow-Green56 Ω9 VRed, Yellow, or Yellow-Green72 Ω9 VBlue, Green, White, or UV96 Ω4 more rows•Aug 29, 2012

## What happens if you don’t use a resistor with an LED?

If you don’t put a resistor in series with the LED and you apply power, the current through the LED will exceed its rating and it will be destroyed. You can use the following equation to solve for R. Vdiode is the diode’s forward turn on voltage.

## Do I need a resistor for each LED?

This means 30mA through the current-limiting resistor will be divided into 15mA for each LED. However if one LED has a higher CHARACTERISTIC VOLTAGE-DROP, it will take less current and the other LED will take considerably more. Thus you have no way to determine the “current-sharing” in a string of parallel LEDs.

## What does a load resistor do?

At the most basic level, load resistance is the cumulative resistance of a circuit, as seen by the voltage, current, or power source driving that circuit. … A load resistor is a resistor that has the sole function of increasing the load resistance of the circuit to a specific level.

## Do LED load resistors get hot?

The load resistor is holding back power and the result of holding that power back so it does not get to the LED lights is heat. … Much like a light bulb the resistor is going to become warm or hot to the point of being uncomfortable to touch.

## Is led Hyper Flash bad?

If you’re asking if it hurts the electrical system, probably not. – It may wear out the flasher faster than it would have, which is still probably never. – It will make it look like you have a blinker burned out, but as long as you don’t, I can’t imagine that hyperflash in and of itself is illegal.

Resistors used in this manner, however, are an inefficient use of energy. They do not perform any physical action and can overheat and melt insulation, causing short circuits and possible fire hazards. As the size of the load resistor matches the replaced globe, there is no saving in energy.

## Can I connect a LED directly to a battery?

Powering an LED is not as easy as simply hooking it up to a battery. An LED has almost no internal resistance. Therefore, if you hook it up directly to a battery, it will burn out quickly as the current flows unimpeded through the LED. You must add a resistor to the LED circuit.

## Do resistors waste power?

But the energy dissipated by a resistor used in a circuit is almost always “wasted” energy in a sense. A resistor turns valuable electrical energy into heat. Unless this heat is used productively (in a baseboard heater, for example) that heat is normally considered wasted.

## How many LEDs can be connected in parallel?

Wiring LEDs in parallel allows many LEDs to share just one low voltage power supply. We could take those same four 3V LEDs and wire them in parallel to a smaller power supply, say two AA batteries putting out a total of 3V and each of the LEDs would get the 3V they need.