If you're wondering how to calculate voltage drop, here is the voltage drop formula you should consider.
VD = I × R
Where,
VD is the voltage drop across an electric circuit component
R is the resistance in the circuit measured in ohms
I is the electric current determined in amperes (A)
For example, if a current of around 10 amps flows through the circuit and the resistance in the circuit is 30 ohms, the voltage drop will be 10A × 30 Ω = 300 V.
The concept of voltage drop describes the differences between the voltage supplied at the source and load.
Jackery Portable Power Stations are compact and lightweight charging solutions that can charge most household or outdoor appliances relatively long. They have higher capacities and operate at stable voltage, making them ideal for various scenarios.
What Is Voltage Drop?
The voltage drop across a load or conductor is equal to the product of current and resistance. While the resistance is measured by the conductor's physical properties, the circuit's load determines the electric current. There are many factors that determine the voltage drop:
|
Voltage Drop Factors |
Definition |
|
Conductor Material
|
Some materials are better conductors than others. Copper generally has more conductivity than aluminum. |
|
Conductor Diameter
|
Generally, a wider conductor has high conductivity as more material can carry electric current. |
|
Conductor Temperature |
Temperature also influences the material's conductivity. However, the conductivity will depend on the material and actual temperature. If the temperature increases, the conductivity may increase or decrease. |
|
Conductor Length
|
Generally speaking, longer conductors have high resistance because the current travels a longer distance between the source and load. |
|
Current Carried by the Conductor
|
According to Ohm's Law, the current is proportional to the voltage drop. That means the voltage drop will also be doubled if the current is doubled with the same resistance. |
|
Circuit Connections
|
The circuit connection represents the interruption in the conductor material and is also associated with contact resistance. The deficient connections experience an increased voltage drop. |
How to Calculate Voltage Drop?
The voltage drop formula will change depending on the number of phases on the circuit. Ohm's Law is the basic law for calculating voltage drops.
Here's how to calculate the voltage drop across a resistor using the voltage drop formula:
VD = I × R
Where,
I = Current through the wire (measured in amperes)
R = Resistance of the wire (measured in ohms)
For a single phase or direct current circuit, the voltage drop can be quickly determined using the below formula:
VD = (2 × I × R × L) ÷ 1000
Where,
I = Current through the wire
R = Resistance of the wire based on the length
L = One-way length of the wire
Let's take an example to understand:
If the single-phase 120V circuit carries around 10A current and the conductor impedance is 1.2 ohms per 1000 feet, the voltage drop in the 50 feet circuit length will be:
Voltage Drop = (2 × 10A × 1.2Ω × 50 feet) ÷ 1000 = 1.2V.
For a three-phase circuit, the voltage drop can be calculated as:
VD = (√3 × I × R × L) ÷ 1000
If the three-phase 120V circuit carries around 10A current and the conductor impedance is 1.2 ohms per 1000 feet, the voltage drop in the 50 feet circuit length will be:
Voltage Drop = (√3 × 10A × 1.2Ω × 50 feet) ÷ 1000 = 0.042V.
Where,
I = Current through the wire
R = Resistance of the wire based on the length
L = One-way length of the wire
If there are more conductors per phase, the formula must be divided by the number of conductors per phase because the resistance is reduced. For example, the resistance is reduced by half if there are three conductors per phase.
Note: The single-phase and three-phase circuit formulas are divided by 1000 because the standard impedance values are provided for every 1000 feet.
How to Select Wire Size to Avoid Voltage Drop?
Voltage drop is not something you talk about every day, but it is essential to understand if you are designing an electric system. The proper wire size and length will ensure the application's proper functioning and safety.
The simple method to avoid voltage drop is to choose a wire that is larger in diameter and has lower resistance. The American Wire Gauge (AWG) is a wire gauge system used in North America for the diameters of round, solid, electrically conducting, non-ferrous wire.
Choosing the correct wire size will depend on multiple factors, like the circuit's current and the wire run's length. Here are the steps to follow to select the correct wire size:
Determine Current Draw: You will first need to calculate the total current (in amperes) that will flow through the electric circuit.
Consult Wire Size Chart: Next, you will need to check the wire size chart to find the wire size based on the current and length of the wire run.
Consider Voltage Drop: You need to evaluate the acceptable voltage drop for the circuit. It should be within acceptable limits to maintain performance.
Select Wire Size: Finally, you need to choose a wire size that meets the voltage drop requirements for the circuit and the current carrying capacity.
The material is also an essential factor in reducing the voltage drop. For example, copper is a better conductor than aluminum and offers a lower voltage drop regardless of the length and wire size.
If you want to select the wire size, you need to multiply distance, current, and one over the number of conductors per phase. You can then divide permissible volt loss multiplied by 1,000,000. Finally, select the number from the table that is nearest but not greater than the obtained number. This will indicate the size of the wire needed.
Here is a list of typical AWG wires and their sizes:
|
AWG |
Diameter |
Turns of wire |
Area |
Copper resistance |
||||
|
inch |
mm |
per inch |
per cm |
kcmil |
mm2 |
Ω/km |
Ω/1000ft |
|
|
1 |
0.2893 |
7.348 |
3.46 |
1.36 |
83.7 |
42.4 |
0.4066 |
0.1239 |
|
2 |
0.2576 |
6.544 |
3.88 |
1.53 |
66.4 |
33.6 |
0.5127 |
0.1563 |
|
3 |
0.2294 |
5.827 |
4.36 |
1.72 |
52.6 |
26.7 |
0.6465 |
0.1970 |
|
4 |
0.2043 |
5.189 |
4.89 |
1.93 |
41.7 |
21.2 |
0.8152 |
0.2485 |
|
5 |
0.1819 |
4.621 |
5.50 |
2.16 |
33.1 |
16.8 |
1.028 |
0.3133 |
|
6 |
0.1620 |
4.115 |
6.17 |
2.43 |
26.3 |
13.3 |
1.296 |
0.3951 |
|
7 |
0.1443 |
3.665 |
6.93 |
2.73 |
20.8 |
10.5 |
1.634 |
0.4982 |
|
8 |
0.1285 |
3.264 |
7.78 |
3.06 |
16.5 |
8.37 |
2.061 |
0.6282 |
|
9 |
0.1144 |
2.906 |
8.74 |
3.44 |
13.1 |
6.63 |
2.599 |
0.7921 |
|
10 |
0.1019 |
2.588 |
9.81 |
3.86 |
10.4 |
5.26 |
3.277 |
0.9989 |
|
11 |
0.0907 |
2.305 |
11.0 |
4.34 |
8.23 |
4.17 |
4.132 |
1.260 |
|
12 |
0.0808 |
2.053 |
12.4 |
4.87 |
6.53 |
3.31 |
5.211 |
1.588 |
|
13 |
0.0720 |
1.828 |
13.9 |
5.47 |
5.18 |
2.62 |
6.571 |
2.003 |
|
14 |
0.0641 |
1.628 |
15.6 |
6.14 |
4.11 |
2.08 |
8.286 |
2.525 |
|
15 |
0.0571 |
1.450 |
17.5 |
6.90 |
3.26 |
1.65 |
10.45 |
3.184 |
|
16 |
0.0508 |
1.291 |
19.7 |
7.75 |
2.58 |
1.31 |
13.17 |
4.016 |
|
17 |
0.0453 |
1.150 |
22.1 |
8.70 |
2.05 |
1.04 |
16.61 |
5.064 |
|
18 |
0.0403 |
1.024 |
24.8 |
9.77 |
1.62 |
0.823 |
20.95 |
6.385 |
|
19 |
0.0359 |
0.912 |
27.9 |
11.0 |
1.29 |
0.653 |
26.42 |
8.051 |
|
20 |
0.0320 |
0.812 |
31.3 |
12.3 |
1.02 |
0.518 |
33.31 |
10.15 |
Does Battery Lose Voltage?
The voltage drop in the electrical system leads to energy loss as heat in the wiring. As a result, the wires will heat up, and the voltage at the devices will be lower than the voltage at the source. Most electrical appliances can operate within the range of their rated voltage. For instance, a 12V inverter does not necessarily require 12 volts. When an excessive voltage drops, the devices will stop working or malfunction. Plus, it can be a major safety concern. If the wire gets extremely hot, it can melt the insulation and cause a fire.
The acceptable voltage drop directly depends on the devices in the system. It's best to check the electronics operating manuals to determine the specific voltage requirements. The voltage drop is related to the safety of the electrical system. The small voltage drop should not be a major fire hazard. As per the National Electric Code (NEC), the voltage drop should be less than 5% of the source.
But does the battery lose voltage? Well, yes. Batteries lose voltage when they're used up. When the battery discharges, the voltage across its terminals decreases, and internal resistance in the battery increases. However, the rate of the voltage loss will depend on the appliance it is powering and the battery chemistry. For example, rechargeable batteries maintain their voltage relatively long compared to non-rechargeable batteries that steadily lose their voltage.
A good and healthy battery generally has a voltage of 12.6V to 12.8V when fully charged. When it is put through the load test equal to CCA, the voltage drops from 9.6V to 10.5V, depending on the ambient temperature. Once the load is removed, the voltage shoots back to nearly 12.6V.
What Are The Symptoms of Voltage Drop?
While the voltage drop symptoms vary depending on the circuit and severity of the voltage drop, here are some common ones:
- Sluggish electrical devices
- High sensor or computer voltages
- Inoperative electrical parts
- Excessive radio interference or noises
- Repeated AC compressor clutch failure
- False trouble codes in on-board memory board
- Damaged drivetrain parts
- Transmission cable failures
Jackery Portable Power Stations and Jackery SolarSaga Solar Panels can be connected via solar cables to supply stable electricity to electrical appliances. With the correct wiring size, you can connect the appliance to the output ports and start charging them. The best part about Jackery Portable Power Station is the ChargeShield technology that boosts the battery life by 50%.
Jackery Portable Power Stations Explained
Jackery is a well-known and reputable brand that manufactures highly efficient solar generators, portable power stations, and solar panels. The Jackery Portable Power Stations are battery-powered inverter generators for camping, emergencies, home backup, and RV life. They can be connected to the Jackery SolarSaga Solar Panels to recharge the battery and charge appliances.
The Jackery SolarSaga Solar Panels absorb direct sunlight that falls on the monocrystalline silicon solar cells and convert the solar energy to DC electricity. The Jackery Portable Power Stations then convert the DC to AC electricity and store the power in the battery backup. You can plug the appliances into the output ports to charge them without any hassle.
The Jackery Portable Power Stations are built with all-round safety. They feature 12 layers of protection, top shock resistant level 9, 94V-0 fire rating, and 9 temperature sensors to improve the overall safety of the appliances when charging. Here are a few popular Jackery Portable Power Stations for different usage scenarios.
Jackery Explorer 3000 Pro Portable Power Station
If you are looking for a large portable power station that can act as an emergency home battery backup power solution or a charging solution for extended outdoor trips, the Jackery Explorer 3000 Pro Portable Power Station makes more sense. It can supply stable electricity to 99% of electrical appliances when there's a power outage, or no nearby outlet is available.
The portable power station can be recharged with the help of Jackery SolarSaga Solar Panels, a car charger, and a wall outlet. It operates at 43.2V, and the fully charged BMS ensures a safe power supply for the appliances. Once fully charged, the portable power station can charge a refrigerator (300W) for 8.5 hours, AC (1000W) for 2.5 hours, and CPAP machines (60W) for 42.8 hours.
Customer Review
“We got the 3000 Pro with 4*200-watt panels. Since then, I've tried out my washing machine, gas dryer, and electric lawn mower and charged my phone. I've even charged the generator while powering devices with it. My idea of what solar and batteries can do has been greatly expanded. This unit delivers real power.” — P.V.
Jackery Explorer 2000 Pro Portable Power Station
The powerful Jackery Explorer 2000 Pro Portable Power Station is another charging solution that simultaneously charges up to 8 devices. It's ideal for long-term power outages when you need a safe power supply for your appliances or when you're planning a long camping or RV trip. The ergonomic design and foldable handle make it easy to move the power station from one place to another.
The superb BMS technology offers short circuit protection, temperature and voltage control, and other advanced safety operations. Its top shock resistance level 9 drop resistance makes it strong beyond imagination. With the Jackery Explorer 2000 Pro Portable Power Station, you can charge a refrigerator (300W) for 6.1 hours, AC (1000W) for 1.8 hours, and CPAP machines (60W) for 30.6 hours.
Customer Review
“Peace of mind knowing we have a backup in the event of a power failure. Very nice, powerful unit that charges quickly. Have run several appliances in the house. Hopefully, that will go well. I have purchased a second Explorer 2000 Pro to alternate when one needs recharging with the solar panels. We are now prepared for an emergency. Highly recommended.” — Richard W.
Jackery Explorer 2000 Plus Portable Power Station
If you are unsure which battery capacity is ideal for your needs, the expandable Jackery Explorer 2000 Plus Portable Power Station might be a reliable choice. Its built-in LiFePO4 battery has a 10-year lifespan and long-lasting reliability, making the portable power station ideal for various scenarios like home emergencies, outdoor trips, etc.
The ChargeShield technology offers fast and safe charging with 12 protective algorithms, 4 types of physical safety protection, and 62 protective mechanisms. The unique variable speed charging algorithm ensures safety and increases the battery lifespan by 50%. With the portable power station, you can charge a refrigerator (300W) for 5.7 hours, AC (1000W) for 1.7 hours, and CPAP machines (60W) for 28.9 hours.
Customer Review
“My husband uses an oxygen concentrator at night. The unit quickly charged up, and testing has shown it will power the concentrator for 7.1 hours, which will get him through the night in an emergency. It has been in storage for the last 30 days and is showing a full charge as of this date. I am happy with the purchase.” — Judy Browne.
How to Fix The Voltage Drop?
The excessive voltage drop in the circuit can cause flickering or dimming lights, heaters heating poorly, and motors running hotter than usual. As a result, the load will work harder with less voltage pushing the current. Thankfully, there are many ways to fix the voltage drop.
Rewire The System
A straightforward way to reduce the load current in the system is to rewire it. Suppose everything is working well, but when you plug in a new device, something starts malfunctioning or stops working. If you want to reduce the voltage drop, simply unplug the appliance. However, if it happens frequently, you might need a permanent solution.
Reduce the Wiring Resistance
Another way to reduce the voltage drop is to decrease the wiring resistance. You can do this either by using a thick gauge wire or by reducing the length of the wire.
Install Voltage Drop Compensator
Installing the voltage drop compensator at the end of the cable with the highest voltage drop will help you monitor and adjust the voltage. As a result, it will ensure the output voltage supply is always maintained at less than 1% of the nominal voltage.
Voltage Drop Tests
The voltage drop directly depends on the current flow. It's hard to measure voltage drop if you are not operating the circuit with current flowing through it. Digital multimeter tests do not generally give accurate voltage drops in the circuit.
Certain open circuit problems, such as disconnected or broken wires or connections, stop current flow. Once you've fixed this, you can switch on the circuit and check the voltage drop. Lastly, you can check the current flowing through the circuit to see if it is healthy.
Despite being resistance-free, most wires and cables contain at least some kind of voltage drop. If the manuals do not list the voltage drop values, you can consider 0.00V across connections, 0.20V across wires or cables, 0.30V across switches, and 0.10V at the ground.
When testing low-current circuits, you'll also need a high-impedance digital multimeter. It may load a low-current circuit to give an incorrect or no reading. Using a professional-grade digital multimeter can help you accurately measure the voltage drop. If the digital multimeter does not have auto-reading capability, you can use a low-voltage scale for voltage drop testing.
How to Calculate Voltage Drop FAQs
What is the formula for calculating voltage drop?
Ohm's Law states that the voltage drop across a load or conductor is equal to the product of resistance and current. Here is the mathematical representation of the formula: VD = R × I.
How to calculate voltage drop over distance?
If you want to calculate voltage drop over distance, multiply the distance (or the length of one wire in feet) by the current (measured in amps) by the volt loss for the kind of current and wire to be used by one over the total number of conductors per phase. Lastly, you can put a decimal point in front of the last six digits to get the volt loss.
For example, if we have a 6 AWG three-phase copper wire (180 feet in length), 40 amp load at 80% power factor, the volt loss can be calculated as follows:
Volt Loss = 180 × 40 × 745 × (1 ÷ 1) = 5364000
Put the decimal six places to the left: 5.364000 to get the expected volt loss.
What is the voltage drop in a 120-volt circuit?
For a 120V and 15A circuit, there should be no more than a 6-volt drop at the furthest outlet, even when the circuit is fully loaded. The National Electrical Code mentions that a 5% drop at the furthest outlet in the branch wiring circuit is passable for normal efficiency.
How to find voltage drop with a multimeter?
If you want to measure the voltage drop with a multimeter in the positive battery cable, you can start by holding the red probe lead on the positive battery end and the black probe where the positive battery connects. This will help you measure the voltage drop with a multimeter.
How to size wire for voltage drop?
The basic formula to calculate the wire size for voltage drop is:
Wire Size = 2 x K x L x Amps/Acceptable Voltage Drop
Where,
The value of K for copper is 12.9 and 21.2 for aluminum
L is the one-way wire length in feet
Final Thoughts
Some part of electricity is lost between the point of use and the power meter, known as voltage drop. The NEC recommends the maximum voltage drop to be 5% across branch circuits and feeders and around 3% across the branch circuits. Understanding how to calculate the voltage drop will help you ensure the system performs well and is safe to use.
If you're choosing a portable power solution for your appliances, you'll need to understand the voltage drop and select the proper wire size. Jackery Portable Power Stations are built with safety in mind. The portable power stations have highly stable and safe batteries to supply electricity to the home or outdoor appliances, including refrigerators, ACs, water heaters, etc.
Leave a comment