Electric vehicles (EVs) are taking over our roads. From city cars to long-range SUVs—more people are plugging in rather than filling up. It is no surprise, though. EVs are clean, quiet and cheaper to run than gas-powered cars.
But while we talk about charging stations or battery size—there is a quiet problem hiding behind the scenes: voltage drop. It may not sound normal, but it plays a huge role in how fast your EV charges—or how slow it does.
In this article below—we will explain what a voltage drop is, how it affects EV chargers, and why choosing the right cables matters more than people think.
What exactly happens when the voltage drops?
Think of the electricity like a team of runners passing a baton down a long track. The goal? To deliver full power from your home’s electrical panel to your EV charger.
But here is the catch—the longer the track, the harder the route and the more tired the runners get. It might not be as strong as it started by the time the baton (or electricity) reaches the finish line.
That loss of power along the way is what we call a voltage drop.
It is not a glitch. It is just how physics works. Wires have resistance. The longer the thinner the wire, the harder it is for electricity to move through. The result? Less voltage reaches the charger than what you started with.
Why this matters for EV owners
Imagine coming home after a long day and plugging in your EV, expecting a full charge by morning. But the next morning, you wake up and find the battery is only half charged. Frustrating right?
Often, the reason is not the charger or the car. It is the cable. If the wire runs from your panel to your charger is long and the wire is not thick enough—voltage drops. And the power delivered to your car is less than it should be.
Even small losses add up over time. Charging slows down, and energy is wasted as heat. And your charger works harder than it needs to.
In short, poor cable planning can kill your charging speed without even realising it.
Long runs make the problem worse
Here is where people get it wrong. A lot of EV chargers are installed far from the main electrical panel. Maybe in a detached garage or a parking lot. Or even out by the driveway.
That means the cable run is long. And the longer it is, the more voltage drop you get. Now, for short runs, it is not a huge issue. But once you start running cable over 50 or 100 feet, voltage drop becomes a real concern.
Let’s say you use a 50-foot run of standard 10-gauge wire for a level 2 charger. You might lose 4 to 5% of your voltage. On a 240V system, that is a big chunk, and your car will notice.
Thicker wires offer less drop
The most effective solutions? Use thicker cables.
Thicker wires have lower resistance, which means less voltage drop. That is why electricians recommend “upsizing” the cable if the distance is long. Instead of 10-gauge wire, you might use 8-gauge or even 6-gauge—depending on the run.
It may cost a little more upfront but you will get better charging speeds and more efficiency. Over time, it pays off.
Also, remember that some EVs and chargers draw higher amps—up to 40A or more. These higher current makes the voltage drop even worse, which makes proper cabling even more important.
EV charging standards and voltage needs
Let’s look at what most EV chargers expect. A typical Level 2 charger runs on 240 volts and can pull 30 to 40 amps.
Now, imagine the charger only gets 220 volts because of the big voltage drop. It may still work but it might not be able to deliver the full power it is designed for. Some EVs might reduce their intake to protect the battery. Others might charge but more slowly than expected.
Even smart chargers with load balancing can’t fix this. They need the right voltage to function as designed. The bottom line? Your charging suffers if the cable can’t handle the load or is too long without being upsized.
Heat is another hidden problem
Voltage drop does not just slow down charging—it also causes heat.
It generates heat when electricity encounters resistance. So, a long cable run with the wrong size not only drops voltage, but it also warms up. And the heat can be dangerous if it builds up.
Over time, cables can degrade. Insulation may crack. And in extreme cases, it could lead to overheating or even fire risk. That is why codes exist to limit how much voltage drop is acceptable.
Most electricians aim for less than 3% voltage drop for power-hungry circuits like EV chargers. If you are losing more than that, it is time to re-check the installation.
Don’t just rely on the charger
Many people think that as long as they buy a high-quality EV charger, they are good to go. But even the best charger in the world can’t work well with a poor cable setup.
Your charging speed depends on the full path—from your electrical panel, through the cable, into the charger and finally into the car.
So while brands and features matter—the wiring behind the scenes matters just as much. If you’re investing in smart home upgrades or digital display systems like a LED video wall, you wouldn’t skimp on wiring. Your EV charger deserves the same attention.
It is not just about the charging speed
Yes, changing matters. But there is more to this than just speed.
Voltage drop also affects efficiency. When the voltage drops, more energy is wasted. You might end up paying more on your electric bill to get the same charge. That wasted power becomes heat and wear on your charger.
It is not just slower—it is costlier too.
And adds up over the long run. Well-designed setup charges faster, wastes less and runs cooler. That means less wear on the system and more savings for you.
Planning for the future
Let’s say your setup works today. Great. But what about in five years?
What if you upgrade to a larger EV? Or install a second charger for a second vehicle? Or what if your utility company offers faster charging incentives?
If your cable can’t handle more power, you may have to rip out the old wires and install new ones. That’s why it’s smart to overbuild a little. Even if your EV pulls only 30 amps today, plan for 50 amps.
Forward planning applies to everything—from EV chargers to LED display panels and other high-power devices you might add to your home or business in the future.
What you should do
If you are planning to install an EV charger—or already have one—take a moment to check:
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How far is the charger from the main panel?
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What size wire was used?
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How much power does your EV need?
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Are you getting the full speed your charger promises?
Talk to a licensed electrician if something feels off. Ask them to measure the voltage at the charger while it is running. It is time to consider a wiring upgrade if it is dropping too much.
Bottom line
EVs are the future. And fast, reliable home charging is a big part of that. But many people overlook one small detail—voltage drop—that makes a big difference.
If your charger feels slower than it should be, or if your EV takes longer than expected to fill up, the problem might not be the charger or the car. It could be hiding in the cables.
Long runs, undersized wires, and poor planning all lead to power loss. That means slower charging, higher bills, and more wear on your equipment. But the fix is simple: use the right cables, plan ahead, and build for the future.
Because when it comes to EV charging—every volt matters. And just like with a high-performance video wall system, a strong power setup makes all the difference.
