1m vs 100m Cable Charging an Electric Car
Now, electric cars like this usually come with a 5 to 7 meter cable. But what about 100 meters? What actually happens? Now, when it comes to electric cars, the longer the cable is, the longer it will take to charge and the less likely it is to charge properly. But why is that? So, we’re going to test charging my car with a 5 m, 25 m, and then 100 m cable to see what actually happens. Now, you might be wondering from the title of this video if it’s possible to charge with a 1 m cable and also you might be wondering why. You maybe have never seen one. Now, in theory, you can charge an electric car with just a 1 m cable. From electrical point of view, there’s nothing wrong with it. It actually is more efficient to do that. A shorter cable means less resistance, less voltage drop, and less heat wasted. But let’s explain why there are no charge cables at this length. Number one is obvious. It would be hard to get a cable close enough to the charger. Number two is that there are a multitude of electric cars out now which all have charge flaps in different locations which is why longer cables exist because the charger is fixed. So it has to accommodate all different types of cars. Number three, but most importantly, there are a set of standards that all EV chargers have to meet to make sure they are safe and usable. The main standards for EV charging are BS62196-2, IEC61851 and BS7671. First rule is vehicle reach. Cables need to be long enough to reach the charge inlet from any reasonable parking condition. A 1 m lead simply can’t do that unless your charger is close and pressed up to the wall. The second is strain relief and bend radius. The IEC standard says that the cable has to have enough slack to prevent mechanical stress on the socket and it has to bend safely without damaging the insulation. A 1 m lead will be under tension every time you plug it in, so it’ll instantly fail. And the third rule is safe routting and protection. BS7671 section 22 requires that cables are positioned to reduce trip hazards and mechanical damage. With 1 m cables, there’s no room to play with when you want to avoid damaging the bodywork on the car. So, in contrast to that, why aren’t cables just really long? Now, for this, we need to dive into the math and physics a little bit. Now, it wasn’t my strongest subject when I was studying at university, but I’m going to try and explain it in the simplest way possible. So, for that, let’s go to the garage. Now, this little device will show me live current, power, and voltage drop when the charger is plugged into the wall socket. Now, it’s not lab grade equipment, but it’s good for a little demo to show you what happens. Now, I’ve plugged it into my wall here on my garage. Now, you can go through different modes to see what power and current is being drawn and the voltage. As we’re now going to plug into the car, let’s see what the difference is as to how much that goes up by. Now, for example, my Nissan Leaf could pull about 10 amps from the wall when it’s charging and maybe around 236 volts. So, let’s see what happens when I turn it on and start charging from the wall. As you can see, it’s not pulling much current at the moment because the charging timer is on. So, when I turn off the charging timer, the current will shoot up. So, let’s see what’s happening. Now, here’s where the physics come in. Now, the longer the cable is, the more resistance it will have. So therefore, the more voltage drop you’re expected to see on this meter, for example. Now, at the moment, we got nearly 9.5 amps running through it, which is quite high. We’re on 239.3 volt. And before we plugged it in, it was around 244 volt. 2,287 W. Is that That’s quite high, which is the equivalent of 2.3 kW. So, this is my standard setup in my garage going from the granny charger being plugged into the car. And as you can see, it’s gone down by around four or five volts. So, let’s see when we extend that cable what happens. Okay, as we’ve moved to a new location, let’s get a standard voltage reading for this circuit before we plug any charges in. As you can see, it hovers around 236 volts. So, let’s check with a 5 m cable how much voltage drop happens and if the car is able to charge. Okay, now I’ve got the same power meter to check what the voltage is at the end of this 5 m length extension cable. So at the moment it’s on 232.4. So if I bring up the difference now to what we saw as a baseline figure, you can see how much that drops in terms of voltage over just 5 m. So let’s plug it in now and see what happens. So the charging timer is on. So let’s turn that off. Right now I’m getting 9.6 amps, which is what we’re expected to see. and 225 224 volts. So, it has dropped a bit from the wall, which is very interesting. The cable at the moment is cool. Obviously, this is not a safe setup. I’m just doing it for demonstration purposes, but in theory, a 5 m long cable should be fine. Later, we’ll see what happens at 100 m. But first, things get really interesting when you start looking at a little bit longer than 5 m. Let me show you. Okay, next up is my 25 m long extension cable. Now, to be honest with you, I’ve not checked the safety of this and I’ve got no idea if it’s 2.5 mm squared cable or not. So, I do not recommend you do this at all, but one rule is that you should always unwind the cable fully to avoid heat buildup and any safety issues. So, that’s what I’ve done here. Let’s plug in the meter to give a accurate reading on the voltage drop if there is any. Okay, let’s turn off the charging timer and let’s see what the actual pull of the current is to see if it actually charges or not as well. So, interestingly enough, let me show you what the voltage drop is. As you can see here, we’re on 220 volts around that number. So, it’s dropped significantly since we checked the wall voltage after 25 m. It’s pulling 9.8 amps, which is quite high. And the charger seems okay with that 25 m distance, which is very interesting. So, if charging is okay at 25 m, why do manufacturers only supply you with a 5 m cable? So, your car probably came with two cables. The granny charger that plugs into a 3 pin socket and a thicker type 2 cable that goes into public chargers. The granny charger is usually 3 to 5 m long, while type 2 cables are typically 5 to 7 m long. And that’s not just a coincidence either. Longer cables use more copper, and that makes them more expensive. So, with the manufacturers, there’s already a cost trade-off there. They’re also a lot heavier, so especially type two cables with thicker cable cores which require them to handle 32 amps or even more. And beyond 7 m long, it actually starts to become a bit awkward to carry around and store and adds weight to your car a little bit too. But most importantly, at that length, the car is still able to receive the full power from the charger to the charging port without losing any voltage or creating much heat. And that’s why no one makes a super long home charger cable. It’s a bit unsafe and inefficient. So, what is the longest charge cable that you can charge your electric car with? And what happens when I try a 100 m cable? But before we get on to that, the longest cable that you can theoretically charge your car with. The longest cable you can charge your car with depends on the thickness of the cable and it ultimately depends on how much current your car is drawing from when it’s charging. But every extra meter will add resistance to the cable. Resistance creates voltage drop and voltage drops creates heat and heat becomes unsafe. Okay, so with all that in mind, you might think that the longer the cable is, the longer it takes to charge and the slower the charging speed, right? Well, not exactly. At this point, this is where the 25 m limit comes in. And at that point, it doesn’t just charge slower, it could actually just stop charging altogether because it’s simply not safe. And to prove that, let’s charge with 100 m cables to see what actually happens. [Applause] All right, I’ll admit I couldn’t find a single 100 m cable. I don’t think that’s even allowed in the UK. So, I’ve daisy chained lots of extension cables together. Now, I definitely don’t recommend this along with all the other stuff that I’m doing on this video. On this video, I’m just doing a control test to see what actually happens when you push a granny charger to its limits. So, the car’s plugged in. The light saying that the charging timer is on. So, let’s look at our little meter and see what actually is going on there. So, let’s bring it to our normal 234 volts we’re getting through, but that’s with no current at the moment. So, let me go and turn off the charging timer and let’s see if it charges and what’s going on. The charger says it’s actually ready, which is incredible. So, let’s go and turn off the charging timer and see what actually happens with the car. Okay, charging timer off. Is it going to explode? It says charging. That’s incredible. That is incredible. So, we’re down 209 volts. 210 volts. We’re doing 9.7 amps of current running through, which is madness. I can’t believe that works. And we’re charging. Now, I’ll be honest. I tried this before when I did my video where I ran out of the battery completely and was hoping to get someone to plug in and charge my car, but what actually happened was that it didn’t work on that day. Now, I think the one rule from that to take is that the cables should always be unwound completely. And that’s why I think it didn’t work on the day cuz the charger said it wasn’t safe to charge. So, incredibly, it does work. But do not do this at home. But of course, remember that the charger has a safety limit. So, any more than this and it probably won’t work at all. Okay. At this point, I need to give you a full disclaimer. I ran out of extension cables. So, when I daisy changed everything out, it totaled about 60 m and the car was still charging. And the meter showed around 209 volts and charged at around 2,000 watts, which means we lost around 27 volts from the wall to the extension cable. Any more length, heat buildup, or bad connections would result in the charger not working. So in theory, then what would actually happen at 100 m? 25 m test, the voltage dropped around 16 volt. Scale that up to 100 m on a 1.5 mm squared cable and you’re looking at roughly 64 volt lost. So 236 – 64 you get about 172 V and this is far outside the safe limits within the Granny charger cable. So at 100 m the safety systems within the granny charger will not allow the car to charge. So what did we learn here? Well, a 1 m cable is electrically fine but fails all the safety standards and is impractical really. A 3 meter cable is ideal if it reaches from the charger to the car. And around 10 meters, you start seeing some voltage drop off. And by 100 meters, the charger just refuses to work. So with that, watch this video next. And I look forward to seeing you on the next one. Peace out.
Are there reasons why you shouldn’t charge your car with a super long cable?
I thought I would try out to see how long a cable you can charge an electric car with.
Definitely do not try this at home.
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I’m Alex, a British guy sharing what it’s really like living with a budget electric car.
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📖 Chapters
00:00 Intro
00:23 is 1m possible?
02:14 testing explained
03:50 first test
04:54 second test
06:00 why shorter cables?
07:41 third test and conclusions
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