Oct 6, 2022
How to Charge Two or Multiple Electric Cars at Home?
First of all: Congratulations!
You have not one, but two electric cars - a true pioneer!
Or perhaps you have guests and they brought their EV for the ride. But now you need to charge two vehicles. So, what’s the best way?
Well there’s really only two options - both pretty straightforward.
The first is to simply take turns. Plug one EV in, wait for it to finish charging. Then run out, switch the cables, and charge the second EV.
Option two is to kit your home with two chargers: now you can fully charge two electric cars at home at the same time!
I told you, it's straightforward. 🙂
But there may be some things you don’t expect along the way. Here you can figure out which option is really best for you.
Option 1: One Charger, Two Cars
Here’s a secret. You already have a charge point installed at home for your first car.
Who says you can’t use it to charge a second car? After all, sharing is caring, right?
Plug in the first electric vehicle and when it's done, plug in the next electric vehicle. Just please don’t forget to set yourself a reminder to swap the charging cable!
Of course running around in your pyjamas in the middle of the night may be a pain - especially if you have to move your cars around to reach the charge point. But this option is always available plus it saves you a bit of money on a second charger.
If you have one electric vehicle and only the occasional guest, this is probably the best option.
Option 2: Two Chargers, Two Cars
If you have two EVs living full time on your driveway, or you simply don’t like the idea of balancing an umbrella in the crook of your neck while juggling charging cable, car keys and whatnot in the whipping rain, then two charging stations may be the way to go.
Once set up, you have the luxury of charging two electric cars at home at the same time. Good chargers make this experience seamless by allowing you to prioritise who gets to charge when or for how long. All go-e Chargers give you this control through the app.
Best of all though, you never have to remember to swap cables!
So can you just throw a second charging station onto the wall?
There’s one important consideration.
Avoid Blowing Your Fuse
Each home has a limit on how much power (current) can be drawn at any given time. Exceed the limit and you blow the main fuse.
Imagine you have all the lights on, the washing machine whirring away and dinner simmering on the stove. It’s a lot of power being drawn at once, but it won’t blow the fuse.
Now imagine an 11 kW charger also hooked up to this home grid. That could tip the scales.
When installing the wallbox, the electrician first makes sure that there is enough ’space’ on the main fuse to accommodate it.
This way you can run your kettle and oven and have your feet up in front of the telly while charging your EV at full power, without a worry!
As an additional level of safety, the electrician installs a dedicated fuse (type A RCD) on the fuse board for every wallbox (for an 11 kW charger that might be a 16 amp fuse).
Each time you add another charger, the electrician has to check the remaining capacity on the main fuse. All appliances running at the same time ideally shouldn’t exceed the capacity of the main fuse. (will be in hint box in Strapi)
But what if your main fuse is too small? Are you stuck with one charger forever?
Not at all. You could increase the capacity of your main fuse. This means getting an electrician to upgrade the fuse and potentially the consumer unit and meter tails. It can become quite expensive though.
Load Balancing to Charge Two EVs or More
If touching your household electrics sounds like too much trouble, don’t worry. You can still have two charging stations set up.
How? By relying on some clever load management.
This basically means telling your charging station how much power it can draw without upsetting our little friend, the main fuse. And even if your fuse isn’t a limiting factor, load management helps you control the power consumption of your charger whenever you need to.
Load management in charging stations is more often called load balancing. It's a fancy way of saying that multiple chargers share the available power. It's an essential feature to look out for if you’re thinking of growing your charger family.
Chargers with load balancing features are able to talk to each other.
No - not about the weather.
They discuss how much power is available and how much juice their car’s need, or even who gets served first. Importantly, they make sure they don’t exceed the power they’ve been allowed. Whether you have 11 kW or 22 kW home chargers, as long as there is load balancing going on, you don’t have to worry about blowing the main fuse! In other words, you can bake your cake and eat it (while the dishwasher is running and two EVs are charging overnight).
Depending on the type of load balancing, your chargers can even talk to other smart home systems - such as a solar panel installation.
So yes, maybe they do talk about the weather. 😅
What does Load Balancing Look Like?
Let’s say you have two 11 kW chargers hooked up on your driveway. But the main fuse on your house can only really take one charger (plus household appliances) working at full power.
You have one electric vehicle pull up and start charging. The charger starts pumping out power at the full 11 kW.
Then the second electric vehicle pulls up and connects to the second charger.
Thanks to load balancing, each charger now only delivers half the power to their EVs. That’s 5.5 kW each. Or 6 kW and 5 kW. Or 4 kW and 7 kW. Who says you can’t love one EV more than the other?
It also doesn’t matter if you have two Teslas or a Tesla and a Zoe. It works the same way. Of course your EV will also have its own limitation on how much power it can accept. But that’s a different topic.
Bottom line: one car can charge flat out or two cars can reach a full charge by sharing the power. Either way, you don’t have to worry about blowing your fuse.
How Many EV Chargers Is Too Many Chargers?
What if I have three chargers? Four chargers? Five?
What if I’m actually a carpark owner? How many electric vehicles can be charged at once?
It works in exactly the same way. In fact, this is where load balancing becomes all the more critical.
As a carpark owner, you may not have household appliances to worry about, but many more clients who need their cars charged. You may have a large fuse fitted, but a utilisation limit set by your electricity provider.
Load balancing ensures not only that you don’t blow the fuse, but that your users also don’t exceed the limit set by your electricity provider. This way there are no nasty surprises waiting in your monthly electricity bill!
In a similar way, load balancing allows you to set caps on your users at times when electricity is especially expensive.
Can You Daisy Chain Your EV Chargers?
Depending on the physical location of your charging stations, your electrician has several options regarding how they hook them all up.
If the chargers are all located on a single wall, it may make sense for them to be daisy chained on one circuit so that they share the same circuit breaker. This means that the cable supplying electricity enters one charger and out again, into the next, and so on.
Don’t be fooled, you don’t need a special type of charger to do this. Your electrician can easily set this up with a simple junction box.
But … Here is the big “but”.
Daisy chaining may not always be the best solution.
If one charger fails or if the fuse blows, all chargers on the circuit are out of action. Having one cable snaking in and out of chargers that are located far apart (e.g. on pillars in an underground carpark) may also be cumbersome.
The alternative is to have individual circuits for chargers or groups of chargers. It depends on your situation and the electrician can best advise.
Using a Fixed and Portable Charger at the Same Time?
What if you want to use a portable charger at home at the same time as your wall mounted charger? As long as they both support some form of load balancing, you’re fine.
I’m guessing you’ve read this far because you want to charge two electric cars at home.
If convenience and comfort are high on your list of priorities, then investing a little bit more on a second charger is a solid option. After all, who wants to deal with moving cars or charging cables back and forth?
So what do you really need to do?
- Check with your electrician how much ‘space’ you have on your main fuse.
This helps decide the size of your second charger: e.g. 22kW or 11kW. Bear in mind that when you’re charging two vehicles at the same time, you will most likely be sharing the available power - so pick your size accordingly.
- Select a charger
Make sure it has load balancing and that it can communicate with your existing charger. The go-e Charger Gemini and Gemini flex pair well together!
- Get a qualified electrician to install and set up the charger
The electrician shall ensure an appropriate fuse and miniature circuit breakers are installed. The go-e Charger Gemini flex is a portable charger - no electrician needed here, you can plug this in yourself.
Now plug in both cars and lean back. Load balancing will take care of the rest!
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