Using the Supplied EVSE Cable for Regular Charging

Now that deliveries of the Nissan Leaf are picking up in the UK our thoughts are now likely to be turning towards sorting out and installing our preferred charging solutions. Options suggested by Nissan are:
1) The car is supplied with its own EVSE (Electric Vehicle Supply Equipment) charging cable. You can simply plug one end of this cable in to a standard 13A socket and the other end in to the cars AC charging port. Although the on board charger can charge at 3.6kW (16A @ 230VAC) this charging cable will restrict charging rate to just 10A and so, from empty, it would take about 11hrs to fully charge as the battery pack has a capacity of 24kWh. This cable can be put in the boot so that, in theory, the car can then be charged anywhere you have access to a 13A socket. I say “in theory” – I will explain this later.
2) As an alternative at home, you can have a quick charger installed. The quick charger must be installed on to a separate circuit in the house. It allows you to make full use of the 3.6kW charger and allows charging at 3.6kW (approx 16A). This will charge an empty Nissan Leaf in about 7.5 hrs. As this Home Pod (as it is often called) is a fixed installation it has to be professionally installed. Nissan’s partner for Home Pod installation is British Gas who charge £995 (correct as of April 2011) for installation assuming no special requirements or remedial work is required. This method is often called “Quick Charging” not to be confused with “Fast Charging” which is option 3.

3) The third charging method is called “Fast Charging”. This is a completely different method. Instead of using the on board charger Fast Charging uses 400V DC to charge the batteries directly via commercial charging stations. These stations have their own charger bypassing the cars on board charger. As its name suggests, this method is very fast indeed taking just 30 minutes to charge to 80% from empty. It plugs in to the DC charging port on the car, using a different plug to the AC port, and can charge at 50kW. It is intended for use on long trips and is not intended for everyday use. In fact, used too often Fast Charging can reduce the life of the batteries so other methods should be used whenever possible.

Nissan intend and expect most Nissan Leaf owners to use option 2 (Quick charging at 16A) but at £995 for installation for the Home Pod it is quite likely that many people will try to make do with the supplied EVSE cable and just accept a slower charging time. If you intend not to install a Home Pod then there are some very serious considerations that you are going to need to take into account.

So what are these issues surrounding using the 10A EVSE supplied with the car for everyday charging?

The car itself has no issues with charging at 10A. In fact, there is very little difference in impact on the batteries when charging at 10A or at 16A. It is really just a matter of charge time. Where the potential problems exist is in the sockets, wiring and circuit protection in the house. Get this wrong and it isn’t at all out of the question for your house to burn down! No, this is not just scaremongering, I promise you!

For me, the biggest issue is the 10A with the EVSE. In the UK we have 13A house sockets don’t we? Surely a 13A socket can cope with a 10A charger – can’t it? The only honest answer to this is generally NO! Surprised? Most people might assume the answer should be YES but to understand why the answer is NO you have to understand a little of the basics of how a house is wired.

This is really important to understand right from the start… in most UK households 13A sockets are on a ring main. I am no electrician but you can think of a ring main as basically a ring of cable that runs around the house to which the sockets are attached. The ring is attached to the consumer unit at each end to a single fuse or circuit breaker. In fact, there are usually several rings in a house; one for each floor and often one for the kitchen. There is usually a single 30A fuse or to a 32A circuit breaker for each ring. This is the key… a single socket might be rated at 13A (3kW) but each ring has a capacity of just 30 or 32A. If you plug a Nissan Leaf into a ring main socket then it takes up 30% of the maximum capacity of that ring. If there are any large loads on that ring (or lots of little loads) then you are then in danger of overloading that ring and blowing the fuse, tripping the circuit breaker or worse heating up the wiring with the risk of fire.

Well, that is OK… just limit what you run on the ring at the same time as charging your Nissan Leaf and all should be well shouldn’t it? Well, the only honest answer to this is possibly.
OK, you have found out what ring your charging socket is on and you have limited the other loads on that ring so the fuse doesn’t blow. You plug in your Nissan Leaf using the EVSE cable and start charging. All well and good. The problem that now exists is one of an inherent weakness of any house wiring… age and condition. If the house was newly wired, all connections 100% solid and all equipment in 100% tip top condition then although it wouldn’t be advised, you could be reasonably happy that it was safe. Who has a house like that? Most houses have old wiring, sometimes very old. Most sockets haven’t had their wiring and connections checked since they were installed, often decades ago. Wiring like that is a potential time-bomb just waiting to go off, particularly under heavy loads. Often, the only thing that is preventing trouble is the fact that most loads on the ring (except perhaps the kitchen ring) are relatively low and/or transient. Increasing the load on the ring by plugging in a 10A car charger and leaving it on for hours at a time, as you are very likely to do, increases the chances of sparks and/or overheating potentially resulting in a house fire.
So, it is not unreasonable to say that, in spite of what we all might think, charging a Nissan Leaf with the EVSE cable, on a normal ring socket, is a potentially risky business and strongly advised against on a regular basis. If you are at a friend’s house and need to charge up then I suppose most of us might take the risk for a short period. However, I would strongly advise against leaving it charging overnight on an unchecked ring main socket (a normal 13A socket in a house or garage).
For many of you this may come as a huge disappointment. You were relying on being able to use the EVSE cable for everyday charging and here and now I am saying that you shouldn’t. Well, there is an answer so don’t fret just yet.
As I have said already, I am no electrician and you should always get your own advice from a qualified electrician as not all houses and circumstances are the same. However, I have done just that for my own circumstances and so I can tell you what I have done to reduce the risk of a fire or blown fuses. The simple answer is not to use a socket on a ring main. Put in a dedicated circuit, attached to its own fuse or circuit breaker in the consumer unit, and if you are having it put in especially for charging the car then the wiring will be new and the connections solid. I have put in new cabling from the consumer unit to a waterproof, lockable,  double 13A socket attached to the outside wall of my garage. It goes to a new, dedicated, 16A circuit breaker and uses 2.5mm cable rated at 27A. This will allow me to charge the Nissan Leaf through that dedicated socket at 10A continuously without risk of either blowing the fuse or overheating old cables. Now, if I wanted to uprate the circuit breaker to a 32A and replace the cable to one that is higher rated I could then either charge 2 x Nissan Leaf cars simultaneously or replace the 13A sockets with a Home Pod. Either way the cabling is new and there is no risk to the rest of the house. I got the new circuit put in by a local qualified electrician for under £100 all in.

You must get your own advice, but for me, this seems to be a safe alternative to installing a Home Pod until I have had the car for a while and I know my charging habits and requirements. Moreover, very soon, British Gas will not be the only provider of Home Pods, and I want to wait a while, until the market has opened up, before opting for any particular Home Pod Quick Charge solution.

So, can you use the EVSE cable for everyday, regular charging at home? Yes, but do it safely and get a dedicated 16A circuit installed by a qualified electrician. It won’t cost anything like the Home Pod and might prevent your house burning down!

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