To Pod or not to Pod?

Now that our car looks like it is on the way (estimated delivery early April) we have to decide whether to get a Quick Charge Home Pod. British Gas (BG) are Nissan’s partner as pod suppliers and installers and so we had BG round to inspect our electrical system and to discuss how and where they would install a Home Pod.
The inspection took about 15 minutes. They checked the earth bonding to the water pipes and tested the RCD on the consumer unit. They then discussed where it would go… on the side wall of the garage looks like the best place.

So, having a pod installed is not going to be a problem. For us though, the real issue is whether we want a pod or not at all.

Before discussing our thoughts on that I just want to clarify a few facts.

Charging the Nissan Leaf by 230V, as it is in the UK, is done through the AC charging port at the front of the car. Under the flap at the front there are 2 charging ports; the one on the left (looking at it from the front) is a DC charging port for Fast Charging but it is the one on the right, the AC port, that we will be plugging in to for charging from the grid.

The Nissan Leaf currently comes with a battery charger built into the car. When charging from the mains it is this battery charger that is used for charging the battery. It is currently a 3.3kW charger and as such the fastest we can charge the Leaf from the mains will be at 3.3kW. Many people talk of amps when discussing charging and that is fine but using amps can be confusing and lead to some misunderstanding. I would like to clarify some of this terminology as it can muddy the water when talking about charging.

As I said, the built-in charger is a 3.3kW charger. The battery pack capacity is 24kWh. So, if the battery was empty and we could charge at the maximum power the charger can deliver of 3.3kW then it will take 24 / 3.3 = 7.27 hours. This then is the fastest you will ever be able to charge the Nissan Leaf from empty in the UK from the grid.

It would be good if we in the UK could just plug the supplied charging cable (EVSE cable) into the mains, plug the other end in to the cars AC port, and charge at 3.3kW. Unfortunately that is not possible. In the UK our mains sockets are rated at 13A or 13 amps… and that is where the problems start. There is that AMPS I talked about. So what is that all about? Most of the time people talk about 10A charging or 16A charging. So how does that relate to the 3.3kW I have just described? You need to know how to calculate the current (amps).

I am not an electrical specialist and so I am not going to try to explain the technical aspects of this. There are a lot of places on the net where you can learn about current in amps (A) , power in watts (W) or kilowatts (kW), voltage in volts (V) etc. However, I do want to explain a little about how this relates to the Nissan Leaf because there is a lot of confusion over this at the moment.

You can convert kW to A if you know the voltage. Here in the UK our grid voltage is meant to be about 230V so that is what I will use for the calculations. Amps is simply W / V. So, if the full power of the built-in charger is 3300W (3.3kW) then using the mains at 230V means the current (amps) is calculated as 3300W / 230V = 14.34A . So, 14.34A is the current when charging using the full 3.3kW of the built-in charger. The problem is that sockets in the UK are rated at 13A. So we cannot charge the Nissan Leaf using the mains at the full 3.3kW or we would blow fuses everywhere.

The solution to this is that the supplied EVSE cable has a clever box attached to it that tells the charger not to charge at the full 3.3kW. It tells the charger to charge at 2.3kW. So, using our calculation from above we can calculate the current as 2300W / 230V = 10A. 10A is under the 13A rating of a UK mains socket and so using the EVSE cable we can simply plug into a mains socket to charge but, as you see, it is at reduced power. Most people talk of “10A charging with the EVSE” and so this is where the 10A comes from. What will charging at 10A (or 2.3kW) do to our charging times – well, from empty charging the 24kWh battery at 2.3kW (10A) would mean a charge time of 24kWh / 2.3kW = 10.43 hours. So 10.5hrs is the quickest you will ever fully charge the Nissan Leaf from empty using the EVSE cable.

But what if I don’t want to charge at 2.3kW with the EVSE cable? What if I want to use the full capacity of the built-in charger at 3.3kW? For that you need a Home Pod installed. The Home Pod is not a charger. The charger used is still the same built-in charger that you use with the EVSE cable. It is simply a replacement for the EVSE cable and that clever box I said that was attached to it. The clever box on the EVSE cable tells the charger to charge at reduced power. Using the Home Pod it is the Home Pod that tells the charger to charge at full power… at 3.3kW. As we have seen, 3.3kW in the UK is just over 14A so it cannot be plugged in to the mains by a socket so it has to have its own 16A circuit and be wired directly in to the consumer unit.

So, some people talk of 16A charging with the Home Pod. That is not exactly true. Yes, it is installed to a 16A circuit but as you have seen, the fastest that the built-in charger can charge is 3.3kW or just over 14A. You can also see that by using a Home Pod the from empty to full charge time is reduced from about 10.5 hrs with the EVSE cable to about 7.25 hrs.

That has dealt with the facts about charging the Nissan Leaf and about what the Home Pod gives you. But do I want one? That is not so easy to answer. Installation costs £995 from British Gas and for what… a reduced charge time from empty from 10.5 to 7.25 hrs. Sounds good doesn’t it? Well, I am of the opinion that we should all be very careful about making this decision if you don’t want to potentially waste that £995, because I think a lot of people may not benefit much from that reduced charge time and so may prefer not to have the Home Pod installed.

Something that seems to be overlooked when considering charge times with an EV is that for the vast majority of the time the car will not be empty. In fact, given that the nature of an EV is that it is more suited to short journeys I can see that for the vast majority of times the car will not be anywhere near empty when charged. Also, the vast majority of charging will be done overnight. So, unless you regularly do 80-100 miles a day, is it not going to take the full 10.5 hrs to recharge using the EVSE cable and as it done overnight, charging time becomes rather irrelevant. OK, I accept that some people will be using their car differently and might regularly run it nearly flat and so in those cases the reduced charge time of a Pod might be useful. But for the rest of us, possibly the majority of us, charging at 10A (2.3kW) and charging over night, will be more than adequate.

In our case we also have a solar PV system which complicates things a little but with a solar PV system you want to charge at a rate less than PV system can supply to avoid the need to buy from the grid. In our case it is not ideal because the maximum capacity of our PV is 2kW so even charging at 2.3kW, using the EVSE cable, we are still importing a little from the grid and so for us, there is going to be no benefit from having a Home Pod just because we have solar. If, on the other hand, we had a solar PV system of bigger than 3.5kW then having a Home Pod would mean that the full 3.3kW could be used from the solar PV system.

Finally, there is a rumour that Nissan may launch an uprated charger, to 6.6kW, which could be dealer installed. If that is the case then installing a 16A Home pod now might mean that you will not be able to benefit from the uprated charger without replacing your pod to a 32A one and that will mean that your £995 you spend on the 16A pod now will be wasted. This why we have gone for a 32A pod from POD Point.

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