Granny home charging instead of Type 2?

[MoDolph]

Surely plugging in a 10amp granny charger pulling 2.2kw is less than plugging in a 3kw electric fire ?

It is but the problem is that instead of a couple of hours it is often 10 hours every night.

It's also usually in a garage where you can't see the plug and it's whilst you, and potentially your family, is sleeping.

 

[AndyL61]

Is the 3kW fire plugged into the ring main, or is it on its own dedicated fused spur?

It would be on the ring main, would this make a difference ?

 

[siteguru]

It would be on the ring main, would this make a difference ?

Yes ... on its own fused spur would mean no (or little) impact to other devices connected to the ring. (A 13A ring main is actually usually fused using a 32A MCB. And it's also why an electric cooker is also supplied via its own MCB from the distribution board).

 

[AndyL61]

Yes ... on its own fused spur would mean no (or little) impact to other devices connected to the ring. (A 13A ring main is actually usually fused using a 32A MCB. And it's also why an electric cooker is also supplied via its own MCB from the distribution board).

So wouldn't that be safer than the 3kw fire plugged into the ring main ? Sorry for stupid questions, electrics are a mystery to me.

 

[siteguru]

That was my point, and why I asked.

But you're right in what you originally intended ... if someone has a 3kW fire on their ring main, why should a 2.2kW granny charger be a worse thing to connect.

 

[BugEyed]

Two reasons:

• People rarely run electric fires for 10 hours at a time. FWIW most fires are 2kW or less - 3kW would be 13Amps and would overheat a BS1363 plug in less than an hour.
• Electric fires are run indoors and hence in an equipotential zone meaning that all of the Earth voltages are the same. A car is generally outside and a floating earth voltage is different to the true Earth.

 

[Lovemyev]

A cooker circuit is usually supplied from its own dedicated circuit and are usually wired with a much heavier 6mm cable, needed to carry the higher demand.
7 Kw EV wall boxes are usually wired with a 6mm cable also ( depending on the length of the cable run of course ).
High capacity / demand electric showers are supplied with a 6 mm or even a 10mm cable. Again, depending on the demand of the shower or the length of the cable run.
Emersion heaters are rated at around 2.5 to 3.00 kw’s and are also running on its own circuit as well.
2.5 mm cable usually used.
I used a Granny charger for a few months, while waiting for my wall box to be installed.
But I did NOT have it powered by a regular ring main house outlet.
I installed a dedicated RCD three pin socket outlet, wired from its own feed from in the CU.
The plug top of the Granny would still get warm to the touch, if used for a few hours.
I guess it depends on how much use you intend to give the Granny charger ?.
I you are a low usage case, then charging using a Granny at home for a couple of hours, or so maybe okay.
But if you are higher usage case and charging for many hours on a regular basis, then I would strongly suggest having a wall box installed.
If you are on a cheaper off peak tariff, then to maximise these cheaper rates.
Faster charging speeds from a wall box can allow this.
If you are at a low SOC and are charging at the slower speed of Granny, then you could find yourself not receiving the level of charge for the following morning, if you intend to use the cheaper off peak tariff.
It all depends on your usage case really.
A wall box just gives you a much faster charge than a Granny unit, and in my opinion is a safer way to charge your EV.
A quick way to work out your charging requirements, is this.
For one hour spent on a wall box, you will receive roughly about 25 miles of extra range added to your battery.
On a Granny, your talking a lot less than HALF of that figure.
Horses for course I guess !.

 

[Big Al]

No it's not the same as plugging a 3KW fire, or washing machine. Neither of these are 400v batteries, a shock from which will kill you. It's not the fact you're pulling a large current on a domestic setup, it's more to do with the earthing standards required for electric cars. Purpose built charge points, Zappi, Omni, etc provide this extra level of protection, granny chargers don't.

"For an EV charger this means that the body of the car forms the return path, presenting a real risk that anyone touching the car will get an electric shock"

EV charging equipment – The new rules explained

Myenergi's Chris Horne looks at the requirements for protection against electric shock following the loss of the PEN conductor in a TN-C-S earthed electrical system. According to HSE statistics (see T

professional-electrician.com

 

[Dan C]

Could you explain this in a bit more detail please as I have seen it mentioned before but do not understand it?

What makes plugging in the car different to say a washing machine into the same socket?

Without going into too much detail - washing machines, dishwashers, kettles etc can draw a similar amount of power to a granny charger, but these kitchen appliances only do it for a very short period of time ( your washer cycle may be 3 hours long, but it will only be drawing It’s max current for say 15mins whilst it heats up the water, the motor doesn’t use much power in the grand scheme of things )

Your granny charger is using a similar amount of power as these appliances at there peak, but for several hours or more !

 

[FiferMG4]

Without going into too much detail - washing machines, dishwashers, kettles etc can draw a similar amount of power to a granny charger, but these kitchen appliances only do it for a very short period of time ( your washer cycle may be 3 hours long, but it will only be drawing It’s max current for say 15mins whilst it heats up the water, the motor doesn’t use much power in the grand scheme of things )

Your granny charger is using a similar amount of power as these appliances at there peak, but for several hours or more !

I didn’t take such things into consideration at first and was just going to use the granny charger, but now I’m glad I’m looking into having a Zappi installed.

 

[Geoffers]

Just for balance, I have only used a granny charger since I bought the car in March. It works perfectly well for my situation and I have no intention to change. Obviously I am happy with the state of my electrics and I plug into a garage ring which doesn't usually have any other load.

If these chargers are so dangerous (1) why are they being sold/packaged with the car and (2) Why do they not carry a health warning?

 

[wiz043]

It depends on each individual situation, especially how many miles you cover.
I am now retired and only cover around 150km (94 miles) weekly, mainly urban, so a granny charger is sufficient for me as I also have solar panels and would probably only need to top the battery up once weekly.
I calculated that it would save me approx. A$1200 yearly in fuel costs over my current petrol SUV plus the extra servicing costs of around A$150 or so p.a. compared to an EV.
No doubt the savings would be a lot more with high mileage situations.
Here in Australia the same model new petrol SUV would cost me approx. the same as buying a new MG SE long range so the MG is a no brainer.
In any case I am more interested in the new technology and convenience offered in EV's in my er...'blossoming' years rather than running costs...that is just a bonus.

 

[MoDolph]

Without going into too much detail - washing machines, dishwashers, kettles etc can draw a similar amount of power to a granny charger, but these kitchen appliances only do it for a very short period of time ( your washer cycle may be 3 hours long, but it will only be drawing It’s max current for say 15mins whilst it heats up the water, the motor doesn’t use much power in the grand scheme of things )

Your granny charger is using a similar amount of power as these appliances at there peak, but for several hours or more !

That wasn't what I was asking about. I was specifically asking for more information about the earthing issue mentioned earlier.

 

[TheArcher]

I wouldn’t recommend using a granny cable for anything other than emergency charging, drawing that amount of power over such long period of time puts your wiring and sockets under a lot of stress, if you have any weak points in your wiring you could cause an electrical fire.

Invest in a proper EV charger and get on Octopus go tariff, yes it costs around £1k to get one supplied and installed, but we’ll worth it so you can use the cheap off peak rate of octopus go and charge your car safely.

I'm not sure I entirely agree. Yes, a poorly installed bit of cable to use all the time without any protection would be foolhardy. We have been charging our Smurf for 18 months on a properly wired in spur without any problems. £1k installation is an awful lot of electricity.

 

[Dan C]

I'm not sure I entirely agree. Yes, a poorly installed bit of cable to use all the time without any protection would be foolhardy. We have been charging our Smurf for 18 months on a properly wired in spur without any problems. £1k installation is an awful lot of electricity.

For me personally the proper home charger was worth it so I could fully utilise my 4 hours of cheap electricity every night ( Octopus go tariff, 4 hours x 7kw charger / car speed means I can get 28KwH of dirty cheap electric into my car per night )

Also the safety factor is priceless, I’ve seen too many burnt up sockets / cables to risk it myself. yes you might have a modern Consumer unit ( fuse box ) but none of the devices in there will detect a dodgy connection and will let it burn up ( unless you have AFDD’s fitted, which are very new to the market still )

 

[Julian Edwards]

Apologies if this has already been asked but looking for advice on a thought I’ve just had.

Is it at all viable to consider not getting a home charging unit at least to begin with and instead use granny charging overnight?

My typical daily commute is 15 miles there and 15 back so 30 in total. How long would I need to charge it with a granny lead if I wanted top up the battery?

And would it be any dearer doing it that way electricity wise because it’s charging for longer than with a proper ev charger?

Feel free to say if this is a crap idea!

There is an in-between option that is much cheaper. A granny charger is just 10amp. You can install a 16 amp socket either off an underused ring main or a 2.5mm circuit from the consumer unit. Easy and cheap to do. You can pick up a 16amp inline charger from Amazon for under £150. Make sure you get one with a 16amp plug as a square pin 13amp can only sustain 10amps.

 

[John11000]

Surely plugging in a 10amp granny charger pulling 2.2kw is less than plugging in a 3kw electric fire ?

I have seen many 13A sockets with burned and blackened pins over the years. Often where 3 bar electric fires have been plugged in.
If you use a Granny charging cable, check the temperature of the 13A plug regularly during charging and make sure it is not hot to touch. It will get warm after a few minutes.
The manual recommends that a socket used for charging is changed every 2 years.
Using an extension lead increases the chance of overheating and electrical fire.

 

[GeoffJ]

I missed out on the Government Grant for a home charger, and as my local Tesco is within walking distance and had free Pod Point chargers, I decided not to have a home charger. Tesco have just increased the cost to 28p per KWh, which is cheaper than my standard tariff cost per KWh. Sainsburys are still offering free Pod Point charging (that could change), but that's about 5 miles away and is always busy so I don't know how easy it will be to find a charger that is not in use. I have solar panels which can generate about 3KWh on a good day, so I'm now using a combination of Granny charger when the sun shines and Tesco at other times.

 

[tsedge]

There is an in-between option that is much cheaper. A granny charger is just 10amp. You can install a 16 amp socket either off an underused ring main or a 2.5mm circuit from the consumer unit. Easy and cheap to do. You can pick up a 16amp inline charger from Amazon for under £150. Make sure you get one with a 16amp plug as a square pin 13amp can only sustain 10amps.

It is possible to do things cheaply. But given the risks and the many reports out there of burned sockets and fried circuits, this is not an area I would save money on.

If you can afford a brand new EV, you can afford a proper certified charger installation.

 

[Jto]

That’s the thing. I’m not currently on an off peak tariff. Although it is something I am thinking of switching to.

Another question then, I have a 16A (I think) commando socket in my garage specifically for a fancy high powered pressure washer I used to have. Could this be utilised with an Ohme commando cable and would it be better than a granny charger?

Hi
I would get a electrician to come and check this socket out to whatever rate the main board breaker has on it and the size of the wire used. He would the best person to advise you what this rate you can use on this socket, if luck is on you side it may be a change on breaker to 32amp then you could use the Ohme.