Using a 3 pin 'emergency' charger

[Gomev]

Quite practical depending on your daily needs. Look at the power input accepted by the car and work out what that means in kWh added per hour and how long you need to leave it on charge overnight - or longer (starting after getting home from work?) to cover your daily need. So if you need to cover 100 miles in a day and your efficiency is 3 miles per kWh (which is pessimistic) you would need to add 34 kWh to cover it. If the granny charger is giving 3kW power input that would need 11 hours or so. 50 miles daily would need 6 hours etc.

Granny is only c. 2.3 kWh

 

[Harry]

Granny is only c. 2.3 kWh

Interesting - I wonder why. Anyway the point is the same with whatever numbers actually apply.

 

[djenson]

Interesting - I wonder why. Anyway the point is the same with whatever numbers actually apply.

Because that's what sockets are continuously rated for. Pulling 3kw for a long time will cause them to melt, so its reserved for "bursty" applications such as kettles

 

[Harry]

Because that's what sockets are continuously rated for. Pulling 3kw for a long time will cause them to melt, so its reserved for "bursty" applications such as kettles

What about electric fires - 3 bars, each 1kW and often left on for quite some time? It's not about the wattage its about the current drawn. I guess the granny chargers limit the wattage to keep the current below a safe threshold. A kettle draws 3000/240 amps - 12.5 amps and our domestic circuits are rated at 13 amps. Clearly car charging circuits are capable of drawing much higher currents. So I think I have answered my own question.

 

[C6MFC]

Another tip not mentioned (I think) if its a reel extension do not use with cable on the reel as heat could be generated. I always carried an extension and the granny charger in the car when traveling as in an emergency when hotel or local rapid chargers not available I parked near an accessible plug and got an overnight boost. That has happened twice when Hotel chargers not working.

 

[fatboyfat1981]

@Harry dedicated charging circuits are capable of >13A, however using the granny on a domestic circuit will depend on what else is connected to that ring & what the total capacity on that circuit is

 

[djenson]

What about electric fires - 3 bars, each 1kW and often left on for quite some time? It's not about the wattage its about the current drawn. I guess the granny chargers limit the wattage to keep the current below a safe threshold. A kettle draws 3000/240 amps - 12.5 amps and our domestic circuits are rated at 13 amps. Clearly car charging circuits are capable of drawing much higher currents. So I think I have answered my own question.

Your electric fire is going to consume the same amount of current as that kettle. That's why the 3kw electric heaters melt sockets, quite frequently. See some examples attached. That's just after looking at the first 3kw heater that appeared on amazon UK.

Another consideration is that wiring isn't going to be up to spec in some homes, Drawing 3kw might just push the already degraded wiring over the edge.

2200w will draw at most 10 amps on a 220v grid, Giving 3 amps of headroom.

Car manufacturers don't want "My car burnt down my house while it was charging" in the headlines.

 

[Harry]

Your electric fire is going to consume the same amount of current as that kettle. That's why the 3kw electric heaters melt sockets, quite frequently. See some examples attached. That's just after looking at the first 3kw heater that appeared on amazon UK.

Another consideration is that wiring isn't going to be up to spec in some homes, Drawing 3kw might just push the already degraded wiring over the edge.

2200w will draw at most 10 amps on a 220v grid, Giving 3 amps of headroom.

Car manufacturers don't want "My car burnt down my house while it was charging" in the headlines.

There's no accounting for poor equipment and poor wiring.

 

[fatboyfat1981]

There's no accounting for poor equipment and poor wiring.

Because we’ve all got £3k spare to use on getting the house rewired just to use a granny charger at 13A rather than £600-£1000 for a proper EV charger

 

[Harry]

Because we’ve all got £3k spare to use on getting the house rewired just to use a granny charger at 13A rather than £600-£1000 for a proper EV charger

How are you finding your Trophy Connect? I'm still waiting.

 

[Hairyfool]

There's no accounting for poor equipment and poor wiring.

Which is why domestic wiring installation has been subject to stringent controls for many years, even more so recently.

I would agree that the advice associated with high power devices is somewhat lax, there was absolutely nothing associated with either "granny" charger that I have had about precautions over prolonged use. It must be remembered that the majority of drivers will not use sites such as this.

Even a recent Which article on home charging only comments on the time of charge required and the trip hazard, absolutely nothing about electrical safety.

 

[fatboyfat1981]

How are you finding your Trophy Connect? I'm still waiting.

If by “finding” you mean monthly phone calls to my leasing company & the supplying dealership, checking Bristol port arrivals & AIS trackers & the occasional prayer, doing fine thanks.

Not arrived yet, expected end of June.

I do however have a MG5 works pool car to occasionally play with.

 

[fatboyfat1981]

Which is why domestic wiring installation has been subject to stringent controls for many years, even more so recently.

I would agree that the advice associated with high power devices is somewhat lax, there was absolutely nothing associated with either "granny" charger that I have had about precautions over prolonged use. It must be remembered that the majority of drivers will not use sites such as this.

Even a recent Which article on home charging only comments on the time of charge required and the trip hazard, absolutely nothing about electrical safety.

Planning on buying something like this (#notsponsored) COBA Europe CablePro GP1 Medium Duty Cable Cover 3m Black / Yellow for the charging cable, don’t want to be responsible for the postie/Amazon man/etc going base over apex

 

[Siatbury]

In the first two weeks, I have found the 3 pin to work OK, overnight sets us up for the journeys we do most days. I realise now that current wisdom suggests slow is better than fast and the battery if it could choose, would say "stay away from big fast chargers and only top me up to 80% if you want me to last a long time!"

 

[Siatbury]

Quite practical depending on your daily needs. Look at the power input accepted by the car and work out what that means in kWh added per hour and how long you need to leave it on charge overnight - or longer (starting after getting home from work?) to cover your daily need. So if you need to cover 100 miles in a day and your efficiency is 3 miles per kWh (which is pessimistic) you would need to add 34 kWh to cover it. If the granny charger is giving 3kW power input that would need 11 hours or so. 50 miles daily would need 6 hours etc.

Hi there,
So I agree now- it works fine and the granny charger gets warm towards the end, but no way hot so I can't see it as a safety issue although there is some concern in that area? I will get a faster charger but because my garage is over 50 metres from the house it is going to be SO expensive with ground works etc... maybe not worth spending £3000 to save a few hours and the EV rate for Bulb penalises daytime use by about 7 p a Kwh- what a con; no wonder they went bust!

 

[djenson]

Hi there,
So I agree now- it works fine and the granny charger gets warm towards the end, but no way hot so I can't see it as a safety issue although there is some concern in that area? I will get a faster charger but because my garage is over 50 metres from the house it is going to be SO expensive with ground works etc... maybe not worth spending £3000 to save a few hours and the EV rate for Bulb penalises daytime use by about 7 p a Kwh- what a con; no wonder they went bust!

I agree, i'm getting a few electrical compantants (namely a SPD and a type A RCD, please have these if you intend on using the granny long-term) and plan on using the granny as my main charger.

 

[charlie bravo]

Hi l got a Ohme cable though Octopus energy with 3pin plug, we do about 200 miles per week, with Octopus EV tariff charging 12.40 to 4.30 give me 32 miles for 48 pence at present, but will be going up October, very happy at moment

 

[Lovemyev]

I used a “Granny” charger for a few months while deciding on if I should invest in a wall box.
Which I did go ahead with way back in 2016.
The socket used for “Granny” was on its own dedicated circuit and a very short cable run of only about 6 - 8 feet in total.
After a full charge, the top of the 13 Amp plug on the Granny would get warm, not hot, but warm especially on the live pin area that carried the 13 Amp protection fuse.
The top of the wall box also gets warm at the top of the unit, when it is conducting a long charge cycle.
So, in this respect the heat generated is about the same.
Warm, but not mad hot !.
The thing to consider here with using “Granny” units on a older domestic supply, is that when these older houses where built, nobody ever imagined back then, that we where going to be driving electric cars and even less, that we would be demanding such high loans to charge them !.
Today, some modern electrical items demand higher loads than the electrical systems where designed to take.
Older systems running on tumble dryers / electric showers etc etc where unheard of.
The main cut out fuse ( owned by the DNO ) is a good indication of how things have changed over the years.
Our house and the surrounding properties where built in the early 80’s.
They are all running on a 60 Amp main cut out fuses.
Back then, this was seen as plenty big enough for the level of demand placed on the system.
Now all new builds get a 100Amp cut out as standard.
This displays just how times have changed in that fairly short time frame.

 

[DON]

Have not got my car yet been let down by charger installers, now i intend to run a 6mm T&E to outside and get a sparky to install a good outside socket under a bay window which is out of the rain etc, then to connect to a spare 40amp Type B MCB in CU, and use my granny charger when the car comes, then if i change to a 7kw charger the cable will be already installed any thoughts.

 

[Jomarkh]

The cable should be ok but you may need an RCBO in your CU or even a separate mini CU with O-pen protection