Is it possible to totally run an EV on just a Granny charger? 🤔

[GaryMG4]

When I did a 10 hour test on the granny charger to check it was ok to run for that long it added 83 miles and the plug,lead and socket were fine. Its currently on charge, smart plug is showing a consistent 2235w, the car (app) fluctuates between 1.9 and 2.0 kw, and the smart meter is showing consumption from grid between 0 and 300w from grid, the rest is sunshine.

 

[Rolfe]

I think you're getting a little more than I get - my app consistently says 1.87 Kw going into the car, and I've calculated about 7 miles per hour being added to the battery. I did a run of 26 hours (following the recommendation to charge up from <10% on a slow charger every 3-6 months) and everything was hunky-dory. I checked the plug and socket at 24 hours and they were cold.

 

[Paul Mason]

I have a 2021 MG5 SR, now with 42k on the clock. I generally charge with a 7kW charger at home. When in France the rapid charger near my Airbnb didn't work so I used the granny charger for the first time, using a Toughleads adaptor. Worked fine an remained cool. I used it three nights for about 10-12 hours overnight. Surprisingly got between 30% and 50% added each time. Happy with that

 

[GaryMG4]

I think you're getting a little more than I get - my app consistently says 1.87 Kw going into the car, and I've calculated about 7 miles per hour being added to the battery.

I expect its a combination of different BMS for the LFP battery and I live in the flatlands of Norfolk and the gom bases the mileage added on my 4-4.5 mile per kWh.

 

[mst33594]

I average about 900 miles a month but my average daily is only about 30-40 miles now I work from home a few days a week. I’m on Octopus Go so four hrs cheap. I’ve only had to charge outside of the cheap hrs once in 6 months as I was down to 60 miles left. At 28p per unit comparable commercially available charge point.
Can be done if you’re not doing high miles per day and can build range back up during a week

 

[Soaraway]

I'm getting 2kw granny, so 6kwh per night for the three hours I charge. I use a timer on the 3 pin as MG4 charge management is a bit pants.

Sufficient for our needs so I'm not intending to buy any fast charge points for home.

 

[Gadget Geek]

I'm getting 2kw granny, so 6kwh per night for the three hours I charge. I use a timer on the 3 pin as MG4 charge management is a bit pants.

Sufficient for our needs so I'm not intending to buy any fast charge points for home.

Switching off 2kW at the plug could cause a voltage spike which could possibly damage the electronics. Always best to let the car switch on and off with the 12V Pilot Signal.

 

[google1901]

Whether to install 7kw charger (& cheap night tariff) vs granny charger (normal Kw p/hour rate). But other info is surely need e.g. kw usage for domestic needs. Our mileage is low (MG5 fl) so overnight charge every 7-10days yet domestic Kw usage in same period is greater. In effect I can't justify a 7kw charger + cheap overnight rate as the (octopus) daily rate higher henc domestic Kw usage would be more expensive. At what point do these number swing the other way? Keep checking the maths!

 

[littleflower]

Don't you get more for selling your solar excess and charging the car overnight on the cheap tariff?
If you get 1% an hour how do you get 16% in 7 hours?

No. They make money on the electricity they buy unless you have one of the special deals that were available in the green deal days. We charge in the morning and then fill the house battery before we export

 

[gwig66]

I granny charge my MG ZS EV day to day on an outdoor power socket straight off the mains supply (I did use an electrician!) and get 20% battery charge in 4 hours. I know the rapid chargers nearest to home if I get caught out needing a full charge for a spontaneous journey.
N.B I have found since the weather changed my range is significantly lower. 50% reduction when I had to keep the hot air going for misty windows on the motorway. That was a spontaneous charge at a Pod Point occasion.

 

[Exdro]

I’m confused I thought a granny charger charged a 1 kw approx 3.5 miles an hour so that’s about 42 miles a day charge
How many miles a day do you would think you would use ?if Under 40 a grannie charger would just work if more I think you would be struggling

Granny charger (usual caveats about electrical safety apply) will charge at up to 3kw per hour. At a realistic 2.5-4 miles per kWh will give minimum of 5 up to 12 miles per hour charge time.
Over the summer I used granny charger from solar panels and rarely needed to use the 7kwh charger. Therefore perfectly feasible to charge 7 hours per day on granny, giving between 35 to over 80 miles per day depending on outside temperature and driving style.

 

[philip456]

I'm using a 3kWh public charger.

It consistantly charges my ZS long range at 5% an hour, which is fine for me.

 

[Mo45563]

As I've said in another thread I'm considering getting an X power. Is it possible to just use the supplied Granny charger to run the car. As I won't be venturing to far from home. For say, at least a couple of months, to find out if I really like an EV/X power and can live with it permanently, rather than go to the expense of a home charger, and then find out I hate it, (doubtful but you never know)

Theirs is no “granny” in it. It’s a charger. It works same as any other. Only difference is speed. If anything it puts less wear and tear on the battery by charging slower.

If you have your own home location to charge at, and your able to charge at your leisure based on your patter of usage, and, it’s a no brainer to just use that and at occasional other times go to a fast charger.

 

[Rolfe]

As I said, I'm absolutely fine with my granny charger. Last charged Sunday night/Monday morning, car still at 81%, and I'll probably not charge again until Tuesday of next week, because I have a long run on Wednesday.

If I get back quite low on Wednesday evening, which is likely - possibly under 40% - I'll just plug in and let it run, as I'm not needing the car on Thursday. In the unlikely event of needing it full by Thursday, I could just give it 45 min on the public rapid charger five minutes walk away then take it home to complete the charge and balance on the granny during the night. (Of course this is helped by that charger only costing 30p per unit.)

If I change, and I very well might, it will be for economy. I was watching the podcast a couple of weeks ago, and was quite struck by the possibilities of a full home system of variable tariff, home battery and solar. My next door neighbour in an identical house has this and has been telling me all about it. He says, as the podcast emphasised, that all three together work in synergy so that you seldom use any peak-price electricity at all. He believes his system will pay for itself in four years. Our houses have a rather vast expanse of south-facing roof, so I've known for years it's the sensible move, I was mainly concerned about the payback period.

But I absolutely don't have to do this in order to keep the car on the road. The granny charger does all I need, and if the public charger price went up a lot I could manage that I rarely used it.

(Small tear in my eye there, seeing Prospero, my late lamented Golf GTi Mk6, sitting in his place on the driveway in the current Google Streetview image, a place which is now occupied by Caliban.)

 

[Exdro]

As I said, I'm absolutely fine with my granny charger. Last charged Sunday night/Monday morning, car still at 81%, and I'll probably not charge again until Tuesday of next week, because I have a long run on Wednesday.

If I get back quite low on Wednesday evening, which is likely - possibly under 40% - I'll just plug in and let it run, as I'm not needing the car on Thursday. In the unlikely event of needing it full by Thursday, I could just give it 45 min on the public rapid charger five minutes walk away then take it home to complete the charge and balance on the granny during the night. (Of course this is helped by that charger only costing 30p per unit.)

If I change, and I very well might, it will be for economy. I was watching the podcast a couple of weeks ago, and was quite struck by the possibilities of a full home system of variable tariff, home battery and solar. My next door neighbour in an identical house has this and has been telling me all about it. He says, as the podcast emphasised, that all three together work in synergy so that you seldom use any peak-price electricity at all. He believes his system will pay for itself in four years. Our houses have a rather vast expanse of south-facing roof, so I've known for years it's the sensible move, I was mainly concerned about the payback period.

View attachment 21016

But I absolutely don't have to do this in order to keep the car on the road. The granny charger does all I need, and if the public charger price went up a lot I could manage that I rarely used it.

Never mind the payback time. If you reckon that a £12k system of panels and battery will give you about £1500.00 of electricity each year. Where else can you get a 10% + return tax free almost guaranteed for 25 years?
As electricity prices rise, the return gets larger and the payback time gets shorter.

 

[Rolfe]

I haven't done the sums, but Nick next door has, very competently, and he's convinced. Since the two houses are identical (mirror-images) I'm inclined just to ask him who is supplier is and get them to duplicate the installation.

 

[Handyman Cliff]

I plan to get a 7kw charger fitted but have exclusively charged my MG4 Trophy at home with the granny lead direct to a plug next to my consumer unit.

I can charge from 20% to 80% in 17 hours approx

I do low local mileage generally and have a different work vehicle so no issues at all for me just using the granny.

I do plan to fit a 7kw charger but primarily to make it easier to plug in at the front of my house which will just be simpler for me.

 

[MG steve]

I can charge at work if there’s excess solar so summer only. In the winter I charge at home on the granny charger set to 6A for 7 hours. It’ll put in around 15 miles more than I’ll use for the day. The car has sufficient range for the weekend then it tops up all week. If we need longer range I’ll leave it on charge for longer.

 

[Speedy Baz]

Mmm. Have you checked your app? Because there are losses in there and what your smart meter is charging you for may not be what the car is getting. My car usually charges at 1.87 Kw on the granny charger according to the app.

There are losses correct, especially if you use an extension lead, the voltage drop across the lead and plugs cause heat, so keep plug pins really clean, and plug charger in as close to socket as possible.

 

[Fogey]

There are safety issues with granny chargers:

The UK earthing system is vulnerable to the loss of Neutral connection off-site. In this country, Neutral is earthed at the local substation, and that forms local Protective Earth, and if there's a break in the Neutral line to your premises, your entire premises will float up to line voltage. Which is OK if you and your appliances are entirely contained within your premises - but not if you're charging an EV parked on your driveway. So, in the unlikely event of a Neutral line breakage, a potentially lethal situation may arise...

And, as already mentioned, house wiring may be inadequate to support prolonged current draw when charging an EV (even at 6A) - in which case there's a potential fire risk.