Granny Charging

[Johnmg5]

Hi
Newbie here
Can someone explain about using the granny charger on the MG5. I Keep seeing that it is not recommended for full time charging I was under the impression that it is far better to charge
lithium ion batteries slower rather than using fast charging
Is the main issue not the car but if the electrics or the wiring for the 3pin plug can't take the Loading or the heat etc
Plus for me the time it would take is not a issue
Cheers
John

 

[Jomarkh]

Hi,
There are a few threads on here about 'granny' EVSE.
You tend to need them on for 10-14 hours to get from 20-90% so the plug top and an old socket can get warm. They do not have earth protection. They draw about 10A 2.2kw so not good on cheap extension cables.
What sort of milage do you do?

 

[Johnmg5]

Hi
About 60 miles per week plus once every 3 week around trip of 340 miles
Cheers John

 

[Justin H]

Don't get confused between fast chargers and DC rapid chargers. A 7kW AC fast charger will not damage the batteries. It's the big 50kW+ rapid chargers that will degrade the batteries quicker.

 

[Johnmg5]

Cheers

 

[5teep]

If you intend to use the granny there's a couple of things you should check. The charger pulls a moderately high power (about 2.3kw) for a long time so make sure the socket it's plugging into is in good condition and any extension lead is heavy duty and also in good nick. The cable from the socket will get warm but should not be hot (sign of bad contacts or wrong rated cable)
I charge my car up most days using one and it's fine. The figure for charging say 18 hours!!! but remember that's from flat which you will never be. If my car is lower than say 50% I'll top up a bit on DC and then use the granny to finish the job overnight.

I do high mileage, upwards of 200 miles most days so have to charge a lot and it's handy being able to set off with 100% in the morning.

 

[5teep]

Also, a 50kw charger isn't going to damage your battery to any noticeable degree, the charging process is designed to protect the battery as much as possible. One handy rule though is not to charge past 80% on DC if you don't have to. Partly to help with battery life (which is very long anyway) and partly because you charge rate drop rapidly after 80% so it takes much longer to go that last few percent.

 

[Johnmg5]

Thank you

 

[Seaniepie]

If you use an extension, make sure it is fully uncoiled. If you need to coil it, do so in a figure of 8 which prevents it from overheating.
I use mine once a week after a charge up to 90% at a fast charger (it goes down from about 50kW/h at 80% to 35kW/h at 90%). Trickle it up to 100% from that. The granny will charge about 4% per hour on the MG5SR (which is what I have) and about 3% on the LR. I subbed off of my mains and installed a separate Garage RCD/MCB unit and run a steel wire armoured cable out to a weatherproof timed socket. Octopus Go let you get 12:30am to 4:30am at 7p/kW. The first 3hrs will get it to 100% and then the next hour or more will balance the cells. You only need to do it once a month, but doing it more often will not hurt it and keeps it tip top.

 

[DON]

I am waiting for my zs ev so have been getting quotes for a charger, so far best quote £700 after grant as i only do 4 or 5k per year started to think maybe run a 6mm twin & earth to outside and fit a socket and get a sparky to connect to cu, and just charge with a granny charger as we are on economy 7 put that on a charging forum and got slaughtered about no penn protection etc, and should by emergency use only, I still cannot see the difference with plugging in to a inside house socket which I cannot do, so I asked what would be suitable for me to plug a granny charger in to outside and did not get one response, apart from you cannot do it get a proper charger so don't know what to do, I really don't need a smart charger as the car can be charged off app.

 

[smokie]

The PEN protection is all relatively recent legislation which wasn't in place when my original EVSE was installed. So I used that for a few years with no problem - however when it broke I was easily persuaded of the benefits of it, even though I am not a heavy user.

Having said that, I doubt anyone has the required protection when using the granny socket.

Maybe there is somewhere you can find the risks, and do stuff to mitigate (like maybe not charge when it's raining).

I would have thought if you were planning on a new socket it would be better to put it on it's own circuit and breaker but I'm sure someone will be along soon who knows ore than me.

 

[DON]

The PEN protection is all relatively recent legislation which wasn't in place when my original EVSE was installed. So I used that for a few years with no problem - however when it broke I was easily persuaded of the benefits of it, even though I am not a heavy user.

Having said that, I doubt anyone has the required protection when using the granny socket.

Maybe there is somewhere you can find the risks, and do stuff to mitigate (like maybe not charge when it's raining).

I would have thought if you were planning on a new socket it would be better to put it on it's own circuit and breaker but I'm sure someone will be along soon who knows ore than me.

I agree i would even get the sparky to put it on a separate cu with breaker so not to interfere with my house cu, also the socket would be under a bay window so always dry.

 

[bwanamdevu]

I only use the Granny! The cost of an installed charger at £750 or so is just too much for the financial benefits that it gives me. Only charge using it once every two weeks or maybe more. I use a dedicated socket for power tools in the garage and the electrics are less than nine years old.
Always check the plugs, cables etc for heat generation and they never get hot, not even warm!
My electrician seems happy with the set up.

 

[Jomarkh]

If you use an extension, make sure it is fully uncoiled. If you need to coil it, do so in a figure of 8 which prevents it from overheating.
I use mine once a week after a charge up to 90% at a fast charger (it goes down from about 50kW/h at 80% to 35kW/h at 90%). Trickle it up to 100% from that. The granny will charge about 4% per hour on the MG5SR (which is what I have) and about 3% on the LR. I subbed off of my mains and installed a separate Garage RCD/MCB unit and run a steel wire armoured cable out to a weatherproof timed socket. Octopus Go let you get 12:30am to 4:30am at 7p/kW. The first 3hrs will get it to 100% and then the next hour or more will balance the cells. You only need to do it once a month, but doing it more often will not hurt it and keeps it tip top.

You can do a battery balance on a fast EVSE unit but not on a rapid one

 

[Deleted member 7171]

I am waiting for my zs ev so have been getting quotes for a charger, so far best quote £700 after grant as i only do 4 or 5k per year started to think maybe run a 6mm twin & earth to outside and fit a socket and get a sparky to connect to cu, and just charge with a granny charger as we are on economy 7 put that on a charging forum and got slaughtered about no penn protection etc, and should by emergency use only, I still cannot see the difference with plugging in to a inside house socket which I cannot do, so I asked what would be suitable for me to plug a granny charger in to outside and did not get one response, apart from you cannot do it get a proper charger so don't know what to do, I really don't need a smart charger as the car can be charged off app.

May be a 10 metre granny charger with variable output would suit you. I have one from EV one stop, see link. I don't use 13 amp as the socket gets pretty hot over time. I use 6 or 8 amp output most of the time. Got it through their Amazon shop.

GEN-2 EV Home Charging Cable | Type 2 to 3 Pin Plug

Easily charge your EV from a domestic 3 pin socket adjustable charge rate between 6, 10 and 13 amps. This is suitable for all UK households. Just plug and charge! UK BS 1363 power plug Type 2 charging plug 5/10 metre Current: 13 amp MAX with switch between 6/8/10/13 amps Voltage range: 220V ±...

evonestop.co.uk

 

[Ozzie1989]

I am waiting for my zs ev so have been getting quotes for a charger, so far best quote £700 after grant as i only do 4 or 5k per year started to think maybe run a 6mm twin & earth to outside and fit a socket and get a sparky to connect to cu, and just charge with a granny charger as we are on economy 7 put that on a charging forum and got slaughtered about no penn protection etc, and should by emergency use only, I still cannot see the difference with plugging in to a inside house socket which I cannot do, so I asked what would be suitable for me to plug a granny charger in to outside and did not get one response, apart from you cannot do it get a proper charger so don't know what to do, I really don't need a smart charger as the car can be charged off app.

Please ignore those people who clearly jumped on the bandwagon and know nothing of what they are talking about. There is nothing unsafe about using the granny as long as you do it properly, check it regularly and change any components (e.g. socket or fuse in plug) if they show any signs of damage or overheating.

The PEN fault detection is a safety feature to cover you in the unlikely (but not impossible) event that your household earth has a fault state at some point. Without it you may touch your car and become a path to earth yourself, thus suffering electrocution.

If you have an electrician fit a dedicated socket they can, depending on distance to your car, surrounding structures etc., fit an earth rod or a separate fusebox for your socket containing a PEN fault detection device. That being said I don't think I've seen one example of anyone being electrocuted without it, but it is possible and could happen one day.

All the above will be cheaper than your typical smart charger. Note you can get dumb chargers still (around £250) or as an alternative, you can have a 32a commando socket fitted and use a smart charging lead if you need a higher/faster charging rate.

 

[Seaniepie]

Please ignore those people who clearly jumped on the bandwagon and know nothing of what they are talking about. There is nothing unsafe about using the granny as long as you do it properly, check it regularly and change any components (e.g. socket or fuse in plug) if they show any signs of damage or overheating.

The PEN fault detection is a safety feature to cover you in the unlikely (but not impossible) event that your household earth has a fault state at some point. Without it you may touch your car and become a path to earth yourself, thus suffering electrocution.

If you have an electrician fit a dedicated socket they can, depending on distance to your car, surrounding structures etc., fit an earth rod or a separate fusebox for your socket containing a PEN fault detection device. That being said I don't think I've seen one example of anyone being electrocuted without it, but it is possible and could happen one day.

All the above will be cheaper than your typical smart charger. Note you can get dumb chargers still (around £250) or as an alternative, you can have a 32a commando socket fitted and use a smart charging lead if you need a higher/faster charging rate.

As an electrician, I agree with Ozzie to a certain extent. Granny chargers are used on a ‘at your own risk’ basis. It doesn’t have earth protection because, basically, it doesn’t really help to have one. The reason being that it would be connecting to your house earth and your car is probably not in your house. The time it would take for the earth current to go through the cable, around your ring circuits and to your distribution unit would be an age compared to through you and ground.
Plus you have to remember what would be needed to cause a fault enough that the body of the car would become live. It would take a catastrophic failure of the charging unit inside the car and it’s protective circuits AND the granny charger at the same time. Whilst you are touching it. For the split millisecond before your RCD detects it. The PEN or PME only add another level of protection. This extra level would be a lot more recommended for 3phase chargers, the sort required for 7kW chargers. Up to 3kW on single phase 240v, it shouldn’t be as big a risk.

The main reason they would say it is for emergency only is because the circuits used in the MG supplied unit are not up to the same standard as a mounted one and is subjected to all sorts of potential mistreatment. Cables getting bent, stressed, cut or otherwise damaged. Like a laptop power supply, if it’s well looked after it will serve you fine for many years, day in, day out. However, if you are constantly getting it in and out of its bag, folding and straightening it, you are doing ‘untold’ damage to it and risk causing a failure. But, fortunately, the device or the car will pick up on it and prevent it from working before it causes you or anyone else any harm.

If you are running a line outside and not just to a garage, I would recommend using 6mm² steel wire armoured rather than standard 6mm twin and earth. It will serve you better in the long run even though a little harder to work with.

 

[Cocijo]

If you intend to stay with an EV for many Years and have a drive/dedicated charging area at home, it is worth considering a dedicated wall box. I know that they are expensive but over many Years they are a worthwhile investment, and should really be viewed as part of the EV purchase.
Even for those with low annual mileage the quicker charging speeds and convenience of use are worthwhile. The Government grant will also not be available forever.

 

[Johnmg5]

If you use an extension, make sure it is fully uncoiled. If you need to coil it, do so in a figure of 8 which prevents it from overheating.
I use mine once a week after a charge up to 90% at a fast charger (it goes down from about 50kW/h at 80% to 35kW/h at 90%). Trickle it up to 100% from that. The granny will charge about 4% per hour on the MG5SR (which is what I have) and about 3% on the LR. I subbed off of my mains and installed a separate Garage RCD/MCB unit and run a steel wire armoured cable out to a weatherproof timed socket. Octopus Go let you get 12:30am to 4:30am at 7p/kW. The first 3hrs will get it to 100% and then the next hour or more will balance the cells. You only need to do it once a month, but doing it more often will not hurt it and keeps it tip top.

Thank you

 

[Seaniepie]

The grant runs out for installation up to 31 March. I wonder what they mean though by:

We will transition to a new digital service, details of which will be available in due course.

Are they going to set up an alternative incentive.

I don’t have a driveway so have to use the slightly illegal method of running the cable across the pathway. I do this in a low profile cable tray for safety. And only at midnight til 5am in a well lit area. The local guidance is not entirely clear in my circumstances and so have written to the council for clarification. I will continue until I’m told to stop. - I need to move!