Granny home charging instead of Type 2?

[tsedge]

I am starting to get put off in buying an MG4 or any other EV now due to all the charging hassles regarding a granny charger.
I only cover around 150km (94 miles) average weekly and was just going to charge the MG Long Range in my garage with a standard 240 volt 10 amp power source which we have here in Australia.
It would probably only need charging around 40% (24kw) once weekly but would probably need 10 hours or so which is not advised here on this forum.
I suppose the other option is to charge it for 5 hours twice weekly or after each small trip for a couple of hours or so. Perhaps this would put less stress on the home electrical system of which I obviously know nothing about?
Due to my low mileage I did not think it was worthwhile spending big bucks on a wall charger or whatever.

For peace of mind, I would always recommend a home charger. The cost is a small fraction of the cost of the EV itself and the running cost savings should pay for it quite quickly.

 

[siteguru]

For peace of mind, I would always recommend a home charger. The cost is a small fraction of the cost of the EV itself and the running cost savings should pay for it quite quickly.

Hmm. Cost of electricity is the same per kWh (except where an EV tariff is available for a compatible charge point) whether a Type 2 charge point or granny charge cable is used. 20 kWh delivered over 3 hours or 10 hours is still 34p x 20 kWh = £6.80. So how will a charge point pay for itself (vs a granny charge cable)?

Agree with the peace of mind part though.

 

[tsedge]

Hmm. Cost of electricity is the same per kWh (except where an EV tariff is available for a compatible charge point) whether a Type 2 charge point or granny charge cable is used. 20 kWh delivered over 3 hours or 10 hours is still 34p x 20 kWh = £6.80. So how will a charge point pay for itself (vs a granny charge cable)?

Agree with the peace of mind part though.

I was not comparing with granny charger, just saying EV running costs are lower than ICE and this can be used to pay for it. Edit: consider it part of the 'package' of getting an EV.

 

[Fogey]

I realise line voltage is bad enough (240V AC) but surely the in-car charger has built in protection to prevent DC battery voltage becoming live through the lead?

I have a granny charger which can supply 6, 8,10 or 13A. 6A is perfect for me as the car is on the drive much of the time during the day and I can absorb my generated solar surplus.

(my bold)

The problem is that one side of the battery (the negative side, say) will be connected to chassis, and if that isn't earthed, and the positive side is connected (via charger electronics) to line voltage - well the car body is effectively attached to line+battery voltage. Not at all good...

 

[Fogey]

Hmm. Cost of electricity is the same per kWh (except where an EV tariff is available for a compatible charge point) whether a Type 2 charge point or granny charge cable is used. 20 kWh delivered over 3 hours or 10 hours is still 34p x 20 kWh = £6.80. So how will a charge point pay for itself (vs a granny charge cable)?

Agree with the peace of mind part though.

I think the idea is that the Type 2 charge point will allow faster charging - making it easier to take full advantage of the VERY attractive (but limited, time-wise) off-peak rates available from some providers.

 

[tsedge]

I think the idea is that the Type 2 charge point will allow faster charging - making it easier to take full advantage of the VERY attractive (but limited, time-wise) off-peak rates available from some providers.

Yes, I overlooked that.

 

[siteguru]

(my bold)

The problem is that one side of the battery (the negative side, say) will be connected to chassis, and if that isn't earthed, and the positive side is connected (via charger electronics) to line voltage - well the car body is effectively attached to line+battery voltage. Not at all good...

That wouldn't happen though. (Or at least it shouldn't). If a granny charge lead can cause a live chassis then so can a Type 2 charge point - they're both connected to the same domestic consumer unit and same earth.

 

[tsedge]

That wouldn't happen though. (Or at least it shouldn't). If a granny charge lead can cause a live chassis then so can a Type 2 charge point - they're both connected to the same domestic consumer unit and same earth.

Home charge points contain circuitry to detect and instantly sever connection if there is a fault.

Edit: and this why Fogey was previously (on this or another thread) asking if anyone knew a source for that circuitry separate from the charger, so a granny charger could be used more safely.

 

[Vipar]

Hi guys it’s thicko here.?
Question. How long would it take a granny charger to charge my car so that I can do 100 miles?

 

[siteguru]

Home charge points contain circuitry to detect and instantly sever connection if there is a fault.

So do home ring main circuits?

 

[siteguru]

Hi guys it’s thicko here.?
Question. How long would it take a granny charger to charge my car so that I can do 100 miles?

It depends on what efficiency you get. Let's assume 4 miles per kWh ... to get 100 miles range you'd need to charge up by at least 25 kWh; on a granny charge lead that would take about 12-13 hours.

 

[tsedge]

So do home ring main circuits?

It isn't the same (and not all homes have a modern setup either)... some details here;

EV Charging and the PEN Fault

In February 2020 the current Electrical Regulations, also known as <a href="https://electrical.theiet.org/bs-7671/" title="">BS7671</a>, were amended to introduce some important changes relating to...

www.romatech.co.uk

 

[Fogey]

That wouldn't happen though. (Or at least it shouldn't). If a granny charge lead can cause a live chassis then so can a Type 2 charge point - they're both connected to the same domestic consumer unit and same earth.

But the point is that the charge point will (or should) be protected against loss of earth - which is half of its role.

 

[tsedge]

Hi guys it’s thicko here.?
Question. How long would it take a granny charger to charge my car so that I can do 100 miles?

Depends on how efficiently you drive. If you are getting 3.5 miles per kWh (a typical figure), you'd need 28.5kWh. A granny charger will give you roughly 2.2kW, so 28.5/2.2 = 13 hours approximately.

 

[wiz043]

It depends on what efficiency you get. Let's assume 4 miles per kWh ... to get 100 miles range you'd need to charge up by at least 25 kWh; on a granny charge lead that would take about 12-13 hours.

That makes sense. As I said earlier I only cover just under 100 miles weekly so one overnight charge weekly on a granny charger @ approx AUD$7 would probably suffice in my case.
I suppose I could break it up by topping up charge for 2 hours or so on the granny charger each time I go out?
I can see the points regarding a proper wall charger though and this is the ideal solution.

 

[siteguru]

Ah - hadn't looked at your location; just assumed you were UK.

 

[tsedge]

That makes sense. As I said earlier I only cover just under 100 miles weekly so one overnight charge weekly on a granny charger @ approx AUD$7 would probably suffice in my case.
I can see the points regarding a proper wall charger though.

I think Australia may use the MEN rather than PEN system, so requirements and safety issues may be different. Be worth checking locally with a sparky.

 

[tsedge]

Depends on how efficiently you drive. If you are getting 3.5 miles per kWh (a typical figure), you'd need 28.5kWh. A granny charger will give you roughly 2.2kW, so 28.5/2.2 = 13 hours approximately.

Apologies @siteguru missed that you had already replied.

 

[Vipar]

Better to have two answers than none thanks

 

[wiz043]

Ah - hadn't looked at your location; just assumed you were UK.

Probably similar....we have 240V and 10 to 15amp power.
Would that equate to approx 2.2kw per hour charge?
Sorry, I am a novice as far as anything electrical is concerned.