60 amp house fuse and EV charging

tired_dad

Hi,
My whole house has a single 60 amp fuse. The cable supplying the house is only rated for this amount and cannot be upgraded to 100A.

I have had a quote for a 3 phase installation and all in it will set me back 5k at least.

Would I be able to have two 7kwH EV chargers put into the garage?

These are rated at 32A. Not sure if they actually draw that power.

Or is that a total no go?

grumbler

7kW, not kWh?
This looks about right for 32A
32*240=7.7

jk0

How many miles a day do you do? Most cars manage around 4 miles per kwh, so a 7 hour charge on a 3.6kw will add 100 miles.


Go with two 3.6kw IIWY. I don't think there is any point in upgrading your supply.

almillar

7kW, not kWh?

Yes kW, a measure of power (speed of charging), not kWh, a measure of stored power.

I have had a quote for a 3 phase installation and all in it will set me back 5k at least.

You'd be hard pressed to need 2x7kWh chargers. Charging 2 cars overnight, 10 hours, that would give you 140kWh of charge. At 3 miles per kWh, that would be 420 miles every day, between 2 cars! Surely that's overkill?! How much to just upgrade single phase to 100A? Seems more sensible.

Go with two 3.6kw IIWY. I don't think there is any point in upgrading your supply.

Yes, OP's situation is one of only a few where I can imagine actually spending money on a 3.6kW charger, instead of a 7.

Ectophile

Two 7kW chargers is a no go. They will draw the full power if the vehicle is below about 80% charge, and may do so for several hours.


With both going at the same time, that's about 60A just charging the cars. You'd have to sit in the dark with nothing but candles for illumination.


Do you really need two?

tired_dad

Thanks for comments to date.

UKPN confirm a 100A fuse upgrade cannot be done. Property is serviced by a 16mm 2 core cable. Was fitted in 1985. Apparently this is rated at 60 amps.

My options seem to be
1. Install 1 x 7kw charger
2. Install 2x 3.6kw chargers.
3. Go all out and pay big bucks for a 3 phase. Ultimately I think this will have to be done to heat house and charge cars when gas boilers get binned.

jk0

I've got 9.3kw of storage heating, a 3.6kw car charger & 60 Amp fuse.


The fuse won't go until you run about 50% extra current through it for hours, so I would not sweat about your installation.

tired_dad

Would 1x 3.6 and 1x 7 be crazy?

almillar

Would 1x 3.6 and 1x 7 be crazy?

You still haven't told us why you need 2 chargers. I've done calculations for you above. I assume you plan to have 2 EVs. You could very likely get away with charging them every other night.

Ectophile

tired_dad wrote: »

Would 1x 3.6 and 1x 7 be crazy?

Yes, it would. That's still about 46A out of your 60A. You would still have little electricity left to run anything else in the house. Boil a kettle and you've hit the limit, even with nothing else turned on in the house.

tired_dad

yup just planning a 2EV life. A cheap one 35KW battery and a big one 95KW battery. The latter seems to take ages to charge even on a 7kw charger let alone a 3.6 one