Should we get more home battery capacity?

[T1 Terry]

My own thoughts about a prolonged power cut are that although I can't seem to get the power from the car into my home battery, I could run an extension lead from the car directly into the house for most usage, and save the solar - going into the home battery - to run the central heating boiler, which can't be run directly from the car. This might not work in very dull weather in the middle of winter, but most days I get enough solar for it to work.

How much power does the central heating draw? Is your house battery 48vdc?

T1 Terry

 

[GaryMG4]

How much power does the central heating draw? Is your house battery 48vdc?

T1 Terry

Our oil boiler draws 100-150w when running, I suspect it may be an earthing issue.

 

[Rolfe]

The boiler draws about the same as Gary's does, I reckon. However it's hard-wired into the circuit and can't be plugged in to the VtL. I have an emergency power supply setup where, if the power goes off, the boiler continues to run from the home battery, and there is also a double power point in the fuse cupboard which also draws from the battery. This should be fine short-term so long as the battery isn't too low when the power cut happens.

The 9.5 kwh battery will fill up during the day from the solar, so in the summer it should be capable of powering the house indefinitely. However in winter if it's very dull there isn't enough solar to do that. At that point the extension lead from the car would substitute for the power point in the house, and all the battery (solar) would go to keeping the heat on.

Trip-hazard central, but it would work. Run the wifi all the time, TV, radio, computer, a table lamp or two as necessary, kettle, toaster and microwave for cooking. (I also have a one-ring portable induction hob.) Overnight plug in the fridge and freezer. The solar should at least keep the boiler going, whatever more, and if the car was getting low I could drive to somewhere with power and charge it. If the entire country for 50 miles in each direction is out for a prolonged period, we have more problems than just me.

 

[Everest]

The solution that I and others (e.g. @johnb80) have detailed on other threads - assuming you have standard low-voltage (nominal 48V) system is to charge / top up your home storage batteries via an adjustable telecoms-type power supply from V2L output of the MG. e.g. as discussed in the thread below. This decouples the vehicle from the house supply saving you having to add any extra wiring, earthing, RCD's etc.

Post in thread 'Connecting a V2L car to a house as a battery.'

Dec 2, 2025

Hi John. This sounds exactly like the setup I'm after. I haven't been able to find anyone that's actually tried this yet, so this is quite exciting. When you say 'feeding onto the wires', how have you done the connection? Paul

Hi Paul,
I connected to my DIY battery directly onto the DC wires (big black and big red) that go from the inverter to the battery. At this point the 48v DC is being fed into the inverter via the BMS (Battery Management System all batteries have). It's very easy to do and you could just purchase an extra battery cable if it's a commercial battery you have or...

• johnb80

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[Rolfe]

Would that that were possible.