Should we get more home battery capacity?

[Everest]

That sounds like a great idea, but there is no reason why you couldn't also plug in the 48 V DC battery charger to the same circuit and top up the house battery from the EV's V2L output when there is no mains power, so the devices powered from the battery can be kept powered up as well.

I agree, but there could be a caveat in that as Rolfe's installer said it is not possible it could be that Rolfe's system uses HV batteries, rather than standard 15S or 16S "nominal 48V" low voltage system. As far as I can see, Givenergy have both LV and HV systems

 

[Bam Bam]

I think the whole taxation thing is indicative of just how broke the country is, equivalent to searching down the back of the sofa for loose change.

A different perspective is that it isn't a good idea to have 'loopholes.' If you can make money from solar tax free but not from other sources then this will give people an incentive to invest in solar and not in other things.

Hmmmm, doesn't sound so bad actually. Could be a 'good distortion.'

But at any rate, the general idea is to avoid these sorts of distortions.

Governments do not live up to this ideal, creating all sorts of little loopholes that become big loopholes.

I agree, but there could be a caveat in that as Rolfe's installer said it is not possible it could be that Rolfe's system uses HV batteries, rather than standard 15S or 16S "nominal 48V" low voltage system. As far as I can see, Givenergy have both LV and HV systems

I believe the hybrid system that both Rolfe and I have is 48V. The battery seems to go up to 54V.

 

[Everest]

I believe the hybrid system that both Rolfe and I have is 48V. The battery seems to go up to 54V.

Then it should be possible. Just her installer CBA. And @Rolfe.. I didn't mean a cat bite abscess

 

[Bam Bam]

The idea wasn't to connect to the EV DC circuit, but rather, a 48 V DC battery charger being powered by the V2L and the output from the battery charger connected to the battery at the end of that cable with the two ring terminals (at least that is what they look like) by adding ring terminals with the same size bolt hole to the 48 V DC battery charger outlet cables.

T1 Terry

Thanks for clarifying.

So something like this?
LiFePO4 Charger (Fogstar Energy) - 48V 35ADefault Title

My worry would be that a lot of time, money and effort could be spent setting all this up and the Givenergy system will just say 'no, I don't know what that connection is so I will just shut everything down"

There is a Givenergy thread on this topic for the (presumably high voltage) All in One system, though they are waiting for Givenergy to officially allow it rather than discussing these DIY jobs.

Connecting an EV with V2L to an AIO

I agree that V2G is a very interesting technology for many of us, but is frustratingly slow in coming. One thing that should be possible now is to use V2L to drive an individual load in the house, therby reducing the demand on our AIO. I have an oil boiler driving a large underfloor system...

community-beta.givenergy.cloud

 

[Everest]

So something like this?
LiFePO4 Charger (Fogstar Energy) - 48V 35ADefault Title

IMHO, no. For reasons mentioned in my posting below...
Better to have an adjustable supply, as @johnb80 mentioned - see my link in post #24. Or telecoms PSU such as Eltec Flatpack, Emerson or Chargeverter.

Post in thread 'Solar battery and V2L'

May 6, 2025

@Everest Which LifePO4 charger would you recommend

One that is adjustable with regard to output current and voltage and needs to be of a galvancially isolated design. As @wattmatters and @johnb80 have said, the Fogstar one is too much current IMHO. It is also lacking in any detail whatsoever with regard to output voltage.

As I mentioned in my post #8 you will need to consider maximum charge rate that your BMS supports and match (or adjust) the charger to not exceed that current when your inverter is running on full charge rate.

I note there are no fuses shown in...

• Everest

My worry would be that a lot of time, money and effort could be spent setting all this up and the Givenergy system will just say 'no, I don't know what that connection is so I will just shut everything down"

Provided the PSU is voltage adjustable to not exceed battery or vehicles current limit, the existence of the PSU will be invisible to the inverter, thanks to Kirchoffs Current Law

Edit; link to earlier link...

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

• 
•