Home Forums Chat Forum Using an electric car as battery storage?

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  • Using an electric car as battery storage?
  • gobuchul
    Free Member

    Looking at making the best out of my solar panels and I thinking of buying an electric car,

    I have heard of people using an electric car as battery storage but I have tried to google it and can’t find anything on the interweb.

    Looking for a system that would charge the car during the day, then run the house off the battery at night, down to a preset power level, so you could have a minimum range remaining in the morning. Most of our journeys are short and we don’t use the car everyday.

    Does such a thing exist?

    molgrips
    Free Member

    I think it was mooted as a concept, rather than something you could actually do with current electric cars.

    IHN
    Full Member

    From what I’ve read, it’s the future of electrical usage and storage, there must be kits available

    wwaswas
    Full Member

    There’s a twitter user called @IronMillHydro who’s up on this – a tweet at him would probably give you an answer.

    winston
    Free Member

    Its called vehicle to grid and was something Nissan promised would be available for the Leaf and then never delivered.

    mikewsmith
    Free Member

    Tesla Power Wall by using the older batteries as home storage rather than charging and draining the car battery more often?

    wwaswas
    Full Member

    You can also buy a Leaf battery pack for £2.5k

    riddoch
    Full Member

    I have a former work colleague who is buying a tesla for this very purpose. Not sure how much is off the shelf and how much he is building himself to allow his panels to use the cars battery as storage.

    simon_g
    Full Member

    Lots of concepts, nothing available off the shelf to buy yet afaik.

    Battery storage (on a battery separate to the car) you can do right now but depending on your feed-in tariff it may not make financial sense to do so.

    stevextc
    Free Member

    Tesla Power Wall by using the older batteries as home storage rather than charging and draining the car battery more often?

    There is a reason they use older batteries…

    mikewsmith
    Free Member

    There is a reason they use older batteries…

    Yes, because the demands on car and home use are very different and yes it is because as batteries deteriorate they are worse in the cars. It’s a good recycle/reuse process.

    zippykona
    Full Member

    These “old” batteries ,  how big are they and what do they cost?

    sharkbait
    Free Member

    A mooch around on here will give you some info…

    https://www.navitron.org.uk/forum/index.php?board=30.0

    Daffy
    Full Member

    From what I understand the OP isn’t trying to connect an electric car to his house to feed energy back into the grid, he’s talking about buying an EV battery and storing energy from panels in the car battery, which means you’d need a way to replicate the cars charging system in your own home.

    I thought about doing this too, but couldn’t find any way of getting it signed off even if you did get it installed.

    As a comparison to a Tesla PowerWall which has 13.5kWh for the latest model and costs £7k inc vat.  U BMW I3 batterypack from ebay will cost £3k and has 24kWh.  The other problem is size and weight…the BMW pack is 180kg.

    shadthebad
    Free Member

    This may be suitable for you.  It’s a smart charger and decides what to do with your solar generation and how to power what from where.

    https://myenergi.uk/product/zappi/

    There’s even a video https://www.youtube.com/watch?v=0EtegQfZQRw&t=25s

    Don’t forget to check if there’s a government grant available too.

    maxtorque
    Full Member

    No EV currently in production offers V2G (Vehicle to Grid) as yet.

    The onboard AC EVSE charger is not bi-directional and can only sink power from your house AC supply and cannot source it back again.  Therefore to achieve this you will need access to the HVDC link and will need a suitable inverter to create a 50Hz sine wave from the vehicles (variable voltage depending on State of Charge (SoC) battery).  The problem with this is that all EV’s disconnect their HV battery when turned off (for safety) and if you short cut the system at take out power when the car is “turned off” then that power will not be counted by the Battery Management System and hence it will report an incorrect SoC, leading to all sorts of knightmare-ish problems!

    Far better, as suggested, to buy a secondhand battery pack, unless you have a really massive solar array then actually you don’t need that much capacity, and use an off-the-shelf solar inverter to generate the AC output.  The biggest issue is how to integrate that AC feed into your current grid fed AC feed.  Current rules require standalone  inverters etc to turn off on a loss of grid voltage in order to protect line workers etc from back feeding making parts of the system un-expectidly live.  One option would be to install a second AC ring main in your house, for certain high consumption items (like washing machines etc) or to run say the lighting off the system (low load but long hours).  That inverter could also be programmed to try to minimise incoming current from the grid supply (ie measure current at your incomer, and increase it’s output to try to get that incoming current to zero)

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