Powering the home from spare EV charge?

Discussion about EV/Battery charging infrastructure, Electric highways etc.
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HuffnPuff
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Powering the home from spare EV charge?

Post by HuffnPuff » Fri, 20 Apr 2018, 07:01

I haven't got an EV yet, I plan to build one though. One way of speeding the approval process from the Minister for Recreation and Finance might be if I can sell it on saving electricity costs. I could even purchase the batteries and get the home grid thing going while building the car.

I wondered what the implications of using the EV as a battery storage system for the house would be. My commute is short, and I often cycle to work. Having an EV in the garage would be a better investment if when it is at home that the excess charge could be used to power the house. I envisage that perhaps the EV would charge overnight (maybe range 100km) drive to and from work (20km) then in the evenings the EV is plugged into the 'battery' port on our solar inverter and used to supplement the grid for peak hour, to a suitable level of discharge. Then, probably on timer, charge the EV back up after bed time ready for the day ahead. Rinse, repeat. In the event the car is out for the evening, the grid takes over and we aren't home using much power anyway. If I was planning to go out, just not connect the EV to the inverter to ensure there is enough range in the EV. My solar inverter is right next to where the front of the vehicle would park in the garage.

It would seem a better use of a battery storage system. There must be pitfalls to this idea. Are home batteries different to EV batteries? Could it be done with one cable to the EV? Not that using two would be a major hassle. Our solar inverter is 'battery ready'. I also have a brother working in the solar world that can help out as, while I understand the principles and am mechanically savvy, I'm not clued up on details yet.

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jonescg
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Re: Powering the home from spare EV charge?

Post by jonescg » Fri, 20 Apr 2018, 09:01

If you plan on building an EV, you can plan your home storage battery as well. Yes, the two batteries can (and probably should) differ - EV batteries are generally rated to high power discharge, while home storage cells are less powerful (and therefore cheaper).

If the battery of the vehicle is between 120 V DC and 370 V DC, you can power any PFC-battery charger through the AC input. So say the home storage is 48 V DC and it has a battery charger connected to it, simply supply the AC input of the battery charger with the DC of the car's battery. It will proceed to charge the home battery. It's potentially quite useful, especially if you seek out free charging points around town :D
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Richo
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Re: Powering the home from spare EV charge?

Post by Richo » Fri, 20 Apr 2018, 11:40

I was under the impression the only batteries would be in the car.
So no dedicated home storage.
The ev powers the house during peak times.
The grid charges the ev during off peak.

You could probably do it with one cable.
But have 2 connection points on the house.
One for charging the other for supplying.
It really depends if there is something smart enough to account for time of use(peak) to combine the two into one.
There probably is but I have specifically looked for one.

You don't get value for money if most of the capacity is never used.
This is where the life of the battery is important.
Lest say the batteries last 10 years.
You pay $10k for batteries.
20km per day is 73,000km over 10 years. $0.14/km
But if you drive 100km per day that's 365,000km $0.03/km

So it makes sense if you have a big pack to use it - even if its used on the house.
Common sense would have said get a smaller pack to start with...

How bout a short range pack on the car say 30-40km.
then 60-70km worth on a range extender trailer.
The trailer is left home 99% of the time plugged in and doing what you want.
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HuffnPuff
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Re: Powering the home from spare EV charge?

Post by HuffnPuff » Fri, 20 Apr 2018, 11:47

Thanks Gents. Yes, would consider only having one battery pack - with wheels and seats. 100km range would be better suited for weekend or day off travels, running errands and such runs up the kms. I can't see much joy in having to hook up a trailer to run the weekend errands.

A 'normal' commute day would probably be 20-30km, ie to work, home via bunnings/jaycar/coles or off to kids sport. My current ute uses about 1 tank per month, 600km, not far off 20km/day. When I put 2 and 2 together initially I was surprised that a 20kWh pack is not unusual in a car, and that our house uses somewhere near that which got me to thinking about the spare capacity and how to use it for the 'normal' commute model.

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Re: Powering the home from spare EV charge?

Post by bladecar » Sat, 21 Apr 2018, 14:57

HR,
Would you be related to PuffnStuff.

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Re: Powering the home from spare EV charge?

Post by bladecar » Sat, 21 Apr 2018, 15:06

HuffnPuff wrote:
Fri, 20 Apr 2018, 07:01
I haven't got an EV yet, I plan to build one though. One way of speeding the approval process from the Minister for Recreation and Finance might be if I can sell it on saving electricity costs. I could even purchase the batteries and get the home grid thing going while building the car.

It would seem a better use of a battery storage system. There must be pitfalls to this idea. Are home batteries different to EV batteries? Could it be done with one cable to the EV? Not that using two would be a major hassle. Our solar inverter is 'battery ready'. I also have a brother working in the solar world that can help out as, while I understand the principles and am mechanically savvy, I'm not clued up on details yet.
HR,

Just a point. If you lived in Queensland and were receiving payment for you solar power, you cannot have a home battery system without losing the solar income. I half went into it. They really don't like us. Greg

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Re: Powering the home from spare EV charge?

Post by praxidice » Thu, 24 May 2018, 05:20

That isn't totally correct. Its more a question of not being able to charge batteries at off-peak rates and sell beck to the grid at peak rates.Power companies believe they have the sole right to profiteer on electricity. If you have both grid and off-grid systems configured that there is no possibility of sending battery power to the grid, then neither Ergon nor Energex have any problem with batteries even if you are still getting the 54.6 feed-in tariff. Mind you there probably aren't many folk with both grid and off-grid systems running side by side, although the modern hybrid grid inverters would be able to charge batteries as well as export surplus PV electrons to the grid. Those setups wouldn't attract much in the way of feed-in tariff though.

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