EMC
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Joined: Tue Aug 01, 2017 3:01 pm

Bolt as a Powerwall

Thu Aug 03, 2017 3:02 pm

Has anyone thought of using the Bolt as a powerwall when you are not driving? I would think for a retired family using the 60 KW to store the excess from solar or off peak hours looks interesting. A car is only used 5% out of the day. Whay not use it for more than transportation.

If you had a small reserve battery to run the house when you are using the Bolt when away.
I think the Japanese are starting to do this.

I wonder how the battery would holdup for this use.

My 16 KW iMiev might have a second life as a powerwall at the house. I paid less than 1/2 of what a new 16 KW battery would cost.

I would think that a solar household with 2 ev's would never need the grid or use it very little.

PV1
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Re: Bolt as a Powerwall

Thu Aug 03, 2017 3:27 pm

V2G is one of the things that get talked about endlessly, but I'm not sure we'll ever see it in the US.

Mitsubishi's M-tech Labo has a rather neat setup of wind, solar, stationary, 2nd life EV batteries, and a fleet of i-MiEVs. The system favors the stationary batteries to try and keep the cars charged, but it will use the car batteries when needed. A condensed setup like this would be perfect for a house. I envision that you specify a set charge level that you want the car to always maintain (say 50% charge) and the system will freely use the capacity above this setpoint when the stationary battery isn't enough. You may leave the house with more range than you programmed, but not less, at least if you don't override it to keep the lights on :? .

The stationary battery wouldn't need to be that big with a Bolt plugged in. Maybe an old i-MiEV or Smart ED pack would work well (or two EVs where only one is driven at a time).
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oilerlord
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Re: Bolt as a Powerwall

Thu Aug 03, 2017 3:38 pm

I've sent a lot of time researching, and learning about how to convert an EV's ~24 kWh battery pack into a DIY powerwall. There are a lot of videos on YouTube, and even some that suggest it's VERY easy to do - but it isn't, and not exactly easy to tie into a solar array set up with microinverters. Also, you're dealing with high voltages that can cause serious harm, so it isn't exactly a learn-as-you-go DIY project.

Here's a pretty good video that lists what's involved in setting up battery storage that I think was done right.

https://www.youtube.com/watch?annotatio ... kXTqNqxK3s

After watching it, and pricing out the components, I'm quite convinced it isn't worth the time or expense, just like a Powerwall isn't worth it either - especially if you live in an area with cheap kWh's. While it's a fantastic concept, I can't see it every paying for itself as things break down, and batteries are, by design, consumables.
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redpoint5
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Re: Bolt as a Powerwall

Thu Aug 03, 2017 5:05 pm

Since the battery is such a large expense on an EV, it makes sense to have it serve multiple uses. Some households have a generator to provide emergency power when the grid is down. It would be neat to have an EV battery take the place of the generator.

If EVs were designed with 2-way power in mind (drawing from, and feeding to the grid), I doubt the added expense would be very much. I wonder if the same charging circuit, with a little modification, could invert the DC energy and feed it back to the grid?

It would be very cool if EV owners were given an incentive to opt in to supplying the grid during peak periods to help load balance. Perhaps an app that notifies the owner of an upcoming peak, and gives them the option to sell their electricity at the higher price.

On a tangent thought, a pilot study was done between the utility and some i3 owners that notified them of peak demand and gave them the option to delay charging their vehicles.

https://www.pge.com/en/about/newsroom/newsdetails/index.page?title=20161114_pge_and_bmw_partner_on_next_phase_of_pilot_studying_advanced_electric_vehicle_charging_

PV1
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Re: Bolt as a Powerwall

Thu Aug 03, 2017 5:17 pm

Cars with DCQC already have the capability. Those two big pins run through a contactor straight to the battery. The only thing they might need is a firmware update so the car can recognize V2G/V2H connections.

An off-board inverter/charger could handle both charging the car and running the house from the battery. DIYing something actually might not even be that difficult if you can find a system that can handle a 350-400 volt battery bank. However, you definitely need to know what you're doing and how to handle high voltage before attempting anything like that.
2012 i-MiEV ES with quick charge - White
2012 i-MiEV ES with quick charge - Silver
2017 Bolt EV LT - Orange Burst

11.8 kW Solar Array

dandrewk
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Re: Bolt as a Powerwall

Thu Aug 03, 2017 7:51 pm

Nissan developed and actively promoted a system a VTG system for the Leaf. I'm not sure if it ever was offered in the USA though.

When I was in Tokyo a few years ago, Nissan had a big showroom right in Ginza. They were very big on promoting the VTG system. But then, this was about a year after that awful earthquake/tsunami knocked out power for millions of Japanese.

Once longer range EVs become prevalent, it's only a matter of time before somebody develops a turnkey system for a Bolt (etc) power wall. I'm all for opting in.

redpoint5
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Re: Bolt as a Powerwall

Thu Aug 03, 2017 7:56 pm

PV1 wrote:Cars with DCQC already have the capability. Those two big pins run through a contactor straight to the battery. The only thing they might need is a firmware update so the car can recognize V2G/V2H connections.

An off-board inverter/charger could handle both charging the car and running the house from the battery. DIYing something actually might not even be that difficult if you can find a system that can handle a 350-400 volt battery bank. However, you definitely need to know what you're doing and how to handle high voltage before attempting anything like that.


Yes, that does sound relatively simple. There is the added cost of needing another inverter.

I'm just wondering if the existing charge controller on the car could be designed to also serve as an inverter with relatively little added cost? I'd never need more than 6.6 kW (or whatever the L2 limit is) at home.

SeanNelson
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Re: Bolt as a Powerwall

Fri Aug 04, 2017 5:54 am

redpoint5 wrote:If EVs were designed with 2-way power in mind (drawing from, and feeding to the grid), I doubt the added expense would be very much. I wonder if the same charging circuit, with a little modification, could invert the DC energy and feed it back to the grid?

This is a little trickier than you might first imagine because the Grid runs on AC power and anything that feeds into it has to be synchronized with the 60Hz (50Hz in some regions) line frequency. Power companies usually need to certify the equipment to do this to make sure it doesn't cause problems for the grid.

Feeding power into the grid is pretty common (think of all the solar installations), so the equipment is readily available. But you should never, for example, run an A/C inverter from the 12V battery terminals of your car and plug its output into one of your wall sockets hoping to feed power into your house circuitry. It will end badly.

MichaelLAX

Re: Bolt as a Powerwall

Fri Aug 04, 2017 7:03 am

During the three years that I leased my Chevy Volt, I purchased and installed the EVExtend system which would provide 1,000 watts of 120v AC (later upgraded to 1,500 watts) to my apartment in an emergency from my Chevy Volt.

I removed it when the lease ended and I returned the Volt:

http://www.evextend.com/Emergency-Power-Kit.php

alevek
Posts: 44
Joined: Sun Nov 20, 2016 11:41 am

Re: Bolt as a Powerwall

Fri Aug 04, 2017 11:30 am

First EV car maker to offer that as an option will hit it out of the park. I'm amazed that Tesla hasn't offered it yet.

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