DIY V2L: My Mach-E got my home through power outage with flying colors

[iam-s-Hon]

yes, my electrical panel is in the garage... but location of panel is not important. what is important is that you MUST isolate from the Grid before connecting any kind of 'generator'. So, you MUST be able to get to your 'primary disconnect'.

Second, is where to 'backfeed'. If you have a NEMA 14-50 240v outlet, it's simple since you can use one custom cable to feed both 'legs'. If your home charger is hardwired, you need to find one 'regular' outlet that is on each of your 'legs', and have two 'suicide adapters' to backfeed from the inverter to both L1-L2 of your house.

This type of 'manual' transfer off/on the Grid with a 'portable Generator' carries some risk of exposure to live prongs if you don't follow correct order of turning things off/on. But, keeps the cost down for occasional emergency use versus fully automatic or integrated transfer switch systems like the Tesla Powerwall or a permanent installation of a hybrid Solar inverter with battery backup

Got it.

Well, I can shut off at the panel w/ the main switch, disconnect the solar array from the outside for safe measure, too. Easy to shut off all my 240v circuits (baseboard heaters). I have a nema 15-40 plug (to use mobile charger as backup to failure w/ the homeflex evse). With some parts, and a GF willing to standby in case of emergency, this may possible. I don't have enough outages to justify a wall battery backup at current price point. But when they occur they last long enough that this DIY would suffice.

This may be an interesting weekend project. Unless I get a Lightning first and just run an extension cord or 2.

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[dtbaker61]

Got it.

Well, I can shut off at the panel w/ the main switch, disconnect the solar array from the outside for safe measure, too. Easy to shut off all my 240v circuits (baseboard heaters). I have a nema 15-40 plug (to use mobile charger as backup to failure w/ the homeflex evse). With some parts, and a GF willing to standby in case of emergency, this may possible. I don't have enough outages to justify a wall battery backup at current price point. But when they occur they last long enough that this DIY would suffice.

This may be an interesting weekend project. Unless I get a Lightning first and just run an extension cord or 2.

the hard part is fabricating the 2awg cable.... you need a BIG crimper and some practice to make good crimps with lugs that size, and the Anderson lugs are SUPER stout and hard to crimp. The materials are about $75; I've made a couple sets for people that don't have big tools for $225 incl shipping in the 'lower-48'.

other than that, all you need is the Inverter, and output cable... which can be a 30a 'range whip', or fabricated with 10ga extension cord and DIY 14-50 plug end.

hhhmmmm, maybe I should whip together a little Shopify site and pre-fab some cables ?!

 

[Blue highway]

Really cool idea.

Does anybody know what the current capacity of the HVB to LVB converter is in the MME?

 

[dtbaker61]

Really cool idea.

Does anybody know what the current capacity of the HVB to LVB converter is in the MME?

150amps in lower trims, GTs are a little higher.

 

[AKgrampy]

Very nice! I run a transfer switch with a whole house 10kW generator. Big enough to run our well and operate everything in the house. We have had up to 7 day outages in the winter (3 days was my longest) so need a bit more than what the Mach can provide.

 

[Fremont Kid]

While creative, innovative and meets needs for a short time frame, I have needed a whole-house backup system with automatic transfer switch. Still the most cost-effective backup system.

For those desiring to replicate this system I want to offer this caution: Be able to understand such a system from the 'inside-out'. If you send any electricity out to the grid during an outage you can electrocute workers trying to restore power for everyone. The OP did describe how he isolated his house from the grid.

 

[Howard]

Great write up and idea. If you setup the Shopify, don't stop with cables, setup the entire system as an option, cables, connectors, inverter. I bet there are a lot of folks that would be interested. I have a 2000 watt inverter that I connect to 12V posts. I only run one extension cord (10awg) to power up a couple of small loads (including the wife's coffee pot lol) at a time. I pull maybe 75-100 watts at most. You have definitely got me thinking about doing this. I would definitely be interested in a turnkey setup.

 

[Madtroniks]

I’ve heard of many EV owners who were charging at Tesla stations during bad weather and power outages in Houston.

They were using that to power essential items at home.

This is an excellent benefit of having an EV and hopefully one day we can get reasonable prices on bi-directional charging stations.

 

[lindseybp]

cool stuff guys. My big takeaway….we have some darn smart people on this forum!

 

[nlions]

Last night we had a massive lightning storm in Santa Fe... knocked out power in my corner of town from 5pm yesterday afternoon to 5am this morning. I was kinda thrilled to get a chance to put my ePony thru the paces and power my 'whole house' as an emergency generator for a solid 12 hours.

I have:

- custom 2awg cables I fabricated connected to 12v+ and - connection points... capable of sustained export of 1500-2000 watts (150amps).

- 3000 watt pure sine 12vDC->120vAC inverter

- custom output (10awg) cable, 30a powercon at one end, NEMA 14-50 plug with L1-L2 jumpered to other. Enables up to 3000watts to either/both legs, but will not support any 240v loads (on purpose since I don't have any critical 240v loads).

After turning off all 240v branch circuits, and my 200a main to isolate from the grid, I plug MME 12v to inverter, and inverter output to NEMA 14-50 outlet... turn on the inverter, and turn 120v branch circuits back on.

The MME has to be 'on'
auto-timeout has to be 'off'
headlights and heat&A/C should also be 'off'

ran the house like a champ:

A few important safety reminders:
1. Don't forget to disconnect your home from Grid before doing anything else. You MUST turn off your 'main' breaker first! You do not want your backup generator to energize the Grid, and you do not want the Grid to come back on and argue with your generator.

2. you *should* turn ALL branch circuits off before starting Generator so all the loads don't hit at once.

3. if you turn on the generator before plugging in your 'backfeed adaptors' there will be exposed plug prongs that are energized, and present a significant shock hazard. You MUST make all connections from Generator to outlet(s) before turning the Generator on, and then

4. turn on only the branch circuits that you want to power... in my case, only the critical 120v loads like a few lights, refrigerator, and the internet/modem.


and some other interesting information regarding loads
background load including refrigerator, lights, internet modem bounced around 200-350 watts

and running the coffepot bumped the peak load up for a few minutes....

gotta say, I'm pretty happy to confirm that the MME can easily run my house for DAYS if needed.


...and these are the cables I fabricated and installed on the 12v to get a good solid connection capable of carrying 150amps. It is important to use big fat wire rated to carry up to 150a , with good terminals bolted securely to the connection points. The 'extra' alligator clamps are only for giving/getting a temporary 'jump' because they do not provide enough contact area to pass much current without heating up.

Looks intriguing. I have a solar system with battery and am protected that way but I'm not quite sure how you are charging the MME if you are going to power your house for days?

 

[dtbaker61]

Looks intriguing. I have a solar system with battery and am protected that way but I'm not quite sure how you are charging the MME if you are going to power your house for days?

Critical loads in my house consume about 5 kWhr/day....

This energy export unit *could* run the house for days without needing to charge the MME. Presumably, this would get most people through most 'typical' outages.

The point of documenting this solution is mostly to present an inexpensive option for people to consider 'Step 1' battery backup utilizing a <$500 inverter and the giant battery available in an EV rather than buying a separate stationary battery/inverter like a Tesla powerWall for $25k.

I happen to have solar on my house as well, but it is a battery-less grid tied system, so when the Grid goes down, the PV is down. When the grid-tied Inverter expires, I'll probably replace with a hybrid inverter, and add a small battery bank.... but for now, the MME is my mobile battery bank, and I don't have to buy stationary batteries that just sit there doing nothing most of the time.

 

[nlions]

Critical loads in my house consume about 5 kWhr/day....

This energy export unit *could* run the house for days without needing to charge the MME. Presumably, this would get most people through most 'typical' outages.

The point of documenting this solution is mostly to present an inexpensive option for people to consider 'Step 1' battery backup utilizing a <$500 inverter and the giant battery available in an EV rather than buying a separate stationary battery/inverter like a Tesla powerWall for $25k.

I happen to have solar on my house as well, but it is a battery-less grid tied system, so when the Grid goes down, the PV is down. When the grid-tied Inverter expires, I'll probably replace with a hybrid inverter, and add a small battery bank.... but for now, the MME is my mobile battery bank, and I don't have to buy stationary batteries that just sit there doing nothing most of the time.

Hopefully Ford will give the MME the F150 Lightning capability

 

[dtbaker61]

I’ve heard of many EV owners who were charging at Tesla stations during bad weather and power outages in Houston.

They were using that to power essential items at home.

This is an excellent benefit of having an EV and hopefully one day we can get reasonable prices on bi-directional charging stations.

yes, using DCFC stations to charge, and then consuming the energy at home is one way to go.... but problematic if the Grid is down for miles, or roads are impassible on the way to the DCFC station; and the cost is not attractive since the price at many stations is 4x the retail rate for electricity at home.

A better solution for long term is a small (or large) Solar system at your home, or wherever your EV is parked during the day most of the time.... and take advantage of daytime solar, even at L1 charge speed, to 're-fuel' your EV and recover your commute use to go home with a near-full battery.

bi-directional chargers via DC port would be really nice, or Solar charge controllers for direct DC charging. It's easy to have a 400+vDC solar string, all we need is a MPPT charge controller programmed with the EV 'end of charge' and 'float' voltage and the protocol to enable charging (and/or bi-directional export of the HV direct to a hybrid inverter as 'pv input'.)

 

[dtbaker61]

Hopefully Ford will give the MME the F150 Lightning capability

How much more would you want from the MME ?

We can get 1500watts out via the 12v connection points.
We *could* get 5000 watts out by tapping the HV heater wires.
or, we *could* get 50kW out if Ford enabled bi-directional J1772 port
or, we *could* get 100kW out with bi-directional DC port access.

 

[dtbaker61]

While creative, innovative and meets needs for a short time frame, I have needed a whole-house backup system with automatic transfer switch. Still the most cost-effective backup system.

yes, but the more you run, and the more automated it is... the more expensive. Something with auto-transfer, critical loads sub-panel, and a 10kWhr battery would start at $20-25k.

For those desiring to replicate this system I want to offer this caution: Be able to understand such a system from the 'inside-out'. If you send any electricity out to the grid during an outage you can electrocute workers trying to restore power for everyone. The OP did describe how he isolated his house from the grid.

absolute requirement to understand this when using ANY 'backup generator'.

easy step up in safety is to have a manual or automatic transfer switch the makes it impossible to backfeed while grid is connected. BUT, this approach for 'manual transfer' is safe as long as you follow procedures and do everything in the right order.

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