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I attached a 150A fuse holder to the little metal shield just in front of the battery. It's conveniently removable (with a single nut) for drilling the mounting holes. I used half of a two foot 2AWG red battery cable (with strenuous conformal bending) to connect the top of the fuse holder to the + battery clamp. I used half of a six foot 2AWG black battery cable, and connected it to the grounding stud on the "firewall". Someone here pointed out (thank you!) that you shouldn't connect the DC-AC inverter to the negative battery terminal, because there is a current sensor from it to chassis ground, and you'll throw a code when you pull "excess" current with an inverter load. The bottom + output from the fuse holder and the - output from the firewall are then connected to a 175A Anderson connector (commonly used for forklift charging). The cables loop under the fuse holder and come up on the driver's side, and the Anderson connector (with its cover) sits in the small space on the driver's side of the fuse holder, ready to be plugged into the DC-AC inverter.

Works like a champ with my (expensive) 1500W true sine-wave inverter and ten foot 2AWG welding cable DC extension. All parts were purchased from Amazon.

Note that I did this after buying a pre-made wiring set for my Volt. It works great. That company does not yet have a solution for the Bolt, so I made my own.
 

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Requested photos. Can't see the ground attachment, nor the bottom of the fuse holder, but the described process should be clear. Probably could have used the much smaller 120A Anderson connector, but I'm a belt-and-suspenders kind of guy, and opted for the 175A model to be certain.

I like how the fuse holder conforms to the angle of the chassis, and provides adequate clearance. Lucky happenstance.

I also added some rubber to the red power cable where it comes closest to the big electrical connector bracket to the passenger side of the battery.

The battery positive terminal cover flap also needed some trimming.
 

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Parts list, from Amazon:

2AWG Battery cables - [ame]https://www.amazon.com/gp/product/B075SHTY3H/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1[/ame]

Fuse holder (with 150A fuse) - [ame]https://www.amazon.com/gp/product/B01CT4ZJHS/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1[/ame]

15' 2AWG Welding cable for DC extension - [ame]https://www.amazon.com/gp/product/B0167K786A/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1[/ame]

175A Anderson cover - [ame]https://www.amazon.com/gp/product/B077SQ862P/ref=oh_aui_detailpage_o02_s02?ie=UTF8&psc=1[/ame]

175A Anderson connector - [ame]https://www.amazon.com/gp/product/B017U4P9U4/ref=oh_aui_detailpage_o02_s03?ie=UTF8&psc=1[/ame]

If you're OK with the 120A Anderson connectors, they come in pairs, with covers -

[ame]https://www.amazon.com/gp/product/B01MS4YJTE/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1[/ame]

Very expensive, but well-regarded 12V DC to 120V AC 1500W pure sine-wave inverter -

[ame]https://www.amazon.com/gp/product/B00AYH686E/ref=oh_aui_search_detailpage?ie=UTF8&psc=1[/ame]

As always, I assume no responsibility for damage, injury or death from fiddling with your Bolt.

Full disclosure, I threw a trouble code which illuminated the "check engine" light when I attached to the positive battery terminal. (It sizzled a bit, even with the car "off".) The check engine light went off after a couple of drives, but no doubt the techs will find the trouble code when I have the recalls done.
 

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Or you could just get yourself a small generator. It would probably cost less than $200 and save messing with your Bolt.
 

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Or you could just get yourself a small generator. It would probably cost less than $200 and save messing with your Bolt.

If you have a generator you also have to have gasoline for it, if you want to be able to run your generator for as long as the Bolt would provide power you'd need a decent amount of gasoline and a place to safely store it.


You could conceivably run a 1500W inverter at full load from a full Bolt battery for 38 hours. Of course you really can't because you lose some energy with the DC/DC conversion and while pure sine wave inverters are generally very efficient you'd lose some there to so let's say you could provide 1500W for 30 hours.

To run a Honda EU2200i (similar output as a 1500W inverter) for 30 hours at it's rated load you'd need almost 10 gallons of gasoline. Most people, if they have anything, has a 2.5G gas can (that's what I have).

Also, if you have gasoline stored you need to either rotate it by using it in an ICE and replenishing it or use some kind of fuel stabilizer (even then you should rotate it every year or so).

Granted, even mild "prepper" types are going to have that kind of gasoline on-hand anyways.
 

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I started on this odyssey by considering a $7000 10kWh Tesla PowerWall for power backup in an emergency. I live in earthquake country, and it's a matter of when, not if, the grid is taken down by one for an extended period.

Then I realized that I already have the equivalent of six of them sitting in the driveway in the Bolt. I also have another PowerWall worth of battery storage in the Volt, along with the equivalent of nine more in its gas tank. Ten gallons more of gas in the garage gives me ten more PowerWalls of storage. That's a total of 26 PowerWalls of energy storage capacity. To put dollars to it, that's $182,000 worth of PowerWall storage equivalent in my two cars plus 10 gallons of gas, if I can only tap into this 260kWh of energy.

Enter the inverter setup, which came in at about eight hundred bucks. Sounds like a lot, but look at what I got. Yes, I know that it can be done more cheaply, but like I said...I'm a belt and suspenders type of guy. In an emergency, I want bullet-proof. If I can keep usage around 3kWh per day, this should get me *at a minimum* a month of emergency backup power.

BTW, the Volt is a real handy, quiet and clean, transportable electric generator, with the relatively simple addition of a 1500W sine-wave inverter. Installed in less than an hour. The Bolt took longer...

BTW, the Honda generator mentioned above is a thousand bucks.
 

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A reminder...you can't get 60 kWh out of these systems. There are inefficiencies in the DC-DC and the inverter, and standby losses from the Bolt's 12V systems....you might get 60-70% out at high loads, at low loads you will drop to closer to 50% system efficiency.

Think 300W for 100 hours, or 600 W for 60 hours, etc. Conservatively.

And I think the highest continuous load is ~1150-1200W AC, above that you will start to draw the AGM down.
 

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A reminder...you can't get 60 kWh out of these systems. There are inefficiencies in the DC-DC and the inverter, and standby losses from the Bolt's 12V systems....you might get 60-70% out at high loads, at low loads you will drop to closer to 50% system efficiency.

Think 300W for 100 hours, or 600 W for 60 hours, etc. Conservatively.

And I think the highest continuous load is ~1150-1200W AC, above that you will start to draw the AGM down.
Yup. It's why I derated the 260kWh total in my "system" to about 100kWh. (3kWh a day for 31 days.)

I've also read elsewhere here that GM engineers have indicated that the DC-DC in the Bolt is capable of 1600W. The Volt's is, too. That's why the company that makes the Volt inverter wiring harness states that a 1500W inverter is the maximum usable, and provides 120A Anderson connectors. 120A at 12V is 1440W. Barely adequate, in my estimation, although I wouldn't anticipate pulling 120A, except for surge motor startups.
 

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If I only want to run a refrigerator (150W), charge my phones/laptops, and run 1000W microwave ocassionally, then the Bolt battery should last me more than a week easily.
 

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Yup. It's why I derated the 260kWh total in my "system" to about 100kWh. (3kWh a day for 31 days.)

I've also read elsewhere here that GM engineers have indicated that the DC-DC in the Bolt is capable of 1600W. The Volt's is, too. That's why the company that makes the Volt inverter wiring harness states that a 1500W inverter is the maximum usable, and provides 120A Anderson connectors. 120A at 12V is 1440W. Barely adequate, in my estimation, although I wouldn't anticipate pulling 120A, except for surge motor startups.
Keep in mind that these sine wave inverters are about 82-85% efficient.

So at 1440 W output, they would need 120A/0.82 = 146 A input at 12V. !

Equivalently, 1600 W at 12V = 133A, and after the inverter it is 1600W*0.82 = 1300W.

I know I ran a 1200W space heater on mine, and voltage on the 12V battery was slowly drooping over the course of an hour. I figured that the DC-DC was 1500W out, and I was pulling the AGM down.
 

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Keep in mind that these sine wave inverters are about 82-85% efficient.

So at 1440 W output, they would need 120A/0.82 = 146 A input at 12V. !

Equivalently, 1600 W at 12V = 133A, and after the inverter it is 1600W*0.82 = 1300W.

I know I ran a 1200W space heater on mine, and voltage on the 12V battery was slowly drooping over the course of an hour. I figured that the DC-DC was 1500W out, and I was pulling the AGM down.
Absolutely correct. I wouldn't dream of attempting to pull even half of the 1500W inverter output on a continuing basis. I'd plug my Kill-a Watt meter into the inverter, then loads into the meter, to be certain I wasn't doing anything beyond what I'm comfortable with. With power devices, I typically spec twice the capability of what I'm expecting to actually use. In my experience, you can usually count on US manufactured goods to have significant design margin built into their products. I've found that the cheap Chinese stuff typically has no performance margin whatsoever, and in fact often don't even meet the basic design specs. Let the buyer beware.
 

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Further information on my setup.

I tied the negative cable of my inverter under-hood connector to the same location that the vehicle battery negative terminal is attached to. The vehicle battery negative cable goes through a toroidal current sensor, then to the grounding stud. The inverter under-hood connector negative cable does not go through the current sensor. The grounding stud is on the drivers side wheel well, and as such is a PITA to get to, but I struggled and was successful. I highly recommend being very careful about dropping anything (like tools) when you're elbow deep under the hood. I didn't drop anything, but I'm uncertain if it would be retrievable if I did. There are also several sharp metal surfaces in there. I have multiple superficial cuts on my hands to prove it.

I modified the procedure a bit. I've chosen to shift the Bolt into "L" before exiting from the passenger side, instead of "N". I'm doing this because the Bolt will hold its position when in "L", and it won't while in "N". I don't know if there's any power use difference between the two. (If any of you know, please speak up.) Of course, the Bolt has the parking brake set in either case.

I hooked up a 1500W pure sine-wave inverter, and plugged in a (heat shrink type) heat gun as a load. The heat gun has two settings: 900W and 1200W. Note that these are both on the load side of the inverter, so the vehicle draw is probably closer to approximately 1100W and 1500W, considering conversion efficiencies. Unfortunately, I don't own a DC clamp-on current meter.

Load current was provided by a Watt's Up meter.
At 1200W AC load, the vehicle DC-DC couldn't keep up, and the aux battery voltage dropped slowly.
At 900W AC load, the battery voltage cycled between 13.66V and 13.88V, measured with a reliable multimeter. I suspect that these values represent the hysteresis of the DC-DC to AGM battery system..."on" when the battery drops below 13.66, and "off" when it gets to 13.88. The cycling rate was probably every 5-10 seconds. That's a lot of cycles, but the cycle rate with a realistic load should be *much* slower.

I'm going to let it run with the 900W AC load for a couple of hours to verify that the system functions as expected. Using a gun-type IR temperature meter, I checked connection temperatures at the studs where the inverter cable is connected to the battery and grounding stud, as well as everywhere else, and am seeing no temperature rise beyond ambient. Surprising, when you consider I'm drawing around 100A through them all.

FYI. When I tried tying the ground lead elsewhere than the designated stud, I first-degree burned my fingers testing for temperature rise. Stupid!
 

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I modified the procedure a bit. I've chosen to shift the Bolt into "L" before exiting from the passenger side, instead of "N". I'm doing this because the Bolt will hold its position when in "L", and it won't while in "N". I don't know if there's any power use difference between the two. (If any of you know, please speak up.) Of course, the Bolt has the parking brake set in either case.
Have you tried putting the car into Neutral but fasten the drivers seat belt to prevent the car from shutting off?
 

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Have you tried putting the car into Neutral but fasten the drivers seat belt to prevent the car from shutting off?
Nope. I hadn't seen that fastening the seat belt was necessary in either case, or in any of the previously posted "procedures". I ran my setup (in "L") for three hours, and the Bolt didn't shut down. I chose "L" because my driveway has a slope, and I don't have any effective wheel chocks to back up the parking brake. I just ordered some to be added to my emergency kit.

After three hours, the only location with any temperature rise was in the fuse holder. It was at 102F, where everything else under the (cracked open) hood was at ~80F. Outside temps at the time were about 70F, and the Bolt was in direct sunlight the whole time.

The Bolt reported that 12 miles were used in three hours for a what I feel is a maximum vehicle-sustainable load of 900W AC, which probably translates to about 1100W-1200W at the 12V aux battery. The Bolt reported 251 miles of range at the start. If you extrapolate that to 240 total miles of range, the Bolt can probably comfortably sustain that load for about two days. (240mi/12mi) x 3hrs is 60hrs, so I figure 48hrs should be reasonable. In an emergency, I wouldn't have anywhere near that sustained draw, so expecting a week of backup with this setup is reasonable, in my estimation.

I may run a more realistic experiment with my garage freezer plus a low, fixed draw of 50W or so for a couple of days to get better data. Plus, what I've got now isn't pretty under the hood (I beat up the cables and connectors pretty good messing with routing and such), so I want to replace a cable and an Anderson connector (with a smaller 120A version) to make it look like it all belongs there. This may require that I uninstall the whole mess to enable torch soldering, and I'll try to get a couple photos of the final setup on the bench top.

If it weren't for the difficult access of the ground stud on the wheel-well, this would be a very simple project for a careful do-it-yourselfer.
 
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