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Charging Powerwalls from generator

davidwpb

Member
May 17, 2019
48
10
west palm beach, florida
I know this doesn't seem to make sense, but I was wondering if anyone has any experience or has read about anyone trying to charge their Powerwalls from a generator. I'm about to have 3 Powerwalls installed and I have a 2018 Chevy Volt. On cloudy days during a potential hurricane outage in Florida, I could use an inverter to charge my Powerwalls. Questions I have regarding this proposed setup.
1. Can you charge from 120v or would you need to do 240v to do it properly. If so I need to get a more expensive inverter.
2. Inverters fluctuate output based on demand, the 240v option I found is larger than than the car should probably have hooked up, will it try to push out the max or will it not sense a draw load?
3. Where should inverter tie into setup, I'm assuming the same place the solar inverter feeds the powerwalls.
 

Ampster

Active Member
Oct 5, 2012
1,780
477
Kenwood, California
You will need a transfer switch to tie a generator into your system. It all depends on the location of your equipment. The Powerwalls may also not be able to use the output from a generator. Some generators do not put out clean power. The simplest solution would just be to try to charge your Chevy volt directly from the generator to see if it will work.
 

gpez

Member
Apr 25, 2019
689
567
USA
The "Powerwall 2.0 Backup Runtime Extender" thread linked above is excellent.

I too have a 2018 Chevy Volt and opted to simply get a high quality inverter for extreme emergencies to run critical items off of while the Powerwall charges off of the solar. Personally I found the option to tie my Volt to my home during an outage is simply too costly and complicated with the current residential product offerings.
 
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davidwpb

Member
May 17, 2019
48
10
west palm beach, florida
You will need a transfer switch to tie a generator into your system. It all depends on the location of your equipment. The Powerwalls may also not be able to use the output from a generator. Some generators do not put out clean power. The simplest solution would just be to try to charge your Chevy volt directly from the generator to see if it will work.
Thanks. I'm trying to use my Chevy Volt as the Generator to charge my Powerwalls. The generator comment was because this was the closest thing that others on the forum might have done and I could use that as a comparison point.
 

davidwpb

Member
May 17, 2019
48
10
west palm beach, florida
The "Powerwall 2.0 Backup Runtime Extender" thread linked above is excellent.

I too have a 2018 Chevy Volt and opted to simply get a high quality inverter for extreme emergencies to run critical items off of while the Powerwall charges off of the solar. Personally I found the option to tie my Volt to my home during an outage is simply too costly and complicated with the current residential product offerings.
Great idea, just shift some load off the powerwall that will run consistently and get a similar result. In my case probably run garage fridges/freezers. What inverter did you go with? I was trying to get the setup from EVextend.com but they stopped selling right as I was researching this option.
 

gpez

Member
Apr 25, 2019
689
567
USA
Great idea, just shift some load off the powerwall that will run consistently and get a similar result. In my case probably run garage fridges/freezers. What inverter did you go with? I was trying to get the setup from EVextend.com but they stopped selling right as I was researching this option.

Exactly! Plus the set up is a bit more flexible as the inverter can be used anywhere the Volt is - camping, tailgating, and maybe down the street at a neighbors house during an emergency.

https://www.amazon.com/gp/product/B07G36Z2TH - Giandel 1200w pure sine inverter. Went with this as it was a highly rated, pure sine wave (wanted to avoid modified sine wave as things with motors and computer chips generally don't like modified sine) and has enough power for my loads without overtaxing the gen 2 Volt's traction battery to 12v system.

https://www.amazon.com/gp/product/B07G79K5SF - Rough Country 7 FT Quick Disconnect. Just got this and I think it's almost the exact same thing evextend is selling. There are guides (link below) on how to remove the trunk cover, screw this on to the traction step down transformer, and run it to the charging cable storage on the left side of the trunk. Have not tried this yet.

https://www.amazon.com/gp/product/B079SQMNQ3 - Spartan Power 2 AWG 5 Foot Alligator Clamps. My original plan and now backup plan for hooking the inverter up. I tested this and the clamps are juuuust barely thin enough to clamp on to the battery (if you've popped your Volt trunk open you'll know how tight space is around the 12v battery). It'll work in a pinch but I think the quick disconnect option is going to make more sense. I'll likely keep these as I have a Ford Explorer family hauler (2 kids) that we could potentially hook up to the inverter for tailgates later.

Credit where due: 2016+ Inverter install guide with photos [Archive] - GM-Volt: Chevy Volt Forum has a lot of this info which is where I was working from.
 
Last edited:

miimura

Well-Known Member
Aug 21, 2013
6,362
6,065
Los Altos, CA
You guys need to keep in mind that there are fundamentally two different kinds of battery inverters.
1. Mobile inverters that you would use when camping, etc. These are like a portable ICE generator in that they generate their own free-running AC waveform. They cannot be connected to a grid or micro-grid.
2. Grid Tied inverters that synchronize to a grid or micro-grid. They will not output anything until they see an AC waveform. They can be used to inject power into a grid or micro-grid. Some are designed for solar with MPPT and some can also do fixed or variable power taken from a battery or other power source.

DO NOT try to connect that Giandel inverter to your home hoping to add energy to your Powerwalls. If you want to connect your refrigerator and central heat furnace to your Volt to reduce the draw on your Powerwalls, that's fine. Just don't connect that mobile power inverter and your home's power system together.
 
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gpez

Member
Apr 25, 2019
689
567
USA
You guys need to keep in mind that there are fundamentally two different kinds of battery inverters.
1. Mobile inverters that you would use when camping, etc. These are like a portable ICE generator in that they generate their own free-running AC waveform. They cannot be connected to a grid or micro-grid.
2. Grid Tied inverters that synchronize to a grid or micro-grid. They will not output anything until they see an AC waveform. They can be used to inject power into a grid or micro-grid. Some are designed for solar with MPPT and some can also do fixed or variable power taken from a battery or other power source.

DO NOT try to connect that Giandel inverter to your home hoping to add energy to your Powerwalls. If you want to connect your refrigerator and central heat furnace to your Volt to reduce the draw on your Powerwalls, that's fine. Just don't connect that mobile power inverter and your home's power system together.

Come on man, just read my post. I literally said that I'm not going to tie my Volt to the house because the tech isn't there and so I went with the standard (non grid tie) route.
 
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miimura

Well-Known Member
Aug 21, 2013
6,362
6,065
Los Altos, CA
Come on man, just read my post. I literally said that I'm not going to tie my Volt to the house because the tech isn't there and so I went with the standard (non grid tie) route.
You were replying to a guy that wanted to "shift some load off the Powerwall". It was not completely clear that he intended to move the loads off the Powerwalls or interconnect an inverter to the Powerwalls since the subject of the thread is "charging powerwalls from a generator". He also said up-thread that he did want to charge the Powerwalls from his Volt.

I was just trying to make sure that people understood the difference. However, you are right that I should not have singled you out with the inverter you chose and assume that you would try to interconnect them. Sorry about that.
 

gpez

Member
Apr 25, 2019
689
567
USA
You were replying to a guy that wanted to "shift some load off the Powerwall". It was not completely clear that he intended to move the loads off the Powerwalls or interconnect an inverter to the Powerwalls since the subject of the thread is "charging powerwalls from a generator". He also said up-thread that he did want to charge the Powerwalls from his Volt.

I was just trying to make sure that people understood the difference. However, you are right that I should not have singled you out with the inverter you chose and assume that you would try to interconnect them. Sorry about that.

I appreciate that. davidwpb in reply #6 said he liked the idea of load shifting and powering his fridge/freezer vs grid tie, I believe he understands as well.
 

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