High voltage hybrid inverter (GW6000-EH) with EV battery (Chevy Volt)

[yasko]

Hi everyone,

In this thread I will try to share my experience with these new HV hybrid inverters and EV batteries working together as energy storage system.
I've been planing to build a small PV system for a long time. A hybrid system with big battery
I was looking for an used EV batteries for some time and had a chance to get a battery form a Chevy Volt, year 2013. My first plan was to use a 48V hybrid inverter, but the reconfiguration of a Chevy battery is not an easy task. So I've decided to go with a HV hybrid inverter. These machines can work with batteries in the range 100-450VDC, but there is a limited selection of batteries. And communication protocols between the inverter and the battery are closed and proprietary. But I took the challenge and after two months of mounting, wiring, coding and hacking I have a working system.

It’s based on Goodwe GW6000-EH with two modules from a Chevy battery (30S+24S with nominal voltage of 202V). Cells monitoring is done via an original BMS (BICM modules). They are connected via CAN bus to a SBC (Raspberry Pi). There is a second CAN bus connected to dedicated port of the inverter. A small program that runs on Raspberry translates the information form battery BMS in format which can be understood by inverter. That way the inverter is happy and knows the most important parameters of the battery. (SOC, charge voltage and current and etc.). The SBC is an overkill, but it makes debugging easier. I’m planning to replace it with dedicated controller on later stage (may be SimpBMS).
The inverter has many configuration options and I’m impressed by the build quality, but more on that later.
The project is still a WIP and there are many things to improve. But I can say for sure that the system works as expected.
I want to thank the community for the valuable information that found on the net regarding various aspects of the project.

P.S
Attached picture of inverter

 

[daromer]

Nice!

Some images would be appreciated. Both on the physical install but also on software side if you have

 

[Cheap 4-life]

Sounds cool. A high voltage setup. Be careful with the high voltage.
I also use Chevy volt batteries. I use the newer gen2.
Reconfiguring the Chevy volt full packs to 48v (or 60v like I use) is easy. The gen2 full packs have three 60v and four 48v batteries. Unscrew-loosen the allthread. When there’s enough space then slide zipties in to temporarily hold the cells of the individual batteries together into 48v and 60v packs. Then fully remove the allthread. Then cut the allthread and reinstall all thread to the now separated packs. Then sell the individual 60v packs and keep the four 48v packs. Rinse and repeat if you want more than four 48v packs. There isn’t any cutting of busbars necessary. It’s as easy as I explained above.
My inverters (grid tie and offgrid) can all use a 60v nominal battery so I decided to use the 60v sections of the full pack.

 

[yasko]

@Cheap 4-life - thanks for the instructions. I see that can be done easily but already gone in HV direction. I'm still not sure whether the HV setup is suitable for DIY projects and there are different pros and cons.
Here picture of the current battery setup with an opened cover. I'm going to move batteries to metal storage cabinet in the next few days.

 

[prepared1]

Hi everyone,

In this thread I will try to share my experience with these new HV hybrid inverters and EV batteries working together as energy storage system.
I've been planing to build a small PV system for a long time. A hybrid system with big battery
I was looking for an used EV batteries for some time and had a chance to get a battery form a Chevy Volt, year 2013. My first plan was to use a 48V hybrid inverter, but the reconfiguration of a Chevy battery is not an easy task. So I've decided to go with a HV hybrid inverter. These machines can work with batteries in the range 100-450VDC, but there is a limited selection of batteries. And communication protocols between the inverter and the battery are closed and proprietary. But I took the challenge and after two months of mounting, wiring, coding and hacking I have a working system.

It’s based on Goodwe GW6000-EH with two modules from a Chevy battery (30S+24S with nominal voltage of 202V). Cells monitoring is done via an original BMS (BICM modules). They are connected via CAN bus to a SBC (Raspberry Pi). There is a second CAN bus connected to dedicated port of the inverter. A small program that runs on Raspberry translates the information form battery BMS in format which can be understood by inverter. That way the inverter is happy and knows the most important parameters of the battery. (SOC, charge voltage and current and etc.). The SBC is an overkill, but it makes debugging easier. I’m planning to replace it with dedicated controller on later stage (may be SimpBMS).
The inverter has many configuration options and I’m impressed by the build quality, but more on that later.
The project is still a WIP and there are many things to improve. But I can say for sure that the system works as expected.
I want to thank the community for the valuable information that found on the net regarding various aspects of the project.

P.S
Attached picture of inverter

Yasko: I applaud what you are doing. I just joined this forum, but have been looking into this subject for several years. I like the idea of being able to take advantage of large, pre-assembled battery units that don't work for the majority of the buyers, and are being sold for less per kWh. I'm not personally interested in building up packs out of 18650 cells. I'd also like to utilize components built for the harsh demands of auto use. In some cases, even the enclosure can be used. (ie the BMW cases)

But I'm lost when it comes to the computer portion. Been hoping to find someone to lean on for help in that area.

Keep developing your system. It sounds very interesting.

 

[yasko]

@prepared1 thank you for the kind words! I'm totally agree with your comments. Using pre-assembled battery has many advantages and I'm impressed with build quality of these batteries. This particular battery (year 2012) is around 86 % SOH (38.5Ah/45Ah) and works very well. I've done some initial cell balance and now they stay in 10-12 mV range during charge/discharge cycles. Here is a cell histogram at 17A discharge (around 3500W load)


Regarding computer portion - I think can help here. I'm going to describe my computer system and share the code on GitHub, but need some more time for testing.

Now a few words about whole solar system:

• PV panels - 1700Wp, 4x435W, Longi Solar (planning to add a few more)
• Inverter Goodwe GW6000-EH, on-grid
• battery - Chevy Volt (gen 1). Now I'm using two modules (24S and 30S) for total 54S configuration with usable capacity around 7kWh
• Raspberry 3B+ with two channel CAN HAT (SeeedStudio) for BMS and inverter communication.
• some MCB's for protection and a lot of wires

Here is the inverter label with major parameters:



And just finished a new storage for batteries. Now I have room to add the last battery module and go to full 96 cell configuration.

 

[1.21 Gigawatts]

Really impressed!!
I have some questions,

1. How did you workout what the requests the Goodwe inverter was asking the BMS? Did you use some kinda packet capture software like 'wireshark'?
2. Did you first need a working Goodwe compatible battery/BMS to capture what the inverter was asking? Or were you able to just connect to the inverter BMS com port and monitor requests, and then look up what they mean?
3. Is 'Can Frame' the communication protocol?

Would love to see a video detailing your reverse engineering process and hardware/software setup.
Awesome work.

 

[yasko]

It's a long story about making Goodwe inverter work with DIY batteries. I liked the idea of making a video, but I'm still working on the system, and that takes up almost all my free time. Now let's go to the questions:

1. This inverter support various type of batteries, each of them using its protocol. I was able to work out one of these protocols (so-called "default" Goodwe battery) using reverse engineering, and packet capture software helps a lot. I used a can-utils package, main tools to display, record, generate and replay CAN traffic. My hacking platform is SBC (Raspberry Pi) with two CAN bus interfaces and an additional USB to RS-485 adapter.
2. Second solution. I've just connected to the BMS port, monitored requests, and had a chance to figure out what they mean. It took some time, will describe the whole process later. Having a compatible battery is a good option, but that was out of my budget.
3. Communication between inverter and BMS is CAN bus-based and works by exchanging parameters via CAN frames, each with a different ID and payload (max 8 bytes). So you have one ID for the charging voltage and current of the battery, another one for the battery temperature, etc. The tricky part is finding the right ID and data format in the payload field.

Update 28.01.2021
Here is an example of a real CAN bus frame captured with "candump" utility:

can1 456 [8] 0D 0F 64 00 FA 00 1D 0C

The first column is the name of the CAN bus interface second is frame ID (0x456), the third is the size of the payload field, and the remaining is the payload data itself (8 bytes total). But what these bytes mean?
Indeed here we have four signed 16-bit integers encoded in LSB format - 0x0F0D, 0x0064, 0x00FA, 0x0C1D.
Let convert them to decimal notation and divide them by 10: 385.3, 10.0, 25.0, 310.1.
These four numbers are four parameters sent from the battery to the inverter. The first one is max charging voltage (385.3V) second is max charging current (10.0A), the third is max discharging current (25.0A), and the last one is min discharge voltage (310.1V). I'm sending these numbers based on my current battery setup of 94 cells. I want the inverter to charge each cell to max 4.1, so we have 94x4.1 = 385.4V and discharge to 3.3V/cell with specified currents. With the help of some other CAN frames, I can send all parameters needed by the inverter (GW6000-EH) to work with the default battery.

 

[prepared1]

Yasko and 1.21 Gigawatt:

Both topics are very interesting reads. Yasko, I like how you are doing your system. Looks great. Gigawatt sounds like he has some knowledge of protocols too, but not sure how far that extends. What I do know, is that isn't my forte. I'm good at sales, marketing, building, analyzing trends, etc. I just posted a long comment on his inquiry about making batteries work with Solax... hope that isn't mis-interpreted.

My approach to these battery systems reflects the work I did for my career. The industries I worked in could not afford downtime, so reliability was paramount. When I see people building batteries with cylindrical cells, I see multiple points of failure. There are certainly advantages to that approach though, and I don't discount them. But I've watched many videos of guys building large packs, and flipping around some sub-packs at the last second because they were oriented wrong. Or, dropping a pliers onto the battery by accident. To me, it is just too much risk. I like the clean, simple automotive packs that come with a nice cover, and some beefy terminals. Highly reliable, fair price, etc. Love your Volt batteries....

Just picked up some more batteries from Battery Hookup, and am now pushing 40 kWh. Am building my rack systems. There is a very real issue to consider with that too, as far as home insurance, and liability goes.

I need to get a handle on the BMS issue. Right now, my whole system is basically manual, for back-up in the event of loss of power. I need to get the whole system "online". This summer my first PV panels go up, near my hot water panels. So the clock is ticking.

 

[Cheap 4-life]

Prepared1, did you get the gen1 Chevy volt batteries battery hookup just had for sale?

 

[yasko]

After two months of working with EV batteries, I can only confirm what Prepared1 said. Nothing compares to work with them, helped me to make a clean and powerful ESS. I've just finished new storage for batteries. Here are pictures of my weekend work.


Тhat is an office storage cupboard with slightly modified construction to carry the weight of batteries. I also added stone wool insulation for additional fire protection.


All things together


The "brain" of the battery together with the main breaker. The Raspberry Pi is powered by the battery via a step-down converter (Meanwell IRM-15-12). The MCB is a rare finding - unpolarized DC breaker rated at 40A/500VDC (Noark ExBP-H series).
Now I'm using all Chevy Volts modules, which gives me around 12-13 kWh usable capacity at a nominal voltage of 360VDC.

 

[Cheap 4-life]

I also love my Chevy volt batteries!
Yasko, looks good.
Question, you said you have 12-13kwh of usable capacity. I see 16kwh total capacity. How are you getting 12-13kwh of usable capacity. What’s your depth of discharge? What’s your top and bottom voltages?

 

[Bubba]

I to love the look of EV units or cells like the Leaf, but I don't find high voltage to be acceptable on a residential property. I don't think my insurance would cover me either.

Recently I started thinking about selling my 6000+ of the 18650 cells to get a Leaf setup. (located in SW Ontario).

 

[powertrack]

Cool project, will be interessted how you made the CAN Converter

 

[yasko]

@Cheap 4-life: I've done some more precise calculations, and with the current settings, usable capacity is around 11.8kwh. Here is the math:
These cells are at 86 % SOH (38.5Ah/45Ah), which gives around 13.7 kWh remaining capacity from the initial 16kWh. That is valid if we charge cell to 4.15V and discharge to 3.0V.
I'm using some lower levels - from 4.10V to 3.4V, which give us around 123.3Wh/cell or 11.8kWh for a whole battery. So that is 86% depth of discharge, which is maybe too aggressive. What are your top and bottom levels?

@powertrack What do you mean by "CAN converter"?
I'm using a Raspberry Pi with a two-channel CAN bus shield to handle CAN bus communication.
That shield gives me a two CAN interface named can0 and can1. The can0 connected to Chevy Volt BICM modules, and the can1 connected to the inverter BMS port. A small C program translates data from the can0 to the can1, according to inverter requirements. More on this later.
I've updated my previous post with an example of data that runs on the can1 interface.

 

[Cheap 4-life]

I have 12.4kwh of gen2 batteries. All of my batteries are 2017+ , all of them have less than 25,000 miles. I estimate them at (due to the year and mileage) 80% 9.9kwh max remaining of the original max 12.4kwh. That’s if I was to charge and discharge to max voltages. I actually charge to 4.07 and discharge to 3.56. That is roughly the cell voltages that the chevys gen2 bms followed. I am getting 6.5kwh (of usable power) at that voltage range from the original 12.4kwh. So I’m actually only able to use 52% of the original 12.4kwh that the batteries would have had when they were new.

If my batteries were new then i am supposed to get 77% usable capacity. From a complete 18kwh gen2 pack that would be 14kwh. If my 12.4kwh pack was new then 77% would be 9.6kwh. As I said I’m only getting 6.5kwh. Maybe if I stretched the voltage range a bit then I could get maybe another kWh. So 7.5kwh would be my max usable capacity that I can safely get from the 12.4kwh. 7.5kwh is 78% (close to the 80% I said above) of the 9.6kwh usable that I’d have if the batteries were new.

 

[Cheap 4-life]

The full gen1 packs are 17kwh and out of that there’s 11kwh of usable power when the batteries are new. Your batteries are from before 2015 so I’d expect some degradation. Maybe they were used in a vehicle?
So from your 16kwh you would have right at 10kwh of usable power if the batteries were from a 2021 vehicle and not used at all. I’d suspect from there age (older than 2015) that they have some degradation as you described when you said 86%. 86% of 10kwh that is usable from your pack if it was a new 16kwh pack would be 8.8kwh. 8.8kwh is what you should reasonably expect if your batteries indeed have 86% of new capacity. This is because you are only starting off with 10kwh max usable power from your 16kwh if they were new. This is why when you said 12+kWh I was wondering how this is so.
Sorry if all that’s hard to follow I was kinda doing the math and figuring it out as I was typing it.
Btw the gen2 full packs have 18.4kwh total and usable capacity of 14kwh
the gen1 full packs have 17kwh total and a usable capacity of 11kwh
The gen2 packs have 25% more usable capacity than the gen1 packs. This is most of the reason why I can get right at 7.5kwh from 12.4kwh of gen2 but from gen1 you could only get 8.8kwh from 16kwh.

 

[powertrack]

@Cheap 4-life: I've done some more precise calculations, and with the current settings, usable capacity is around 11.8kwh. Here is the math:
These cells are at 86 % SOH (38.5Ah/45Ah), which gives around 13.7 kWh remaining capacity from the initial 16kWh. That is valid if we charge cell to 4.15V and discharge to 3.0V.
I'm using some lower levels - from 4.10V to 3.4V, which give us around 123.3Wh/cell or 11.8kWh for a whole battery. So that is 86% depth of discharge, which is maybe too aggressive. What are your top and bottom levels?

@powertrack What do you mean by "CAN converter"?
I'm using a Raspberry Pi with a two-channel CAN bus shield to handle CAN bus communication.
That shield gives me a two CAN interface named can0 and can1. The can0 connected to Chevy Volt BICM modules, and the can1 connected to the inverter BMS port. A small C program translates data from the can0 to the can1, according to inverter requirements. More on this later.
I've updated my previous post with an example of data that runs on the can1 interface.

With CAN Converter I mean somehow an Gateway, translate protocol from CAN0 (your BMS) to CAN1 (Goodwe) , as you have done.
I think this Converter/Gateway is the Key point in many HV Battery Systems for the DIY Stuff... because so you can use HV Inverters without terrible modifications on hard and software

Maybe some short words:
I have already build up an HV DC Battery Back with an 500€ Infini Hybrid Inverter, in manual mode, the power electronic stuff is running, but the main problem for me is, I'm not able to get the softwarestuff running (More or less I have no software skills (absolutely basic)), when I'm looking to the Goodwe hybrid Inverters I think I will drop my design and switch to the goodwill, It has everything inside and quite cheap.
I'm using a complete Nissan Leaf battery pack (no special changes), if you are interested, see: HV Speichersystem im Selbstbau - Stromspeicher (Netzparallel) - Photovoltaikforum

if it would be useful for you: I have the possibility to get access to an BYD HV System, connected to a Fronius Symo Gen24, I could possibly do some packet sniffing.

powertrack

 

[prepared1]

Prepared1, did you get the gen1 Chevy volt batteries battery hookup just had for sale?

No, my batteries are almost all Samsung/A123/Toshiba. Battery hookup had pretty limited quantities of those Volt units...in fact, I was under the impression that the ones shown were the only ones. I could easily be wrong. Their deal where it is $350 shipping was a killer for me, unless you bought 2-4 of those modules, which ship for the same $350. That is why I'm waiting to jump on one of those military packs they had a few months ago, with A123 cells. I really like the Malibu packs, Kia Soul, etc. I did get a couple of those little 300 watt Panasonic jobbies with the cool metal case and handle, to make into a small portable powerpack.

It seems like like many other things, batteries are in short supply right now.

 

[Cheap 4-life]

No, my batteries are almost all Samsung/A123/Toshiba. Battery hookup had pretty limited quantities of those Volt units...in fact, I was under the impression that the ones shown were the only ones. I could easily be wrong. Their deal where it is $350 shipping was a killer for me, unless you bought 2-4 of those modules, which ship for the same $350. That is why I'm waiting to jump on one of those military packs they had a few months ago, with A123 cells. I really like the Malibu packs, Kia Soul, etc. I did get a couple of those little 300 watt Panasonic jobbies with the cool metal case and handle, to make into a small portable powerpack.

It seems like like many other things, batteries are in short supply right now.

My mistake, I was wanting to ask yasko