openinverter forum

Getting started on this project, grabbed an inverter from the junkyard for $100, and I'm excited to use it in my prius.


I'm going to install it in the back compartment above the spare tire and next to the traction battery, or maaybe on the outside under the car next to the spare tire well and above the plastic paneling, we'll see how it works out.

The plan for the electronics is to actually replace the lower inverter board with an openinverter board, since I won't be using the AC compressor inverter, or the DC/DC 200v->14v converter down there. I'll route the cables through the internal opening up to the upper chamber, so the entire thing can be sealed up except for the 12v, 200v, and two inverter outputs. You can see the opening in the top right corner of the image here:


I'm not totally sure what I'll do for heat dissipation, and I'm not sure how much heat will need to be dissipated. I kinda want to get away with just pumping the coolant around in a loop without a dedicated radiator, but I don't know if that'll fly. I saved some hoses and 12v pumps from the scrapyard also.

For outputs, I'm interested in some 110V 60Hz AC and maybe even a split phase 220V 60Hz output because I think it'd be cool to run a welder. I'll have to design an output filter to adsorb the high frequency switching energy, maybe with the inductor and cap from another prius or something else, we'll see what the math says. I think for a split phase output, I might need a center tap transformer? Or maybe just 4 phases of the inverter hooked in a split configuration. Haven't totally planned that out yet.

The first step I think will be to reproduce the work of johu, so I'm going to have the prius gen 2 boards made using the gerbers and BOM from the repo
https://github.com/jsphuebner/inverter-hardware
I'd love access to the eagle schematic files for the gen 2 board

and then flash it with this version of the firmware and go from there.
https://github.com/jsphuebner/stm32-island

I think I'll have to move to an STM32 with two advanced timers for the custom board to enable me to run all 6 phases of the inverter, instead of just the MG2 outputs.

Any thoughts on that, or heat dissipation, other aspects of this project would be appreciated, since I'm completely new to the openinverter project.

I've seen a few members looking for the gen2 Prius board I think we should have a moq batch made and share.

I think people don't ascribe enough weight to just how slowly interest percolates down through the DIY chain. Damien first reverse-engineered the Prius Gen 2 back like, 7 or 8 years ago. Johannes had been selling his board for like, 5 years? WITH a full demo of it (sort of) working on an entirely documented project. And still sales were almost nothing, and overall was probably a flop for the time he put in.

A couple people in the community got their cars working with it.

Greg did his Rabbit 2 (?) years ago with it.

But for the lowest common denominator of people who'd attempt it, (versus nicer hardware for more money and better performance) it's still intimidating to approach.

And yet people are still now starting to ask about starting a project with it.

...

I'd love to see your design for doing something off-grid with it. It'll be the cheapest way to get a high power inverter I'd hope. I have an extra inverter lying around and would like to add solar sooner or later here.

Since I might do another Prius project myself I will order a few boards. I have also updated the design a bit, it now has native control of the CSDN signal that shuts down the buck/boost converter at startup. I have ommitted the ground pin on the inverter side connector to make room for that.

So you have paid 100$ for the inverter. How much do you think the control board is going to cost? I am sure buying a hybrid solar inverter is more cost effective. I don't mean to discourage you. Only curious about your logic.
For 300$ I bought an all in one solar inverter that can take 6kw/450v from solar input. This goes toward 6kw output into 230v AC and 48 (62v max) DC battery. Can do both at once. What is your reasoning here? Is it about having full control of the device, power output, mobile usage or reliability?

But if anyone is making 2 motor inverter controller then I'm in.

I could just buy an inverter, but I was pretty excited by johu's work with the salvaged inverter. I think it'd be cool to develop a drop in board for others to use in the future that allows use of all 6 major phases of the inverter. I'm also just interesting in getting in a power electronics project, and this seemed pretty achievable given the foundations already accumulated here and the community.

I'm still brainstorming what components could be useful for filtering the pwm modulated outputs. Maybe the inductor and capacitor from another inverter like this one, or some other readily available components.

0tik wrote: ↑Sat Mar 21, 2026 10:06 am For 300$ I bought an all in one solar inverter that can take 6kw/450v from solar input. This goes toward 6kw output into 230v AC and 48 (62v max) DC battery.

New? Used? What model? I was looking around briefly, but didn't see something that caught my attention.

johu wrote: ↑Sat Mar 21, 2026 7:42 am I have also updated the design a bit

Are the updates/cad files available on github? I'd love to take a look.

MattsAwesomeStuff wrote: ↑Wed Mar 18, 2026 3:19 am I'd love to see your design for doing something off-grid with it. It'll be the cheapest way to get a high power inverter I'd hope. I have an extra inverter lying around and would like to add solar sooner or later here.

Yeah, I think something like that would be awesome. I feel like it should be pretty doable. I'm a bit unfamiliar with solar setups, what kind of conversions do you need for something like that?

asphaltPhilosopher wrote: ↑Sat Mar 21, 2026 11:19 pm
New? Used? What model? I was looking around briefly, but didn't see something that caught my attention.

https://pl.aliexpress.com/item/10050115 ... 0653111313

I created a falstad simulation so we can test out different filtering components depending on what's handy.

For testing I chose some values that give a critical damping of the filter with an 18ohm load, and a resonant frequency in the logarithmic center of 60Hz and 8.8kHz, which gave
3.7mH
13uF

https://www.falstad.com/circuit/circuit ... 0jgAgIYIAA



Some references for making filter calculations given a single ended LC filter:
f = 1/(2pi*sqrt(LC))
Q = R sqrt(C/L)

f = sqrt(60Hz * 8.8kHz) (for an example lowpass frequency)
Q = 1/sqrt(2) (for critical damping)

(is there some kind of math script we can use?)

Any ideas on what readily available components we could use to construct this filter or one with some other values for f, Q, L, and C would be great. I think more inductance is better than less.

Another part that will be important will be some kind of feedback to maintain a constant voltage on the output as the load varies. Without that, the voltage does change pretty significantly. This happened in the demo video, and in this simulation, possibly for different reasons.

It's back: https://openinverter.org/shop/index.php ... duct_id=68

Because you name yourself a philosopher, i would like to ask what is the world point of view for this project.
You write on your own that you have to develop some boards and things like this. This does not seem to get a productive output for anyone else from the user point of view.

Your goal:

asphaltPhilosopher wrote: ↑Mon Mar 16, 2026 6:09 pm I'm interested in some 110V 60Hz AC and maybe even a split phase 220V 60Hz output

This is something you can in general reach by fixing broken stuff. Fixing broken stuff would help to reduce the need of producing something new.
There are many pure sine wave DC to AC inverters out there that broke. You can get a broken one and fix it. You are reaching your goal and all normal DC to AC inverters are build to not require a fluid cooling loop you seem to not want to have.
When you fix 5 broken ones, you can sell them to other people. Those general inverters are something many people use.
There are some more modern AC to DC chargers in cars that support V2L. The newest Mitsubishi chargers have V2L. To my knowledge no one have figured out how to use the new Mitsubishi chargers for V2L.
The MG chargers also have V2L https://openinverter.org/forum/viewtopic.php?t=5950 https://openinverter.org/forum/viewtopi ... v2l#p88081

hey guys, don't discourage experiments. Who knows what it's good for

johu wrote: ↑Mon Mar 23, 2026 11:00 am It's back: https://openinverter.org/shop/index.php ... duct_id=68

hahaha

hjdlsnbc wrote: ↑Mon Mar 23, 2026 4:26 pm There are some more modern AC to DC chargers in cars that support V2L. The newest Mitsubishi chargers have V2L. To my knowledge no one have figured out how to use the new Mitsubishi chargers for V2L.
The MG chargers also have V2L https://openinverter.org/forum/viewtopic.php?t=5950 https://openinverter.org/forum/viewtopi ... v2l#p88081

Thanks for the references, I was looking for a common term for this in hybrid automotive, V2L (vehicle to load) seems like the one. With that I should be able to find more info and parts relevant to this project, even to your point about possibly fixing or open sourcing some of those existing V2L boards. Still gotta read more prior work from the community along these lines.

In any case, I'll keep working towards the original goal with this inverter. I'm excited by the pedagogical opportunity it's given me so far. Thinking about making a large inductor using discarded microwave oven cores, or maybe winding a toroidal inductor.

I keep thinking about the thermal mass of the aluminum case, and whether it's really important to have the liquid cooling or not. Maybe monitoring the temperature readings from the inverter, I can see how much heat is really generated.

Anyway, tomorrow I'll be powering up the 12v side and playing with the control lines, following in the footsteps of those before, just to get my bearings.

johu wrote: ↑Mon Mar 23, 2026 11:00 am It's back: https://openinverter.org/shop/index.php ... duct_id=68

Cool, exciting. Is there a chance you'd sell me an unpopulated PCB?

Just found out about the V2x section of the forum, I had no idea what that meant before haha, Excited to read about what people have been up to and get inspired for this project

asphaltPhilosopher wrote: ↑Wed Mar 25, 2026 8:59 amCool, exciting. Is there a chance you'd sell me an unpopulated PCB?

Johannes: "Hey I developed this board and ran off a bunch of copies. Who wants them?"

Almost everyone: *crickets*

Johannes after several years: "Hey so I've stopped re-ordering these boards, just so you know."

Several people: *Complaints*

Johannes: "Okay so I made more boards I guess, you can buy them now and I even added some features."

You: "Can you make a custom board for me specifically, that's even cheaper, and where you don't even cover your costs?"

Johannes: *glares*

Hey hey no need to be so passive aggressive. If I manage to run the board with mg1, I'll order second one for mg2 in parallel. Just give me a couple of months, I swear!

...I won't blow anything up by connecting mg1 and mg1 inverter to the control board... Right...?

Anyhow, a few boards are now on the shop: https://openinverter.org/shop/index.php ... ry&path=61

Here are the changes: P2.12 is now connected to CSDN and no longer serves as a GND pin. It activates the converter when software enters run mode
CPWM is now pulled up by default