Simp BMS

[tom91]

I have been quite actively developing a system that would allow the reuse of existing bms slaves from OEM vehicles, as documented on DIYelectricCar forum.

This has been received very well, especially by the solar storage community. All the coding is open sourced, as this allows others to add more OEM systems into this system and allow more and more things to be reused.

The manual on what the functions are so far: https://github.com/tomdebree/SimpBMS

The sales thread : viewtopic.php?f=12&t=130

Currently supported slaves:
-Tesla Model S/X https://github.com/tomdebree/TeslaBMSV2
-Tesla battery modules used in other OEM cars https://github.com/tomdebree/TeslaBMSV2
-VW E-Golf and GTE (no balancing currently) https://github.com/tomdebree/VW-bms
-Mitsubishi Outlander https://github.com/tomdebree/OutlanderPHEVBMS
-Mitsubishi Imiev https://github.com/tomdebree/ImievBMSV2
-Gen 1 Volt/Ampera https://github.com/tomdebree/AmperaBattery
-BMW I3 https://github.com/tomdebree/BMWI3BMS
-BMW PHEV https://github.com/Tom-evnut/BMWPhevBMS

Currently supported chargers:
-Victron ecosystem
-SMA LV ecosytsem , hv underdevelopment
-Chevy bolt charger
-Coda charger
-Brusa NLG5xx
-Elcon
-Eltek

[arber333]

Hi
One of desirable things would be to add a second CAN transmitter.

I would use Volt/Ampera cells with it, but also i would like to use CAN operated charger and DCDC converter. The original CAN inside battery is using 125kbps comms. My charger and DCDC are using 500kbps comms. Those lines cant mix then.
I tried to convert my charger to 125kbps religion but it is a stubborn mother...
Is it possible i could just add one more CAN module to BMS like this? https://www.electronicshub.org/arduino- ... -tutorial/
Would you support it in software?

Or do you have a different idea?

tnx

Arber

[tom91]

There is a two can bus version coming using teensy 3.6

[arber333]

There is a two can bus version coming using teensy 3.6

Wicked!
Count me in for one BMS with 2x CAN I/Os!

I have seem you use usart LCD with your BMS. Is that Nextion LCD? Does it show cell values? Can we use touch?
You have some photos?

tnx

[johu]

Is the serial connection via RS485?
I'm thinking to use it as a master for my homebrew BMS. What do you think?

[tom91]

Its just using the teensy onboard serial.https://www.pjrc.com/teensy/td_uart.html

The nextion display is there to show pack stats, it does not show all cell voltages as that is too much.

The interface is only one way, as in the bms populates the info on the display and the display does not send anything back.

Attached the page layouts below.

[arber333]

Is system capable of showing the lowest and highest cell value and both positions? This would be great for cell maintenance.

Could you add to your new BMS master optional Volt/Ampera DCDC CAN signal?
I imagine it would work like so... When 12V from ignition is present one output signal connects 12V to DCDC and signals correct ID and msg on 500kbps CAN line.
When car would be stopped enable line is shutoff and BMS stops transmitting this msg.
Also when 230Vac is sensed BMS starts to output charger ID and msg and enable signal is disabled by relay bridge. So that i wouldnt driveoff with cable in socket .

[tom91]

Charging is already done when you drive an input high, it sends the appropriate can bus and drives a relay output.

I need to find some time to make the new design, currently really busy at work. Got so many nice projects going on there.

[joromy]

I think there is a small error in your manual and wiring example.

In wiring example conn5 pin 1 and 6 are "key ON" "CHG AC present"
In table for conn5 pin 1 and 2 have the same function.

[tom91]

Correct the table needs to match the diagram.

Connector 5
Pin 1- Key ON
Pin 6 - CHG AC present

[Oskar]

Hi
How about Hyundai/Kia? I have a battery pack from Ioniq that I intend to use in my conversion of a 64 VW Beetle. It would be nice if I could use the OEM slaves.

[tom91]

If you know if it really uses a slave and not a single large BMS module like a leaf.

I would require someone to give me the info on the canbus communication required and I can add it in. Or someone to pay for me to reverse engineer it, this would require access to the hardware and possibly a car.

[Oskar]

There are ten CMU's and one management unit inside the pack. I will do my best to find a car and get some canbus data out of it. Thanks for now. Here is some photos of the hardware.

https://photos.app.goo.gl/Uke6M8CSPGU5axCz7

[tom91]

Do you have any wiring information? Or any detailed info on the slaves board ICs?

[Oskar]

I could try to figure out the wiring.

[tom91]

looks like it is this chip : https://www.maximintegrated.com/en/prod ... ml/tb_tab0

So the daisy chaining would happen via UART style comms.

Data sheet on it : https://media.digikey.com/pdf/Data%20Sh ... ug2018.pdf

[joromy]

tom91
I now have the Simp BMS on all time 12v. The LEM current sensor is only ON in Drive and Charge mode.
That saves me 40mA on the 12V standby current.

But then i sometimes get "nanmA" on the can-bus current, and have to restart.
Is there some way to avoid this?

Did some strange measurement:
Simp BMS use 53mA (+40mA for current sensor)
and 61mA without the current sensor.

????????

[tom91]

That is wierd,I will do some testing on the power consumption with and without the current sensor. I can look at having current measurement only take place when in Drive or Charge mode.

[tom91]

Got implementation for the use of a IsaScale IVT sensor working.

https://www.isabellenhuette.de/en/preci ... vt-series/

I love these sensors, might even look at gettng some of those to sell to other users.

Shunt based measurement so it is accurate from 1mA upto 1kA just what an EV wants.

I now have the Simp BMS on all time 12v. The LEM current sensor is only ON in Drive and Charge mode.
That saves me 40mA on the 12V standby current.

Still researching the Teensy 3.2 sleep possibility and other power reduction options.

[joromy]

Still researching the Teensy 3.2 sleep possibility and other power reduction options.

It would be nice to be able to shut off current sensor and power it from key on/AC present.
The same for power to the BMB.

Now the BMS will not resume properly if I shut down power to current sensor and BMB.

And setting the Teensy in sleep mode, wake it up at "key on" and "AC present" would give almost no current draw.

Have searched the net for normal current draw in a car:
"The acceptable current draw should be around 0.03Amps.
If that can't be achieved upto 0.075-0.1 can be acceptable if the vehicle is driven most days."

[tom91]

That is wierd,I will do some testing on the power consumption with and without the current sensor. I can look at having current measurement only take place when in Drive or Charge mode.

I have tried to see if I can realistically put the teensy into sleep. Not really happening as well as you would hope for some reason I cannot really get it below 25mA.

So I will now look at improving start up times to allow it just to be power cycled.

[joromy]

I have tried to see if I can realistically put the teensy into sleep. Not really happening as well as you would hope for some reason I cannot really get it below 25mA.

So I will now look at improving start up times to allow it just to be power cycled.

You just convinced me to have power on all time.
Wouldn't power cycling loose (Ah) SOC, or is there a way to save it?

Having Teensy on all time, and turning off BMB's and CAN current sensor, is not working. (get "nan" on current sensor)
Is there a way to have It resume the CAN (current sensor) and comm. to the BMB's??
This would be a very god start.

Looks like getting the Teensy to low power sleep is possible, in theory.....

[tom91]

I was getting 25mA with just the teensy and using some example sketches to put it to sleep.

Will have a go at saving the SOC.

[bulletbug]

tom91 I have a Gen 1 battery pack out of a Chevy Volt. I have the master and slave units for the BMS. I'd like to understand how to use the simpbms to manage these. I've seen the manual reference the contents of the purchased kit. Is there an existing webshop where I can buy this kit?

[joromy]

Is there a deadzone in the current (ah) counting.
If I have my car standing on battery heating, there is about 300-600mA draw.
But the ah counter is not changing.

Is this deadzone set to high?
The CAB sensor has almost no error at zero current, mostly shifting between -0.99mA and 1mA.