BMS for 48V to 400V lithium-ion battery pack

Batteries, Chargers, and Battery Management Systems.
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ENNOID   10 mW

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BMS for 48V to 400V lithium-ion battery pack

Post by ENNOID » Feb 20 2018 8:22pm

Hi,

I'm looking for an open source BMS (Battery Management System) which would allow me to develop my own electric vehicle lithium-ion battery pack for voltages range from 48V and up to 400V.

The problem I am encountering right now is the lack of any medium voltage open source BMS with advanced functions available on the market as far as I know. After looking on the internet for documentation and related projects, the closest thing (open source) I have been able to find, is this very cool open source 12 cells BMS :

- https://github.com/DieBieEngineering/DieBieMS

This BMS has several interesting features that I am looking for:
- STM32 MCU configurable through USB with the user interface developed for the VESC-project
- CAN Bus
- Integrated SD card for DATA logging
- Integrated pre-charge and charge/discharge enable circuit.

Despite this, the rest of this BMS is limited to 12 cells /approx 48V and is using an outdated LTC6803 integrated chip.

Considering the voltage limitation of the DieBieMS, I am tempted to start the development of a similar BMS, based on it, but capable of handling a 400V/96S cells battery pack. For this, a Master and some daisy-chained slaves boards will be required instead of just one single board. The 16 cells "bq76PL455" from TI seems to be a better choice compared to the LTC6803:

- www.ti.com/lit/ds/symlink/bq76pl455a-q1.pdf

So far, I just started the schematics on Kicad ... ( after all, I have a family to take care of, and a full time job + side business, but I still have some time somewhere for this kind of project)

The project files are available on github at :
https://github.com/EnnoidMe/ENNOID-BMS

Just for getting some attention, here is a related photo of a well documented TI evaluation BMS board that I would like to copy and operate with an STM32 MCU + some add-ons:
Image


Does some people here are interested for such a system in the open source ecosystem? Suggestions and ideas are very welcome :D


Thanks
Last edited by ENNOID on Jul 15 2018 7:06am, edited 1 time in total.

ENNOID   10 mW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by ENNOID » Feb 23 2018 11:35am

After looking on the web I found those threads related to BMS:

- viewtopic.php?f=14&t=63863
The part used has been discontinued... so that killed the project.

Another user from previous thread listed above "methods" started a thread about the use of an up-to-date LTC6811:
- viewtopic.php?f=14&t=88358#p1288949
I personally think this chip is worth to look at, similar to TI bq76PL455, but only 12 cells capability instead of TI's 16 cells, for almost the same price tag. So I still think TI IC is a better choice... ( cheaper and less components for the same pack voltage...)

Another similar approach with outdated LTC6802, but only slave board:
- https://github.com/rickygu/openBMS
Project is quite old and no development since 2014...

Another semi-open source BMS far more advanced and maintained also based on LTC6811 and STM32 is this one:
- https://www.foxbms.org/typo3/index.php?id=4

This foxBMS is exactly what I was looking at and is nearly completed :D
Last edited by ENNOID on Jul 15 2018 7:05am, edited 1 time in total.

ENNOID   10 mW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by ENNOID » Feb 23 2018 3:51pm

This www.foxBMS.org project is badass:

Image

ENNOID   10 mW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by ENNOID » Feb 24 2018 4:26pm

After a thorough inspection of this "FoxBMS", I do really see "german engineering" in this project... "system is over-engineered" :roll:

The redundancy and safety is too much implemented in the hardware. I think their approach is just too expensive. (cells are monitored by two costly IC and two MCU for ensuring safety)
Last edited by ENNOID on Jul 15 2018 5:45pm, edited 1 time in total.

ENNOID   10 mW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by ENNOID » Jul 13 2018 1:28pm

So far, it seems that I am alone in this thread. I haven't put much effort so far in this project anyway.

I now bring the fact that I just realized how the development board DC2350A-B and the related DC2026 control board developed by analog device seems to offer a good alternative for developing a proper BMS. It seems like a better starting point than the other development boards.

It is equipped with an LTC6813 which is a next gen IC capable of monitoring & balancing up to 18 cells (72V) with a minimal external circuit. It can communicate through an ISOSPI interface which is apparently way more reliable than what TI is offering.

See doc:
http://www.analog.com/media/en/dsp-docu ... 2350AF.PDF

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fechter   100 GW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by fechter » Jul 13 2018 2:29pm

There isn't much around that can do over 20s cells. Most of them are very expensive. If you look around on DIY Electric car you can probably find various approaches to the problem. https://www.diyelectriccar.com/

Some ES projects:
Speedict viewtopic.php?f=14&t=73354
Tiny BMS viewtopic.php?f=31&t=78552
Bluetooth BMS viewtopic.php?f=14&t=88676&p=1386696&hi ... o#p1386696
Adaptto viewtopic.php?f=31&t=58190&hilit=adaptto

I like the TI chip. There should be a way to daisy chain 16s modules to accommodate higher cell counts.

Way back when, I designed and built my own BMS for LiFePO4 cells, since there was practically nothing on the market at the time. It was good clean fun and I did finally make some boards that worked but it was WAY too much work and too time consuming. Nowadays, I look for inexpensive off the shelf boards that I can combine or modify to meet my needs rather than building from scratch.
"One test is worth a thousand opinions"

c10yas   1 µW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by c10yas » Dec 13 2018 2:42pm

Hey,
I got linked here from the ennoid-bms git. I'm designing a BMS for the FSAE competition based on the LTC6813 with reliability and low cost in mind. We're in the process of completing testing of the design and would love to share our work if it helps progress this project. Linked below is the git repo where we have the designs. The BMS stuff is being designed in Altium, but Altium has a free schematic viewer and I'd be happy to export it to kicad when we're done developing, I apologise for the badly documented git in advance
https://github.com/Illini-Formula-Elect ... Slave_2019

Chai

ENNOID   10 mW

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Re: BMS for 48V to 400V lithium-ion battery pack

Post by ENNOID » Dec 16 2018 12:16pm

Hi,

Thanks for sharing.
I cloned the complete git repository and had a quick look on the project with altium and eagle this morning.

one interesting thing I observed so far:

-one of the two ltc6813 is used only for temperature monitoring. Maybe it was easier to implement it this way. On my side, I was thinking doing it with only one ltc6813 through the use of the 9 gpio for temp measurement(one temp sensor between 2 cells or with a mux for 18 temp sensor). Is there any specific reason which explain the way your team implemented it throught a dedicated ltc6813?

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