4-cell BMS - Revision history

Johu: Added github links

2024-05-27T09:05:32Z

Added github links

← Older revision		Revision as of 09:05, 27 May 2024
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	The master unit has two CAN busses that can be used for system integration. It continuously estimates vital parameters like SoC and SoH, calculates power limits etc. In electric vehicles it can control fuel gauges via a 2 channel analog output. Finally a relay can be used for basic charge or discharge control.		The master unit has two CAN busses that can be used for system integration. It continuously estimates vital parameters like SoC and SoH, calculates power limits etc. In electric vehicles it can control fuel gauges via a 2 channel analog output. Finally a relay can be used for basic charge or discharge control.

			Github Hardware: https://github.com/jsphuebner/bms-hardware

			Github Software: https://github.com/jsphuebner/bms-software

	== Wiring Diagram ==		== Wiring Diagram ==

Marcexec at 10:05, 14 June 2023

2023-06-14T10:05:56Z

← Older revision		Revision as of 10:05, 14 June 2023
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	</syntaxhighlight>All cell modules on all isolators enter update mode. Afterwards the isolators expect binary data on the console. 1 byte page number, 64 bytes page data, 2 bytes CRC16 xmodem over page num and page. After sending a page wait 170ms. If there is no response from any isolator continue with the next page. If there is, resend the page. After 56 pages the cell modules exit update mode and jump to the new firmware.		</syntaxhighlight>All cell modules on all isolators enter update mode. Afterwards the isolators expect binary data on the console. 1 byte page number, 64 bytes page data, 2 bytes CRC16 xmodem over page num and page. After sending a page wait 170ms. If there is no response from any isolator continue with the next page. If there is, resend the page. After 56 pages the cell modules exit update mode and jump to the new firmware.
			[[Category:BMS]][[Category:Battery]]

LRBen: Added annotated photo of v5.3 slave board. Replaced the previous slave board photo.

2022-02-12T22:23:24Z

Added annotated photo of v5.3 slave board. Replaced the previous slave board photo.

← Older revision		Revision as of 22:23, 12 February 2022
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	[[File:~~4-cell module~~.jpg\|~~alt=4-cell module~~\|~~thumb~~\|~~4-cell module~~]]		[[File:PXL 20220212 221048871.jpg\|thumb\|377x377px\|v5.3 slave board with annotations]]
	The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. It can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.		The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. It can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.

Johu: Updated to reflect current system design

2020-03-03T18:59:28Z

Updated to reflect current system design

← Older revision		Revision as of 18:59, 3 March 2020
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	[[File:4-cell module.jpg\|alt=4-cell module\|thumb\|4-cell module]]		[[File:4-cell module.jpg\|alt=4-cell module\|thumb\|4-cell module]]
	~~[[File:Isolator module.jpg\|alt=Isolator module\|thumb\|Isolator module]]~~		The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. It can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.
	The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. ~~Depending on the populated resistors it~~ can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.

	Its features are:		Its features are:
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	* 2mA balanced cell drain during operation		* 2mA balanced cell drain during operation
	* 50µA balanced cell drain in sleep mode		* 50µA balanced cell drain in sleep mode
	* 1-wire ~~bit-length-encoded~~ current mode communication		* 1-wire UART current mode communication, 10kbit/s
	The communication is terminated/translated via ~~an isolator~~ module~~. It translates the "proprietary" 1-wire protocol to a standard protocol, currently RS485~~. Its output connects the the first cell-groups positive terminal via a 1k resistor (Pin 3 of the 4-cell module) and the communication input. Its input connects to the last cell groups positive terminal~~, also via 1k resistor~~ and the communication output.		* Very low cost due to generic component use and low component count
			[[File:BMS Master Unit.jpg\|alt=BMS Master Unit\|thumb\|BMS Master Unit]]
			The communication is terminated/translated via at the master module. Its output connects the the first cell-groups positive terminal via a 220 Ohm resistor (Pin 3 of the 4-cell module) and the communication input. Its input also connects to the last cell groups positive terminal and the communication output.

	All communication that goes into the first module is forwarded in a daisy-chain manner out to the last module. Each cell module can see the communication stream of the modules BEFORE it but not the modules after it. Exception: address mode, discussed below.		All communication that goes into the first module is forwarded in a daisy-chain manner out to the last module. Each cell module can see the communication stream of the modules BEFORE it but not the modules after it. Exception: address mode, discussed below.

			The master unit has two CAN busses that can be used for system integration. It continuously estimates vital parameters like SoC and SoH, calculates power limits etc. In electric vehicles it can control fuel gauges via a 2 channel analog output. Finally a relay can be used for basic charge or discharge control.

	== Wiring Diagram ==		== Wiring Diagram ==
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	In run mode the module accepts the following commands		In run mode the module accepts the following commands
	* "Get Data X" : module X sends its 4 cell voltages and the temperature within the controller (cell group temperature)		* "Get Data X" : module X sends its 4 cell voltages and the temperature within the controller (cell group temperature)
	* "Shunt X Y": module X ~~sets its shunt target voltage to~~ Y~~+3000 mV~~. Returns Y for plausibility checking		* "Shunt X Y": module X enables shunts Y (bitmask). Returns Y for plausibility checking
	* "Get version X": module X sends its hardware and firmware version		* "Get version X": module X sends its hardware and firmware version
	* "Reset address": All modules reset their address and enter address mode		* "Reset address": All modules reset their address and enter address mode
	* "Calib X Y Z": module X adds Z to the the gain factor of channel Y. Returns the new gain factor. Z can be negative. Y can be
	** 0-3: low resolution voltage channels gain
	** 8-11: high resolution voltage channels gain
	** 16: temp sensor offset
	** 31: lock calibration to prevent unwanted changes during operation
	* "Update": All modules change to firmware update mode		* "Update": All modules change to firmware update mode

	=== Update mode ===		=== Update mode ===
	This allows updating the modules firmware via the existing 1-wire communication bus. The current version with 4k of flash memory expects 56 pages of 64 bytes each, prepended with the page number and terminated with the pages CRC16. The protocol is implemented in ~~a python script~~. If any module discovers a CRC error it sends a pulse onto the bus. The ~~isolator~~ then has to resend the page.		This allows updating the modules firmware via the existing 1-wire communication bus. The current version with 4k of flash memory expects 56 pages of 64 bytes each, prepended with the page number and terminated with the pages CRC16. The protocol is implemented in the master unit and the cell module firmware is embedded into the master units firmware. If any module discovers a CRC error it sends a pulse onto the bus. The master then has to resend the page.

	As we are planning to switch to the Attiny84 this would have to be changes to 120 pages. (The boot loader takes up 8 pages).		As we are planning to switch to the Attiny84 this would have to be changes to 120 pages. (The boot loader takes up 8 pages).

	== Isolator Command line interface ==		== Isolator Command line interface - deprecated! ==
	As already known from the inverter the isolator is controlled via a simple command line interface to carry out above operations. Since there can be more then 1 isolator on the RS485 bus each isolator is automatically assigned an address that has to be supplied to each command. This results in a hierarchical bus structure where the 1st module on the 1st isolator has address "1.1" and the yth module on the xth isolator has address "x.y".		As already known from the inverter the isolator is controlled via a simple command line interface to carry out above operations. Since there can be more then 1 isolator on the RS485 bus each isolator is automatically assigned an address that has to be supplied to each command. This results in a hierarchical bus structure where the 1st module on the 1st isolator has address "1.1" and the yth module on the xth isolator has address "x.y".
	Com speed is 115200.		Com speed is 115200.
Line 70:		Line 68:
	Lock calibration data of cell module x.y		Lock calibration data of cell module x.y
	cmupdate		cmupdate
	All cell modules on all isolators enter update mode. Afterwards the isolators expect binary data on the console. 1 byte page number, 64 bytes page data, 2 bytes CRC16 xmodem over page num and page. After sending a page wait 170ms. If there is no response from any isolator continue with the next page. If there is, resend the page. After 56 pages the cell modules exit update mode and jump to the new firmware.		<syntaxhighlight lang="Python" line="line">

	<syntaxhighlight lang="Python" line='line'>
	import serial		import serial
	import crc16		import crc16
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	page = page + 1		page = page + 1

	</syntaxhighlight>		</syntaxhighlight>All cell modules on all isolators enter update mode. Afterwards the isolators expect binary data on the console. 1 byte page number, 64 bytes page data, 2 bytes CRC16 xmodem over page num and page. After sending a page wait 170ms. If there is no response from any isolator continue with the next page. If there is, resend the page. After 56 pages the cell modules exit update mode and jump to the new firmware.

	~~== Plans ==~~
	~~To become compatible with Tom De Bree's "SimpBMS"~~ a ~~CAN~~ isolator is ~~planned~~. ~~It would operate more autonomous spitting out voltages and temperatures continuously~~ and ~~accepting shunt commands. Both should mimic some already existing BMS CAN protocol. The specialized commands can be implemented in which ever fashion~~.

Sonachan1: Updated the BMS wiring diagram

2019-11-25T19:22:28Z

Updated the BMS wiring diagram

← Older revision		Revision as of 19:22, 25 November 2019
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	== Wiring Diagram ==		== Wiring Diagram ==
	[[File:BMS Wiring Diagram.jpg\|none\|thumb\|600x600px\|Wiring Diagram]]		[[File:Huebner BMS Wiring Diagram.jpg\|alt=\|none\|thumb\|600x600px\|Wiring Diagram]]

	== Operation ==		== Operation ==

Sonachan1: Added the wiring diagram

2019-09-11T17:00:41Z

Added the wiring diagram

← Older revision		Revision as of 17:00, 11 September 2019
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	All communication that goes into the first module is forwarded in a daisy-chain manner out to the last module. Each cell module can see the communication stream of the modules BEFORE it but not the modules after it. Exception: address mode, discussed below.		All communication that goes into the first module is forwarded in a daisy-chain manner out to the last module. Each cell module can see the communication stream of the modules BEFORE it but not the modules after it. Exception: address mode, discussed below.

			== Wiring Diagram ==
			[[File:BMS Wiring Diagram.jpg\|none\|thumb\|600x600px\|Wiring Diagram]]

	== Operation ==		== Operation ==

Johu: /* Update mode */

2019-07-30T08:47:20Z

Update mode

← Older revision		Revision as of 08:47, 30 July 2019
Line 39:		Line 39:

	=== Update mode ===		=== Update mode ===
	This allows updating the modules firmware via the existing 1-wire communication bus. The current version with 4k of flash memory expects 56 pages of 64 bytes each, prepended with the page number of terminated with the pages CRC16. The protocol is implemented in a python script. If any module discovers a CRC error it sends a pulse onto the bus. The isolator then has to resend the page.		This allows updating the modules firmware via the existing 1-wire communication bus. The current version with 4k of flash memory expects 56 pages of 64 bytes each, prepended with the page number and terminated with the pages CRC16. The protocol is implemented in a python script. If any module discovers a CRC error it sends a pulse onto the bus. The isolator then has to resend the page.

	As we are planning to switch to the Attiny84 this would have to be changes to 120 pages. (The boot loader takes up 8 pages).		As we are planning to switch to the Attiny84 this would have to be changes to 120 pages. (The boot loader takes up 8 pages).

	== Isolator Command line interface ==		== Isolator Command line interface ==

Johu at 08:43, 30 July 2019

2019-07-30T08:43:59Z

← Older revision		Revision as of 08:43, 30 July 2019
Line 1:		Line 1:
	[[4-cell module.jpg\|alt=4-cell module\|thumb\|4-cell module]]		[[File:4-cell module.jpg\|alt=4-cell module\|thumb\|4-cell module]]
	[[File:Isolator module.jpg\|alt=Isolator module\|thumb\|Isolator module]]		[[File:Isolator module.jpg\|alt=Isolator module\|thumb\|Isolator module]]
	The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. Depending on the populated resistors it can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.		The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. Depending on the populated resistors it can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.

Johu at 08:43, 30 July 2019

2019-07-30T08:43:42Z

← Older revision		Revision as of 08:43, 30 July 2019
Line 1:		Line 1:
	4-cell module.jpg\|alt=4-cell module\|thumb\|4-cell module]]		[[4-cell module.jpg\|alt=4-cell module\|thumb\|4-cell module]]
	[[File:Isolator module.jpg\|alt=Isolator module\|thumb\|Isolator module]]		[[File:Isolator module.jpg\|alt=Isolator module\|thumb\|Isolator module]]
	The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. Depending on the populated resistors it can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.		The 4-cell BMS owes its name to the fact that every cell module can monitor and balance up to for Lithium cells. Depending on the populated resistors it can be used for LiFePO4 (3.3V) or NMC (3.7V) cell chemistries.

Johu: /* Isolator Command line interface */

2019-07-26T14:00:00Z

Isolator Command line interface

← Older revision		Revision as of 14:00, 26 July 2019
Line 44:		Line 44:

	== Isolator Command line interface ==		== Isolator Command line interface ==
	As already known from the inverter the isolator is controlled via a simple command line interface to carry out above operations. Since there can be more then 1 isolator on the RS485 bus each isolator is automatically assigned an address that has to be supplied to each command. This results in a hierarchical bus structure where the 1st module on the 1st isolator has address "1.1" and the ~~Nth~~ module on the ~~Mth~~ isolator has address "M.N".		As already known from the inverter the isolator is controlled via a simple command line interface to carry out above operations. Since there can be more then 1 isolator on the RS485 bus each isolator is automatically assigned an address that has to be supplied to each command. This results in a hierarchical bus structure where the 1st module on the 1st isolator has address "1.1" and the yth module on the xth isolator has address "x.y".
	Com speed is 115200.		Com speed is 115200.
	get x.y		get x.y