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Product Overview

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BMS Battery management system

EVLithium BMS

Programmable EVLithium EBS-BMS Functions & Settings

Introduction

The programmable E-Bike Smart BMS (EBS-BMS) applies to superpower E-bike or E-motor which are equipped with a li-ion battery packs using less than 24 cells in series. (≤24s and any number of parallel cells).

The EBSBMS uses Linear Technologies battery management chip LTC6803,and microprocessor to achieve high accuracy, stability and safety.

Features

· supports 4-24s Li-ion battery pack,max 100V

· controls max.30A charging current, no limit discharging current

· controls E-bike electric lock (e-lock for short below), control E-bike throttle

· balances passively max 23 cells simultaneously at max. 200mA bleeding current

· monitors max. 4 external temperatures and 1 internal temperature

· monitors charging current with built-in sensor (+-50A) and discharging current with external sensor (+-200A/400A)

· supports 2.8inch LCD display

· includes professional PC software for parameter setting via TTL-USB adaptor cable

The BMS does:

· monitor all cell voltages V_cell

· monitor the battery pack current I_bat

· monitor battery pack and BMS temperature T_pack(4 channels) and T_sys (1 channel)

· SOC automatically learning and calculation

depending on the parameter settings the BMS will:

· detect and handle alarming situations (OV, UV, OC, UT, OT) by disconnecting e-lock/throttle or charger

· detect and handle charge and discharge limits of the battery pack

· detect unbalanced cells and control bleeding

	EVLithium EBS-BMS (Smart BMS for E-bike Throttle Control)
battery pack configuration	4-24s
DCHG current handling capacity	nominal: no limit (Choose appropriate CS)
CHG current handling capacity	max continuous: 30A
supply voltage	10V-100V for 4-24S
passive cell balancing	200mA,,max 23 cells simultaneously
SOC (calculated)	accuracy ±2.5% over one cycle
V_cell measurement	resolution 5mV, accuracy ±0.2%
current measurement	Internal CS for charging ±50A ±2.0%
current measurement	external CS for discharging, ±100 - 600A ±2.0%
supply current	20mA normal(e-lock is on) 0mA standby(e-lock is off)
communication	TTL-USB for PC and LCD
throttle control	PWM 5kHz, for clamping Hall element throttle signals 1-4V
auxiliary control	Cool and heat control signal (opto coupled open collector)

About supply current

· when customers turn off e-lock,BMS will also be turned off and no power consumption any more

· when customers forget to turn off e-lock(e-bike is no discharging and charging),BMS will be alarm
when UV(will not be turn off e-lock and throttle at this situation).BMS will turn off e-lock and throttle
until the battery pack is deeply lack of electricity

· When charger on, BMS will open to normal state and check the voltage of cells,if cells are under
CHG_Recover,

the e-lock will be automatically on and begin charging.(not all the chargers.)

Processing Logic

States (For charging)	CHG FET
V_cell>= CHG_Limit	OFF
V_cell<=CHG_Recover	ON
Over T_pack	OFF
Over T_pack Recover	ON
Over T_sys	Keep original state
Under T_pack	OFF
Under T_pack Recover	ON
Over Charging I_bat	OFF and Recover after 3 min
Plug on charger when e-lock is off	V_cell>= CHG_Recover OFF V_cell<= CHG_Recover On,e-lock on

sp;�ns��;�ging, ±100 - 600A ±2.0%

supply current

20mA norma (e-lock is on)

0mA standby (e-lock is off)

communication
TTL-USD for PC and LCD

throttle control

PWM 5kHz, for clamping Hall element throttle signals 1-4V

auxiliary control

Cool and heat control signal (opto coupled open collector)

States (For discharging)	E-lock and Throttle
V_cell<= DCHG_Limit	OFF
V_cell>=DCHG_Recover	ON
Over T_pack	OFF
Over T_pack Recover	ON
Over T_sys	Keep original state
Under T_pack	OFF
Under T_pack Recover	ON
Over Discharging I_bat	OFF and Recover after 5 min

Opto-coupler switch

Opto-coupler switch is in P8.

Discharging on, DCHG opto LED ON.
Current will be permitted between DCHG-A&DCHG-B.

Charging on.CHG opto LED ON.
Current will be permitted between CHG-A&CHG-B.

PWM

PWM State

When battery is in lower power state,signal of throttle controller will be changed by BMS.

When battery is in normal state,voltage of throttle in and throttle out are the same.

When battery is in lower power state,output signal will be 50% duty ratio modulated by

PWM signal in order to let output power reduce to 50%.Recuperation Current

BMS has two current sensor.One is the internal CS(current sensor) to monitor charging current.

The other is the external CS to monitor discharging current.Besides that,external CS can also

monitor recuperation current.This kind of CS is the two-way current sensor.When e-bike is downhill

or braking,recuperation current will be monitored and BMS will calculate this part of current to SOC.

(In general,customers use 100BT or 200BT external SC,so if recuperation current is too small,CS

can not monitor and BMS will not be calculate it to SOC.)

8. BAT-, 2. CHG-, 3. LCD, 4.Temperature sensor (4 channels), 5. External Temperature sensor

9. Cell 13-24 monitoring/bleeding (No.2 JST 18pin), 7. Cell 1-12 monitoring/bleeding (No.1 JST 16pin),

10. Buzzer, 9. TTL-USB, 10 Throttle/E-lock connector, 11. firmware update

P5
P5-1	B-
P5-2	B-
P5-3	B1+
P5-4	B2+
P5-5	B3+
P5-6	B4+
P5-7	B5+
P5-8	B6+
P5-9	B7+
P5-10	B8+
P5-11	B9+
P5-12	B10+
P5-13	B11+
P5-14	B12+
P5-15	B12+
P5-16	NC

P6
P6-1	B13-
P6-2	B13-
P6-3	B13+
P6-4	B14+
P6-5	B15+
P6-6	B16+
P6-7	B17+
P6-8	B18+
P6-9	B19+
P6-10	B20+
P6-11	B21+
P6-12	B22+
P6-13	B23+
P6-14	B+
P6-15	B+
P6-16	NC
P6-17	NC
P6-18	NC

P7
P7-1	+5V
P7-2	HALL
P7-3	GND
P7-4	NC

P1
P1-1	NTC1+
P1-2	NTC1-
P1-3	NTC2+
P1-4	NTC2-
P1-5	NTC3+
P1-6	NTC3-
P1-7	NTC4+
P1-8	NTC4-

P2
P2-1	+5V
P2-2	GND
P2-3	LCD_DATA
P2-4	LCD_CLK
P2-5	LCD_CS
P2-6	LCD_RES
P2-7	LCD_BL+
P2-8	LCD_BL-
P2-9	+3.3V
P2-10	BUTTON

P4
P4-1	NC
P4-2	NC
P4-3	NC
P4-4	NC
P4-5	NC
P4-6	NC

P8
P8-1	ISO_VCC
P8-2	Throttle In
P8-3	Throttle Out
P8-4	NC
P8-5	ISO_GND
P8-6	NC
P8-7	DCHG-A
P8-8	DCHG-B
P8-9	CHG-A
P8-10	CHG-B
P8-11	LOCK_IN
P8-12	LOCK_OUT

P3	USB Connector to PC

N5	B-
N6	CHG-

connection / power-up sequence:

1. connect BAT- power cable

2. connect CHG- power cable

3. connect LCD, temper sensors, switch

4. connect

No.1 JST-connector of battery test lines which starts with cell1 V- (which is same as BAT-)

5. if there are more than 12 cells connect second JST-connector of battery test lines which ends with the last cell + which is same as BAT+ (e.g. V20+ for a 20s pack)

6. turn on BMS switch

disconnection / power-down sequence

1.turn off BMS switch

2. if there are more than 12 cells disconnect second JST-connector of battery test lines which ends with the last cell + which is same as BAT+ (e.g. V20+ for a 20s pack)

3. disconnect first JST-connector of battery test lines which starts with cell1 V- (which is same as BAT-)

4. disconnect LCD, temper sensors

5. disconnect DCHG- power cable

6. disconnect BAT- power cable

Protection concept

OV/UV Protection

There are two OV/UV thresholds:

"CHG Limit" and "Over VOL"

"DCHG Limit" and "Under VOL"

The concept of using these parameters is as follows:

If the voltage of any cell reaches the thresholds "CHG Limit" or "DCHG Limit", the CHG FET or e-lock/throttle respectively will go off - the BMS will stay in normal state and will not issue an alarm.

If the voltage of any cell reaches the thresholds "Over_VOL" or "Under_VOL", the CHG FET or e=lock/throttle respectively will go off - the BMS will change to emergency state and will issue an OV/UV alarm as long as the limit violation persists.

Figure 2 OV/UV State machine

Table 2 Description of states (see Figure 2)

State	Description
normal voltage	No OV, UV event; Permit charge, discharge if no other protection events
high voltage	Prohibit charging; Permit discharge if no other protection events; if discharge current exists, that is discharge current < discharge state threshold, turn on CHG FET
low voltage	Prohibit discharge, When pre-charge function is enabled, if V_cell < UV threshold, permit pre-charge but prohibit charge; if V_cell ≥ UV threshold, permit pre charge and charge if no other protection events; When pre-charge function is not enabled, prohibit precharge but permit charge if no other protection events; If charge current exists, that is charge current > charge state threshold, turn on discharge MOSFET
over voltage	same as high voltage; issue alarm
under voltage	same as low voltage; issue alarm

Table 3 Description of states (see Figure 2)

Transition	Initial State	Final State	Condition
1	normal voltage	high voltage	HV event occurs (V_cell ≥ HV threshold & delay timer expires)
2	high voltage	normal voltage	HV event clears (V_cell < HV release value & delay timer expires)
3	normal voltage	low voltage	LV event occurs (V_cell ≤ LV threshold & delay timer expires)
4	low voltage	normal voltage	UV event clears (V_cell > LV release value & delay timer expires)
5	high voltage	over voltage	OV event occurs (V_cell ≥ OV threshold & delay timer expires)
6	over voltage	high voltage	OV event clears (V_cell < OV release value & delay timer expires)
7	low voltage	under voltage	UV event occurs (V_cell ≤ UV threshold & delay timer expires)
8	under voltage	low voltage	UV event clears (V_cell > UV release value & delay timer expires)

There are two situations that BMS "think" the battery is fully charged one of the cell reaches CHG Limit

but charging in CV state,charging current will be lower and lower, when charging current reaches CHG current

OC Protection

The concept of using 'Max_Continue_I', 'Pulse_Current Permit Time' and 'DCHG_OC' is explained in the following example:

settings: Max_Continue_I = 150A; Pulse_I Delay = 10s; DCHG_OC = 300; CHG_OC=30

If I_bat (discharging)<150A,e-lock/throttle is on

If 150A ≤ I_bat (discharging)< 300A, e-lock/throttle will go off after a delay of 10s; State shows 'OC'

If I_bat (discharging) ≥ 300A,e-lock/throttle will go off immediately (<10us); state shows'OC' or short

If I_bat (discharging) ≥ 30A,CHG FET will be off immediately

LCD

1st page：SOC,real-time current,total voltage,temperature,alarm info（OV,OC,OT,UV）

2nd page：voltage of highest and lowest,4 channels temperatures,state of battery

3rd page：1-16 cells voltage

4th page: capacity of pack,SOC,SOH

Name	description	limits [unit]	remarks
Cell 1-24	display the real time cell voltages as well as OV/UV status and balancing status	+5.399 [V]	the dots to the right turn red when bleeding of this cell is on. Bleeding starts with a delay of approx. 5min
Total Voltage	displays actual battery pack voltage	+130.0 [V]
Current	displays actual battery pack current	+300.0[A]
Pack Temp	displays actual battery pack temperature	+125.0 [°C] -30.0 [°C]	external temp sensor
Sys Temp	displays actual battery pack temperature	+125.0 [°C] -30.0 [°C]	internal temp sensor
CHG Enable	indicates charging mode	true / false
DCHG Enable	indicates discharging mode	true / false
Life cycle	displays the number of charge/discharge cycles	000
SOC	displays the State of Charge of the battery pack
State	displays the system's state	Discharging/Charging/ (Standby/OV/OC/OT/UV/Short/)

Parameter Settings

Name	description	range [unit]	action if threshold is exceeded
CHG Limit	sets the maximum cell voltage	0<V≤5'000 [mV]	switches off CHG-FET
CHG_Recover	sets the reset voltage of the 'CHG Limit' state	0<V≤5'000 [mV]	switches on CHG-FET when the 'highest' cell returns to the CHG_Recover threshold
CHG_Stop_Cur	sets minimum charge current	0<I≤5'000 [mA]	switches off CHG-FET after xx seconds
DCHG Limit	sets the minimum cell voltage	0<V≤5'000 [mV]	switches off throttle & e-lock
DCHG_Recover	sets the reset voltage of the 'DCHG Limit' state	0<V≤5'000 [mV]	switches on throttle & e-lock
Max_Continue_I	sets the max discharge current	0<I≤200'000 [mA]
Pulse_I_Delay	max. duration of pulse current	1<t≤30 [s]
DCHG_OC	sets the pulse current		switches off CHG- and throttle & e -lock and triggers OC alarm
CHG_OC	sets the max charging current		switches off CHG- and throttle & e-lock and triggers OC alarm
Difference_On	sets the max cell voltage difference ('highest' against the 'lowest' cell) at which bleeding begins	0<V≤2000 [mV]	bleeding of high cell(s) begins
Difference_Off	sets the min cell voltage difference at which bleeding stops	0<V≤2000 [mV]	bleeding of high cell(s) stops
Active_On	sets the min cell voltage to start bleeding	0<V≤5'000 [mV]	bleeding is enabled
Stop Balance Temp	sets the max Temperature of internal temp sensor	0<T≤70 [°C]	stops bleeding
Over_VOL	sets the maximum cell voltage	0<V≤5'000 [mV]	switches off CHG-FET and triggers OV alarm
Under_VOL	sets the minimum cell voltage	0<V≤5'000 [mV]	switches off throttle & e-lock and triggers UV alarm
OC Limit	sets the over current (peak current)	0<I≤300 [A]
OT Limit	sets the max Temperature of external temp sensor	-20<T≤80 [°C]	switches off CHG- and throttle & e-lock and triggers OT alarm
OT_Recover	sets the reset Temperature of the OT alarm state	50<T≤70 [°C]	switches on CHG- and throttle & e-lock
UT Limit	sets the min Temperature of external temp sensor	-20<T≤80 [°C]	switches off CHG- and throttle & e-lock and triggers UT alarm
UT_Recover	sets the reset Temperature of the UT alarm state	50<T≤70 [°C]	switches on CHG- and throttle & e-lock
Design Capacity	sets the nominal capacity of the battery pack	0<mAh≤500'000 [mAh]	enter manufacturer value
Current Capacity	sets the estimated initial capacity of the battery pack	0<Ah≤500'000 [mAh]	is dynamically adjusted according to real SOC. enter only once!!
SOC<	sets the min SOC	0<SOC<100 [%]	activates the BMS throttle limiting signal and issues a low power alarm

Capacity Setting

Capacity Setting is divided into two values, the 'Design Capacity', which is set to the nominal capacity of the battery pack and the 'Current Capacity', which is set to an estimated value of the battery pack's initial charge before connecting for the first time. After a number of charge and discharge cycles, the BMS will 'learn' the real SOC and will adjust these values automatically. You must not set these two parameters after the initial setup.

Cell Balancing

The concept of using "Difference_On" and "Difference_Off" is explained in the following example:

settings: Difference_On = 50mV ; Difference_Off = 30mV ; Active_On = 3'000mV

behaviour: if any number of cell voltages are at least 50mV higher than the lowest cell (i.e. Difference_On) and this lowest cell's voltage is higher than 3'000mV (i.e. Active_On), the BMS starts bleeding all 'high' cells (i.e. those above this 50mV threshold).

When all 'high' cells have reached a voltage 30mV above the lowest cell (i.e. Difference_Off) bleeding will stop

Tools

Name

description

range [unit]

remarks

First Chip

sets the number of cells connected

to the BMS via the first JST connector

4-12

Second Chip

sets the number of cells connected

to the BMS via the second JST connector

0 (if not used) or 4-12

BEEP ENABLE

Sets beep on/off

Current Adj

sets the calibration factor for

the current sensor

factory set!

'config2' shows

the hall sensor

voltage in [mV]

see 1)

Center Voltage

sets the offset for the current sensor

factory set!

Speed setting

Function not enabled yet!

Milage

Function not enabled yet!

Follow these steps to calibrate the current sensor (CS):

1. Run a cable connected to a constant current source in the range of 20A to 50A through the CS. A battery charger could supply the current. If the current is too low e.g. only 2A, you can wind the cable 10 times through the CS to reach 10x2A= 20A. Make sure the current flow direction is correct i.e. the arrow on the CS indicates the discharge direction from the battery.

2. switch off the constant current and confirm the BMS is in 'standby' state i.e. neither charging nor discharging.

3. copy the value displayed in 'config2' (approx. 2470-2500mV) to the 'Center Voltage' field and click 'Step1'.

4. Switch on the constant current and measure it with an amp meter.

5. copy the amp meter reading in [A] to 'Current Adjust' field and click 'Step2' to complete the calibration.

Possible configurations for cell numbers assigned to chip1 and 2

cells

chip1:chip2

comments

24s

12:12

23s

12:11

22s

12:10

11:11

21s

12:09

11:10

20s

12:08

11:09

10:10

19s

12:07

11:08

10:09

18s

12:06

11:07

10:08

09:09

17s

12:05

11:06

10:07

09:08

16s

12:04

11:05

10:06

09:07

08:08

15s

12:03

11:04

10:05

09:06

08:07

Electrical connections BMS pins and battery cells

Cells are stacked in the Pack and numbered from low to high i.e. Cell 1 is always the first cell which negative end is at the same time the negative end (minus pole) of the pack. In a 20s pack Cell 20 is the last cell and its positive end is the positive and of the pack (plus pole).

Each cell's negative and positive end is connected to the BMS via a single balancer cable which is used to measure the voltage and to draw some discharge current from each cell. Since all cells are stacked only one cable is required for any cell's positive end and the negative end of the successive cell.

The voltages in the pack are designated Vn_neg (negative end of Cell n, for short Vn-) and Vn_pos (positive end of Cell n, for short Vn+), there for Vn_pos = V(n+1)_neg e-bike BMS

comments: nc = not connected; red text = pay attention

For 13s and 14s battery packs continue the same scheme as indicated in the table above

For 4s to 12s battery packs use only first chip following the same scheme as indicated in the table above

Edit by editor

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Name	description	range [unit]	remarks
First Chip	sets the number of cells connected to the BMS via the first JST connector	4-12
Second Chip	sets the number of cells connected to the BMS via the second JST connector	0 (if not used) or 4-12
BEEP ENABLE	Sets beep on/off
Current Adj	sets the calibration factor for the current sensor		factory set! 'config2' shows the hall sensor voltage in [mV] see 1)
Center Voltage	sets the offset for the current sensor		factory set!
Speed setting	Function not enabled yet!
Milage	Function not enabled yet!

cells	chip1:chip2	comments
24s	12:12
23s	12:11
22s	12:10
22s	11:11
21s	12:09
21s	11:10
20s	12:08
	11:09
	10:10
19s	12:07
	11:08
	10:09
18s	12:06
	11:07
	10:08
	09:09
17s	12:05
	11:06
	10:07
	09:08
16s	12:04
	11:05
	10:06
	09:07
	08:08
15s	12:03
	11:04
	10:05
	09:06
	08:07

Product Overview We are upgrading the BMS,new version available now :-)