Simple Model of Lead-Acid Battery Model using LTspice

Lead-Acid Battery Simplified SPICE Behavioral Model

All Rights Reserved Copyright (C) Bee Technologies Corporation 2011 1

Contents

1. Benefit of the Model

2. Model Feature

3. Concept of the Model

4. Parameter Settings

5. Lead-Acid Battery Specification (Example)

5.1 Charge Time Characteristic

5.2 Discharge Time Characteristic

5.3 Vbat vs. SOC Characteristic

6. Extend the number of Cell (Example)

6.1 Charge Time Characteristic, NS=3

6.2 Discharge Time Characteristic, NS=3

Library Files and Symbol Files Location

Simulation Index


1. Benefit of the Model

• The model enables circuit designer to predict and optimize Lead-

Acid battery runtime and circuit performance.

• The model can be easily adjusted to your own Lead-Acid battery

specifications by editing a few parameters that are provided in the

datasheet.

• The model is optimized to reduce the convergence error and the

simulation time.


• This Lead-Acid Battery Simplified SPICE Behavioral Model is for users who

require the model of a Lead-Acid Battery as a part of their system.

• The model accounts for Battery Voltage(Vbat) vs. Battery Capacity Level

(SOC) Characteristic, so it can perform battery charge and discharge time at

various current rate conditions.

• As a simplified model, the effects of cycle number and temperature are

neglected.

2. Model Feature


3. Concept of the Model


Lead-Acid battery

Simplified SPICE Behavioral Model

[Spec: C, NS]

Adjustable SOC [ 0-1(100%) ]

+

-

• The model is characterized by parameters: C which represent the battery

capacity and SOC which represent the battery initial capacity level.

• Open-circuit voltage (VOC) vs. SOC is included in the model as an analog

behavioral model (ABM).

• NS (Number of Cells in series) is used when the Lead-acid cells are in series

to increase battery voltage level.

Output Characteristics

4. Parameter Settings

C is the amp-hour battery capacity [Ah]

– e.g. C = 1, 50, or 100 [Ah]

NS is the number of cells in series

– e.g. NS=1 for 1 cell battery, NS=2 for 2 cells battery (battery voltage is double from 1 cell)

SOC is the initial state of charge in percent

– e.g. SOC=0 for a empty battery (0%), SOC=1 for a full charged battery (100%)

TSCALE turns TSCALE seconds(in the real world) into a

second(in simulation)

– e.g. TSCALE=60 turns 60s or 1min (in the real world) into a second(in simulation), TSCALE=3600 turns 3600s or 1h into a second.

• From the Lead-Acid Battery specification, the model is characterized by setting

parameters C, NS, SOC and TSCALE.


Model Parameters:

(Default values)

5. Lead-Acid Battery Specification (Example)

• The battery information refer to a battery part number MSE Series of GS YUASA.


Battery capacity

[Typ.] is input as a

model parameter

Nominal Voltage 2.0 [Vdc] /Cell

Capacity 50Ah

Rated Charge 0.1C10A

Voltage Set 2.23 [Vdc] /Cell

Charging Time 24 [hours] @ 0.1C10A

5.1 Charge Time Characteristic


• Charging Time: 24 [hours] @ 0.1C10A

(hour)

Measurement Simulation

SOC=0 means

battery start from 0%

of capacity (empty)

Current: 5A (0.1C10A)

Voltage: 2.23V

5.1 Charge Time Characteristic Simulation Circuit and Setting

.TRAN 0 24 0 25m

.LIB lead-acid_battery.sub


Charge Voltage

A constant current charger at

rate of capacity (e.g. 150A)

1 hour into a second

(in simulation)

5.2 Discharge Time Characteristic


(hour)


SOC=1 means

battery start from

100% of capacity

0.1C10A

0.23C10A

0.65C10A

1.0C10A

5.2 Discharge Time Characteristic Simulation Circuit and Setting

.TRAN 0 10 0 25m

.STEP PARAM rate LIST 0.1, 0.23, 0.65, 1

.OPTIONS ABSTOL=1.0E-9



A constant current discharger at

rate of capacity (e.g. 150A)

TSCALE turns 1 hour into a second(in

simulation), battery starts from 100%

of capacity (fully charged)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 1 2 3

(% o

f R

ate

d C

apacity

)

Discharge Rate (Multiples of C)

Mesurement

Simulation

5.3 Vbat vs. SOC Characteristic


• Nominal Voltage: 2.0V

• Capacity: 50Ah

0.1C10A


Simulation

0.25C10A

0.6C10A

1.0C10A

[0-100%]

@25C

5.3 Vbat vs. SOC Characteristic Simulation Circuit and Setting


.TRAN 0 10 0 100m




A constant current

discharger at rate of

capacity (e.g. 150A) 1 hour into a second

(in simulation)

Voltage - Rated 6.0 [Vdc] /Cell

Capacity 100Ah

Rated Charge 0.1C10A

Voltage Set 2.23V*3 [Vdc] /Cell

Charging Time 24 [hours] @ 0.1C10A

6. Extend the number of Cell (Example)

• The battery information refer to a battery part number MSE-100-6

of GS YUASA.


The number of cells

in series is input as

a model parameter

Basic Specification

Lead-Acid needs

3 cells to reach

this voltage level

0.2

6

Acid-Lead

VoltageNominal

RatedVoltageNS


• Charging Current: 10A (0.1C10A)


(hour)

The battery needs 24 hours to be fully charged

Charge Current: 10A (0.1C10A)

Charge Voltage: 6.69V


Simulation Circuit and Setting

.TRAN 0 24 0 25m



Charge Voltage


(in simulation)

• Voltage - Rated: 6.0V

• Discharging Current: 10A(0.1C), 23A(0.23C), 65A(0.65C), 100A(1.0C)

6.2 Discharge Time Characteristic, NS=3


(hour)

0.1C10A

0.25C10A

0.6C10A

1.0C10A

6.2 Discharge Time Characteristic, NS=3 Simulation Circuit and Setting

.TRAN 0 10 0 25m





Parametric sweep “rate”

for multiple rate

discharge simulation


(in simulation)

Library Files and Symbol Files Location


…¥Simulation

C:¥Program Files¥LTC¥LTspiceIV¥lib¥sub

C:¥Program Files¥LTC¥LTspiceIV¥lib¥sym

Copy/

Paste

into

Copy/

Paste

into

1. Copy the library files (.lib) from the folder …¥Simulation¥.sub¥, then paste into the folder

C:¥Program Files¥LTC¥LTspiceIV¥lib¥sub

2. Copy the symbol files(.asy) from the folder …¥Simulation¥.asy¥, then paste into the folder

C:¥Program Files¥LTC¥LTspiceIV¥lib¥sym

Simulation Index


Simulations Folder name

1. Charge Time Characteristic.................................

2. Discharge Time Characteristic.............................

3. Vbat vs. SOC Characteristic..................................

4. Charge Time Characteristic, NS=3.......................

5. Discharge Time Characteristic, NS=3...................

Charge_Time

Discharge_Time

Discharge_SOC

Charge_Time(NS)

Discharge_Time(NS)

Technology

Simple Model of Lead-Acid Battery Model using LTspice