1. business and industrial
2. energy
3. electricity

Gateway to a New Thinking in Energy
Management - Ultracapacitors
By:
Maxwell Technologies - San Diego
January 18th, 2005
Ultracapacitors z Microelectronics z High-Voltage Capacitors
About Maxwell
Capacitor Manufacturer since 1965
www.maxwell.com
Maxwell is a leading developer
and manufacturer of innovative,
cost-effective energy storage
and power delivery solutions.
Certifications:
ISO 9001:2000
ISO/TS 16949
ISO 9002
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Manufacturing facilities:
US, Europe, Asia
Table of Content
1.
2.
3.
4.
5.
6.
7.
8.
When can I use an Ultracapacitor?
What is an Ultracapacitor?
Ultracapacitor Market
Ultracapacitor Applications
Sizing your System
Sizing Examples
Guidelines to Designing an Ultracapacitor System
Summary
Ultracapacitors z Microelectronics z High-Voltage Capacitors
When can I use an Ultracapacitor?
• Applications that require high reliability back-up power
solutions
• Short term bridge power 1 - 60 seconds for transfer to
secondary source or orderly shut down
• Power quality ride-through to compensate for
momentary severe voltage sags
• Power buffer for large momentary in-rush or power
surges
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Power vs Energy
What is the difference between Power and Energy?
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Application Model
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Peak Power Shaving
Peak Power Shaving
• Ultracapacitors provide peak power ...
Available
Power
Required Power
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Peak Power
Back-up Power
Back-Up Power Support
• Ultracapacitors provide peak power…
...and back-up power.
Available Power
Required Power
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Backup Power
What is an Ultracapacitor?
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Performance Characteristics
• Ultracapacitors perform mid-way between
conventional capacitors and electrochemical cells
(batteries).
• Fast Charge and Fast Discharge Capability
• Highly reversible process, 100,000’s of cycles
• Lower energy than a battery
~10% of battery energy
• Greater energy than electrolytic capacitors
• Excellent low temperature performance
Ultracapacitors z Microelectronics z High-Voltage Capacitors
What is an Ultracapacitor?
Ultracapacitors are:
ƒ A 100-year-old technology, enhanced by modern materials
ƒ Based on polarization of an electrolyte, high surface area electrodes and
extremely small charge separation
ƒ Known as Electrochemical Double Layer Capacitors and Supercapacitors
Dielectric
C = εr A/d
Minimize (d)
Maximize (A)
Electrolyte
E = 1/2 CV2
Film foil
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Electrode
ECDL
Separator
Technology Comparison
Available
Performance
Charge Time
Discharge Time
Energy (Wh/kg)
Cycle Life
Specific Power (W/kg)
Charge/discharge
efficiency
Lead Acid
Conventional
Ultracapacitor
Battery
Capacitor
1 to 5 hrs
0.3 to 30 s
10
-3
0.3 to 3 hrs
10 to 100
1,000
<1000
0.7 to 0.85
0.3 to 30 s
1 to 10
>500,000
<10,000
0.85 to 0.98
10
-3
Ultracapacitors z Microelectronics z High-Voltage Capacitors
to 10
-6
-6
s
to 10 s
< 0.1
>500,000
<100,000
>0.95
Technology Comparison (page 2)
1000
Fuel
Cells
10h
100
Energy Density/[Wh/kg]
0,1h
1h
36sec
LiBattery
Lead Acid
Battery
10
Ni/Cd
3,6sec
U/C
Double-Layer Capacitors
1
36msec
0,1
Al-Elco
0,36sec
0,01
10
100
1000
Power Density/[W/kg]
Ultracapacitors z Microelectronics z High-Voltage Capacitors
10000
Ultracap vs Battery Technologies
Efficiency
4
Charge Acceptance
Self Discharge
Pb-AGM
3
Temperature Range
Availability
2
NiMH
Li Ion
1
Environment
Ultracaps
Cycle Stability
0
Recycling
Energy Density
Safety
Power Density
System Cost
Energy Cost
Power Cost
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Market
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Market
Ultracapacitor World Market
Consumer Products
Industrial
Transportation
Digital Camera
UPS
Hybrid Bus/Truck
PDA
Windmill
Engine starting
Toys
Stationary Fuel Cell
Light Hybrid
Memory back-up
Automation/Robotics
Local Power
Rail
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Available Products
• Aqueous Electrolyte: ESMA, Elit, Evan, Skeleton Technologies and Tavrima
• Advantages:
• High electrolytic conductivity
• No need for tight closure to isolate
• Low environmental impact
• Disadvantages:
• Low decomposition voltage (1.23V)
• Narrow operational range (freezing point of water)
• Organic Electrolyte: Maxwell Technologies, Panasonic, EPCOS, Ness Capacitors,
ASAHI GLASS
• Advantages:
• High decomposition voltage
• Wide operating voltage
• Disadvantages:
• Low electrolytic conductivity
• Need for tight closure to isolate from atmospheric moisture
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Applications
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Applications
Automotive
Traction
ƒ 14/42 V systems
ƒ HEV
ƒ Electrical Subsystems
ƒ Regen braking
ƒ Voltage stabilization
ƒ Diesel engine starting
Large Cells
Consumer Electronics
Industry
ƒ Power quality
ƒ Pitch systems
ƒ Actuators
ƒ AMR
ƒ PDAs
ƒ Digital cameras
ƒ 2-Way pagers
ƒ Scanners
ƒ Toys
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Small Cells
Today’s Markets
Electric Rail Pack
Braking Energy Recapture
Diesel engine starting
Wind power plant pitch
systems
Burst power
TRACTION
Ultracapacitors z Microelectronics z High-Voltage Capacitors
INDUSTRY
Small cell applications
Digital cameras, AMR,
Actuators, Memory boards
CONSUMER
Ultracapacitors z Microelectronics z High-Voltage Capacitors
SITRAS® SES - Solution
Energy storage system:
Stationnary or on the vehicle
Time t1
Vehicle 1 is braking
Energy storage system stores the
braking energy
Time t2
Vehicle 2 is acccelerating
Energy storage system delivers the energy
Application: Time shifted delivery of the stored braking energy for vehicle reacceleration
Solutions: Possible with either stationary or on-vehicle energy storage system
Advantage: Cost savings through reduced primary energy consumption
Ultracapacitors z Microelectronics z High-Voltage Capacitors
SITRAS® SES - Benefits
Saved energy
kWh/h
50
⇒
Reduction of
the power
need by 50
kW
⇒
Energy
saving of
340.000 kWh
per year and
per
installation
⇒
thermal limit
68 kWh/h
40
30
20
10
0
04.08.01
07.08.01
Ultracapacitors z Microelectronics z High-Voltage Capacitors
10.08.01
13.08.01
MITRAC of Bombardier Transport
MITRAC energy saver
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Diesel Engine Cranking by Stadler
Ultracap module for diesel engine vehicles
ƒ Robust construction with voltage balancing
ƒ Easy to scale up for additional cranking power
ƒ Easy to integrate in existing housing
ƒ Easy to use, maintenance free
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Wind Turbine Pitch Systems
ƒ Modern wind turbines
consist of threebladed variable
speed turbines
ƒ Independent
electro-mechanical
propulsion units
control and adjust
the rotor-blades
ƒ Latest technology
uses the wind not
only to produce
wind energy but
also for its own safety
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Pitch System Storage Systems
ƒ Each pitch systems is
equipped with an
ultracapacitor emergency
power supply
ƒ Ultracapacitors represent
an optimum emergency
power supply system due
to their
• Enhanced level of
safety
• High reliability
• Efficiency
• Scalability
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Switch box
including 2600F
ultracapacitors
75 V, 81 F
ultracapacitor module
4 modules are put in
series to power 300 V
pitch systems of 3-5
MW wind power plants
Fuel Cell Powered Fork Lift
•
•
Fork lift equipped with a
fuel cell
Cell system and an
ultracapacitor module
•
ƒ
ƒ
ƒ
Ultracapacitors z Microelectronics z High-Voltage Capacitors
BOOSTCAP
module:
48 BCAP0010
112 V, 55 F
40 kW peak power
Vehicle Applications of Ultra-capacitors
•
Distributed energy modules are located at the actuator level in the vehicle
control hierarchy in close proximity to the actuator power driver
(should be within 18”).
Vehicle System
Controller
Power & Communications (PDA)
Steering
electric assist
Brakes
Regen Brake Sys
Steering actuator
Belt or Crankshaft
Rack
ECU
Mtr
UC
UC
UC
ECU
Steering
Wheel
HCU
Mtr
ISG
Torque
Continuous,
Scheduled,
Selectable
Transmission
ECU
ETC, Fan,
Water Pump
ECU
Brake
Pedal
Other 42V
Loads
SOC, SOH,Vsys
Brake actuators
Engine
Distributed
Energy Storage
Modules
Energy Storage
System Mgm't
ISG Subsystem
Accel
Throttle Pedal
Body
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Gear Sel, L/U Clutch
Oil Pump
UC
High Voltage
Battery Primary
Storage
HVAC
UC
Electric air
cond. comp.
Fuel Cells with Ultracapacitors
Ultracapacitors are accepted as the normal energy storage
option for fuel cells
•
•
•
Every major automotive company in the world is testing fuel cells as an
alternative drive train power system.
All significant fuel cell companies are either using or experimenting with
ultracapacitors as an integral part of the system.
Several major automotive companies have declared fuel cells with
ultracapacitors as their baseline system architecture. Honda and Hyundai have
gone public, others we are working with have not.
“Utilizing ultracapacitors we have gained an edge
in energy efficiency and throttle responsiveness
over competitors that are pursuing the hybrid
battery–fuel cell model”
Honda Motor Company
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Sizing Your System
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Data sheet
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Data sheet
Ultracapacitors z Microelectronics z High-Voltage Capacitors
How to measure Ultracapacitors
• To measure UC you need:
• bi-directional power supply (supply/load) OR
• separate power supply and programmable load (constant current capable)
• voltage vs. time measurement and recording device (digital scope or other data
acquisition)
• Capacitance and Resistance:
Capacitance = (Id * td)/(Vw - Vf) = (Id * td)/Vd
ESR = (Vf - Vmin)/Id
Vw = initial working voltage Vmin = minimum voltage under load
Id = discharge current
Vf = voltage 5 seconds after removal of load.
td = time to discharge from initial voltage to minimum voltage
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Basic Equations
Definition of Capacitance:
Charge = current * time: Q = I*t
Solving for voltage:
Dynamic Voltage:
Stored Energy
At initial voltage Vo,
At final voltage Vf,
C = Q/V
C = I*t/V
V = I*t/C
dV/dt = I/C
E = ½ C*V2
(1)
(1a)
(2)
(3)
(4)
Eo = ½ C*Vo2
Ef = ½ C*Vf2
Delivered energy = Eo – Ef
Ultracapacitors z Microelectronics z High-Voltage Capacitors
∆E =½ C*(Vo2 – Vf2)
(5)
Voltage & Current vs. Time
C = 15 farad; Resr = 100 milliohm
Vo = 48V; I = 30A
50
50
2–
dV/dt
==V
I/C
dV
I*dt/C
dV
∆E
=½
dV
I*dt/C
C*(V
==; Q/C
I*R
I*R
Vf2esr
)
total
esr
o =+esr
Voltage
45
40
Resr
i
40
Voltage (V)
45
-
35
+
30
+
C
-
35
25
Current (A)
Vo
20
30
15
Vmin
25
10
5
Current
20
0
-5
-4
-3
-2
-1
0
1
2
3
Ultracapacitors z Microelectronics z High-Voltage Capacitors
4
5
6
Time (sec)
7
8
9
10
11
12
13
14
15
Vf
Basic Model
• Series/Parallel configurations
• Changes capacitor size; profiles are the same
• Series configurations
• Capacitance decreases, Series Resistance increases
Rs=Rcell*(# of cells in series)
• Cs=Ccell/(#of cells in series)
• Parallel configurations
• Capacitance increases, Series Resistance decreases
RP=Rcell/(# cells in parallel)
• CP=Ccell*(# of cells in parallel)
• Current controlled
• Use output current profile to determine dV/dt
dV = I * (dt/C + ESR)
• Power controlled
• Several ways to look at this:
Pterm = I*Vcap –I2*ESR (solve quadratic for I)
I = [Vcap - sqrt(Vcap2-4*ESR*Pterm)]/(2*ESR)
• Solve for dV/dt as in current-controlled
• J=W*s=1/2CV2 Solve for C.
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Applications with a single
energy storage component
• Applications in which little total energy is
required (i.e. memory backup)
• Possibly used with other energy sources
• Short duration, high power (i.e. pulse transmit)
• Long duration, low power (i.e UPS backup)
• Opportunities for high charge rates (i.e toys)
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Applications with two
energy storage components
• Power vs. Energy design trade
when using two components
• Single component vs. two components
• Engines/Fuel cells/Batteries/Solar Arrays are energy rich/power poor
(or poor response)
• Size these components for enough energy, system may be limited in
power
• Size these components for power, system may have surplus of energy
• Ultracapacitors are power rich/energy poor
• Size an ultracapacitor for enough energy, system may have a surplus of
power
• Size an ultracapacitor for power, system may be limited in energy
• Two components
• A primary source for energy; Ultracapacitor for power
• Requires appropriate definition of peak power vs. continuous power
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Aging
• Unlike batteries, Ultracapacitors do not have a hard end
of life criteria.
• Ultracapacitors degradation is apparent by a gradual
loss of capacitance and a gradual increase in resistance.
• End of life is when the capacitance and resistance is out
of the application range and will differ depending on
the application.
• Therefore life prediction is easily done.
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Capacitance and ESR vs Frequency
ESR vs . Frequency
3,50E+03
7,00E-04
3,00E+03
6,00E-04
2,50E+03
5,00E-04
ESR [mOhm]
Capacitance [F]
Capacitance vs. Frequency
2,00E+03
1,50E+03
4,00E-04
3,00E-04
1,00E+03
2,00E-04
5,00E+02
1,00E-04
0,00E+00
1,00E-02
1,00E-01
0,00E+00
1,00E-02 1,00E-01 1,00E+00 1,00E+01 1,00E+02 1,00E+03
1,00E+00 1,00E+01 1,00E+02 1,00E+03
Frequency [Hz]
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Frequency [Hz]
C and ESR Temperature Dependency
1,2
2000
1,1
ESR [m O hm ]
0,9
1600
0,8
1400
0,7
0,6
1200
ESR BCAP0 0 0 8 (DC)
0,5
Cap acitance BCAP0 0 0 8
0,4
1000
-60
-40
-20
0
20
40
Temperature [°C]
Ultracapacitors z Microelectronics z High-Voltage Capacitors
60
80
100
Capacitance [F]
1800
1
BCAP Self Discharge
Self Discharge vs Temperature
100,0
90,0
% U (t = 0)
80,0
70,0
60,0
- 35 °C
50,0
+ 5 °C
+ 25 °C
40,0
+ 65 °C
30,0
0
2
4
6
8
10
12
14
16
Time [days]
Ultracapacitors z Microelectronics z High-Voltage Capacitors
18
20
22
24
26
28
30
BCAP Cycling Capacity
Change in Capacitance
[%]
110.0
2.0E-03
1.8E-03
1.6E-03
1.4E-03
100.0
90.0
Capacitance
80.0
70.0
ESR
60.0
50.0
0
20000
40000
60000
Cycle Number
Ultracapacitors z Microelectronics z High-Voltage Capacitors
80000
1.2E-03
1.0E-03
8.0E-04
6.0E-04
4.0E-04
2.0E-04
0.0E+00
100000
ESR [Ohm]
90 A CC, 1.15-2.3 V, 25 s, RT
BCAP Cycling
500’000 cycles between 1.8 and 2.7 V, 100 A
ESR (1 Hz) increase 140 % (0.49 to 0.79 mOhm
Capacitance decrease 38 % (2760 to 1780 F), 30% compared to rated capacitance
Ultracapacitors z Microelectronics z High-Voltage Capacitors
BCAP DC Life
Capacitance and ESR variation at U, T = 40 °C
105,0
200,0
100,0
180,0
95,0
160,0
90,0
140,0
120,0
% ESR (t = 0)
85,0
% C (t = 0)
2.5V 40°C
2.1V 40°C
2.3V 40°C
80,0
75,0
70,0
100,0
80,0
60,0
40,0
65,0
20,0
2.5V 40°C
60,0
0,0
2.1V 40°C
55,0
-20,0
2.3V 40°C
50,0
-40,0
0,0
100,0
200,0
300,0
duration [days]
Ultracapacitors z Microelectronics z High-Voltage Capacitors
400,0
0,0
100,0
200,0
300,0
duration [days]
400,0
BCAP DC Life
Capacitance and ESR variation at U, T = 65 °C
120,0
120,0
2.5V 65°C
2.1V 65°C
2.3V 65°C
100,0
100,0
80,0
% ESR (t = 0)
% C (t = 0)
80,0
60,0
40,0
40,0
20,0
0,0
2.1V 65°C
2.3V 65°C
2.5V 65°C
20,0
60,0
-20,0
0,0
-40,0
0
100
200
duration [days]
Ultracapacitors z Microelectronics z High-Voltage Capacitors
300
400
0
100
200
300
duration [days]
400
Sizing Examples
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Example sizing
1) Define System Requirements
15 W delivered for 10 seconds
10V max; 5V min
2) Determine total energy needed:
a) Determine Capacitance based on:
b) Substitute the energy from above:
c) Solve for C:
J=WS=10W*10sec=150J
J=1/2CV2
150J=1/2C(Vmax2-Vmin2)
C=300/(102-52)=4F
Csystem = 4.8F
3) Add 20-40% safety margin to cover I2R losses
4) Calculate number of cells in series (since maximum cell voltage = 2.5V)
10V/2.5V =
4 cells in series
5) Calculate cell-level capacitance
C = Csys * # of series cells = 4.8F* 4 =
19.2F per 2.5V “cell”
6) Calculate number of cells in parallel (we will assume a 10F cell)
# in parallel = 19.2/10F =
2 x 10F cells in parallel
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Guidelines to Designing an
Ultracapacitor System
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Cell Balancing
Why Cell Balancing?
• Achieve cell to cell voltage balance
• Accounts for variations in capacitance and leakage current,
initial charge and voltage dependent on capacitance, sustained
voltage dependent on leakage current
• Reduces voltage stress on an individual cell
• Increase overall reliability of the individual cells
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Cell Balancing
How to Cell Balance?
• Resistor method, resistor placed in parallel, resistor value
calculated at 10x leakage current for slow balance, 100x for
faster balance, good for low cycle when efficiency or stand
by loss not an issue
Surface Mount
Resistor for low
duty cycle
application
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Cell Balancing
• Active method, use semiconductors to limit or balance voltage
between cells, best for high duty cycle or when efficiency and
stand by loss from leakage current are important, highest cell
reliability option
Active cell to cell
balance circuit
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Cell Balancing
• Low Cost
• Scalable balance current
• 10mA, 300mA circuits
• Very low quiescent current (<20µA)
• No on/off required
• Modular installation
• N cells requires N-1 circuits
• Voltage independent
2600F cells; 4 in Series
Note high and
low points;
low
capacitance cell
Low capacitance,
high leakage cell
1.5 hours of Vehicle cycling (~ 200A)
300mA balancer for 50 & 60mm Ø cells
10mA balancer for 5F & 10F cells
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Cell Balancing
C1 Positiv e
R1
1M 1%
VPP
+
-
C1
R3
C1-C2 Midpoint
475 1%
Ultracapacitors
U1
VNN
R2
1M 1%
POS
C2
R4
499k 1%
C2 Negativ e
NEG
10mA Balancer
C1 Positive
100
R1
100K 1%
Q1
TLV2211CDBV
VPP
+
-
R2
100K 1%
POS
MMBT2222AWT1
C1
R3
5.6 1% 1.5W
C1-C2 Midpoint
Ultracapacitors
U1
VNN
100
R4
R6
C2
Q2 MMBT2907AWT1
C2 Negative
R5
49.9k 1%
300mA Balancer
Ultracapacitors z Microelectronics z High-Voltage Capacitors
NEG
Cell Balancing
Three cells with one cell balancing resistor removed:
OCTA Cycles Max. Voltage Profiles
5.00
4.50
4.00
Cell voltage (V)
3.50
3.00
C1-V
2.50
C2-V
C3-V
2.00
1.50
1.00
0.50
0.00
0
1
2
3
4
5
Day #
Ultracapacitors z Microelectronics z High-Voltage Capacitors
6
7
8
9
10
Ultracapacitor Packaging
Why Packaging?
•
•
•
•
•
•
•
Ensure proper mechanical stress
Ensure robust low resistance interconnect
Ensure proper electrical isolation
Ensure proper thermal considerations
Ensure agency compliance
Increase overall cell reliability
Reduce or eliminate maintenance requirements
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Packaging
How to Package Cells?
• Care should be taken for the electrical interconnect, a few key
guidelines to follow:
• Do not over torque. Over torque at the terminals may cause
internal failure of contact points. For example, the Maxwell
BCAP specification is 100 in.-lbs
• Use similar conductor metal interconnect bus bars to
eliminate galvanic corrosion.
• Good surface to surface contact will reduce inter-cell
resistance, reducing voltage drop and temperature stress
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Packaging
How to Package Cells?
• Cell to cell spacing should take into consideration two key
points and can be accomplished by the design of the
interconnect or the cell balancer:
• Depending on the cell some part of the outer case may be
electrically the same as one of the terminals, ensure electrical
isolation and watch for rubbing components that may wear
through ultracapacitor insulation, do not remove the factory
installed insulator sleeve
• Some air space between the cells allows convection cooling via
air flow improving reliability, depends on cycle time, short
duration high cycle applications may require forced air or other
cooling method
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Ultracapacitor Packaging
Electrical
Isolation
Aluminum
Interconnect
Proper Torque
and Hardware
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Summary
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Benefits Summary
Calendar Life
• Function of average voltage and temperature
Cycle Life
• Function of average voltage and temperature
Charge acceptance
• Charge as fast as discharge, limited only by heating
Temperature
• High temp; no thermal runaway
• Low temp; -40°C
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Benefits Summary
No fixed Voc
• Control Flexibility; context-dependent voltage is permitted
• Power Source voltage compatibility
• Examples; Fuel cells, Photovoltaics
No Vmin
• Cell can be discharge to 0V.
• Control Safety; No over-discharge
• Service Safety
Cell voltage management
• Only required to prevent individual cell over-voltage
State of Charge & State of Health
• State of Charge equals Voc
• Dynamic measurements for C and ESR = State of Health
• No historical data required
Ultracapacitors z Microelectronics z High-Voltage Capacitors
Useful Links
• Useful links on Maxwell Technologies Web-site:
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White Papers
Technology Overview
Sizing worksheet
Application Notes
Data Sheets
www.maxwell.com
Ultracapacitors z Microelectronics z High-Voltage Capacitors