Power Pack Helps to Locate Mobile Objects
Tadiran Batteries offers the PulsesPlus battery – a new safe energy supply for long-term applications with high pulse currents. It is a new kind of battery system with high energy and power density, based on the well-tried 3.6 V lithium battery technology.
Pulse currents – the challenge
The interest in stand-alone, high energy batteries is growing continuously. They must have a long service life and they must be capable of supplying high current pulses. The application areas include GPS and GSM based locating and survey systems for mobile goods as well as data logging equipment via GSM.
In order to meet these extended market demands Tadiran Batteries offers the PulsesPlus series, a new battery system combining the excellent long-term properties of lithium primary batteries with the excellent pulse capability of a new kind of charge storing element, a Hybrid Layer Capacitor (HLC). It is based on the lithium-ion technology.
Primary lithium batteries of the so-called “bobbin“ design over the last two decades have proven to be the most suitable energy source for long-term applications like utility meters i. e. heat counters and heating cost allocating systems, like wireless alarms and others. However, due to its limited current capability, this technology meets its limits when higher current pulses are required. Examples are applications like radio automatic meter reading (AMR) or data transmission using GSM based data loggers.
Lithium batteries with spirally wound electrodes, although they are by design able to supply high currents, are not the best suited solution for such demanding applications both because their energy density is lower than that of bobbin type batteries and, moreover, the self-discharge rate is relatively high.
PulsesPlus – the solution
The PulsesPlus series overcomes these shortcomings of conventional solutions by combining Tadiran Batteries primary batteries with one or more Hybrid Layer Capacitors. The properties of both components are listed below.
Tadiran Batteries primary batteries have the following outstanding characteristics:
- high cell voltage: 3.6 V (optional 3.9 V)
- maximum energy density: e. g. D (Mono) size 19 Ah
- wide temperature range: -55 °C up to 130 °C (standard 85 °C)
- low self-discharge (< 1 % p. a.) / long storage capability
- high degree of inherent safety (no safety vent needed)
- hermetical sealing (glass-to-metal seal, laser welded can)
The main characteristics of the Hybrid Layer Capacitor are:
- outstanding high power capabilities (in the Ampere range)
- high cell voltage (up to 3.9 V)
- high degree of inherent safety
- low self-discharge, long storage capability
- no passivation problems, no voltage delay
- wide temperature range (-40 °C to 85 °C)
- hermetical sealing (glass-to-metal seal, laser welding)
Benefits from synergy
By combining the two components in a parallel connection, the HLC is capable of delivering high pulse currents at any time while it is being recharged from the primary battery. This concept offers outstanding advantages:
- stand-alone, maintenance free solution
- independent from external sources
- low weight
- high energy density
- high power density (pulse rate capability)
- long service life (up to 10 years)
- wide temperature range
- high degree of inherent safety
- high degree of reliability
The two figures below show the advantages of the PulsesPlus series compared to primary lithium batteries.
Figure 1 compares PulsesPlus to lithium/thionyl chloride (Li/SOCl2) cells in bobbin and spiral design. A basic current of 70 µA was taken from one C-size cell. Mathematically, this corresponds to a service life of approximately 10 years. Pulses of up to 160 mA were drawn at a pulse length of 5 s. Figure 1 shows the resulting available capacity as a function of the pulse amplitude.
If the pulse current for instance exceeds of 100 mA both designs have less than 3 Ah available capacity, while the PulsesPlus battery, comprising a 3.6 V lithium cell and an HLC-1520 has an available capacity of approximately 6 Ah over the entire range of pulse amplitudes.
Figure 2 compares PulsesPlus to batteries of the 3 volt systems, Li/MnO2 and Li/CFx. Available capacity is plotted over pulse amplitude. Again, the PulsesPlus technology proves its superiority.
Acquiring new market segments
Due to the addition of a relatively small component, the HLC, the available capacity in an application has been increased drastically (up to more than 100 %). In addition to the better technical solution, the customer also obtains a distinct economic advantage. The battery is smaller and lighter. The service life is longer. The expenses for battery replacement are lower.
Thanks to these outstanding properties the PulsesPlus battery has been successful in various applications in the area of locating and monitoring systems of mobile assets, like railway wagons and trailers. The electrical current profile in such long-term applications is typically composed of a low continuous current of a few microamperes in combination with high transmission pulses of up to a few amperes during some milliseconds or seconds.
Further typical applications for the PulsesPlus series are: telematics: emergency call systems, navigation; medical applications: mobile defibrillators; oceanographical units; safety systems: locking systems, wireless alarms; utility meters: equipment for remote meter reading.
Example: GPS/GSM locating system
GPS/GSM based railway wagon locating is one of the toughest applications for a battery system. It can be considered as an automatic mobile phone, equipped with a GPS locating system, capable of operating outside in all weather conditions, sending and receiving SMS messages without recharging the battery for 5 or 10 years.
GSM (Global System for Mobile Communications) is the most successful mobile communication system in the world. Datalogging and vehicle locating systems typically use the SMS feature offered by GSM. GPS (Global Positioning System) is currently the most widely used system allowing a receiver to determine its location. It evaluates the signals from a set of military satellites.
GSM modules in transmission mode typically require average currents of approximately 300 mA. During a time slot occupying 577 µs within a frame of 4.615 ms (8 slots), a data burst requires pulse currents of up to more than 2 A. Pulse width and frequency are standardized while the current amplitudes depend on the actual situation. Usually the amount of data is small and the system is in transmission mode for less than a second per day. The resulting power consumption per day is very low while it is very high during transmission.
Other contributions to the load profile include the RTC, the GPS receiver, the CPU, as well as optional sensors. Table 1 contains a typical GPS/GSM application and its optimized battery solution. A comparison with competing power supply systems is given in Table 2.
|Device||Trailer location system|
|RTC||0.1 mA continuous|
|Microcontroller||20 mA, 15 min per day|
|SMS receiver||7 mA, 15 min per day|
|GPS receiver||40 mA, 6 min per day|
|SMS transmitter||2000 mA, 200 bursts per day|
|Average current||0.55 mA|
|Minimum voltage||3.0 V|
|Temperature profile||-40 °C...+85 °C|
|Vibration and shock||According to railway and road conditions|
|Nominal voltage||3.6 V|
|Nominal capacity||76 Ah|
|Pulse current capability||2 A|
|Space requirement||65 x 70 x 70 mm³|
|Life expectancy||10 years|
Table 1: Trailer location, a typical GPS/GSM application and its battery solution
|Power Source||Alkaline||Lead acid with solar panel||PulsesPlus|
|Key: ++ very good + good 0 acceptable - poor -- insufficent|
Table 2: Comparison of different battery solutions for railway wagon and trailer locating systems.
The PulsesPlus series from Tadiran Batteries is the combination of the best features of both worlds: a primary lithium battery with high and stable voltage, high energy density, and long service life and an HLC, which is recharged by the primary battery and delivers the high pulse currents to the application. In combination, they comprise a long term stand-alone power source, capable of supplying high current pulses over a wide range of environmental conditions.
Today, Tadiran Batteries is the leading supplier of primary lithium batteries for industrial applications in Europe.
Professional application engineering is one of the strengths of Tadiran Batteries. It requires close co-operation with our customers in an early stage of the design-in phase. The company underlines its responsibility for market and environment by a management system certified for compliance with ISO 9001 (since 1991) and ISO 14001 (since 1999). Total Quality Management and a strong customer focus are vital elements to the company.
Tadiran Batteries GmbH
63654 Büdingen, GERMANY
Phone: +49 (0) 60 42 / 9 54 - 1 21
Fax: +49 (0) 60 42 / 9 54 - 1 90