TECHNOLOGY

State of the art
The demands on power and energy in the vehicle electrical system continue to increase.
At the heart of the vehicle electrical system is the battery, which was already one of the most important branches of the battery industry in 2004 with 350 million starter batteries produced. In addition to the volumetric and gravimetric energy and power density, the (discharge) charging efficiency, the number of tolerable discharge cycles, safety and temperature resistance are also relevant in addition to the costs. As the batteries are disposed of after use, their environmental friendliness is also crucial.
In the case of the combustion engine, the energy requirement for starting the engine in particular is covered, but consumers also need to be supplied when the vehicle is stationary for longer periods, which means that two batteries are sometimes used. Purely electric vehicles, such as the Tesla Model X, also use a lead battery to supply the safety systems, the touchscreen and the high-voltage contactors.
With the exception of classic cars, commercially available motor vehicles have an on-board power supply voltage of 12V (in the commercial vehicle sector, sometimes also 24V).

The standard car battery is mounted in such a way that it cannot move (by means of a clamping frame, bracket or floor mounting). The battery is usually installed in the engine compartment, if space and ambient temperature allow, or in the boot or passenger compartment...

Under normal conditions, the applied load is between 50mA (quiescent current) and 70A (constant charging current) via the alternator while driving and short-term power peaks of approx. 300A for 3s to overcome the breakaway torque when starting the combustion engine.
The latter, in particular, dimensions the battery, whereby shorter cables to the consumer reduce the voltage drop and thus battery capacities can be reduced.
In the past, the lead starter battery has been optimised to such an extent that only limited technical improvements can be expected, although a cost advantage has been established.
Through Increased requirements due to complex energy management systems In modern vehicles, the classic automotive starter battery based on lead-acid (wet, gel, EFB, AGM) is subject to increased wear and tear, with a service life of three to five years.

Technology comparison
The figure compares the typical gravimetric energy and performance of lead-acid batteries with bound acid with lithium batteries. It can be seen that the lithium application offers advantages, particularly for the performance characteristics. The volume and mass in relation to the power could be quartered and the available energy increased. This is because lithium is the lightest solid element and has the lowest standard potential in the electrochemical voltage series:

Whereas in lead batteries, disordered chemical reactions build up or break down the electrode during conversion, the grid structure remains intact during intercalation in lithium batteries and only the lithium ions are stored or removed, so that longer lifetimes are achieved.
Lithium batteries are usually named after the material used for the positive electrode. The lithium iron phosphate battery, patented in 1996, is thermally stable (no thermal effects occur up to 300° C), non-toxic and offers advantages in the absorption and release of energy, although it has disadvantages in terms of cell voltage energy density. Furthermore, 𝐿𝑖𝐹𝑒𝑃𝑂𝑂4 offers a plateau-like progression of the voltage over the capacity, so that the available battery capacity can be utilised more effectively. In addition, 𝐿𝑖𝐹𝑒𝑃𝑂4 batteries do not burn, do not release oxygen and have a high cycle stability compared to other cell chemistries. This results in a 𝐿𝑖𝐹𝑒𝑃𝑂4 battery life expectancy of over 123,000 cycles compared to 72,000 or 21,000 cycles for a lead-acid battery with bound acid. Cold-start capability is also achieved with the current 𝐿𝑖𝐹𝑒𝑃𝑂4 cells.
With regard to CO2 emissions during production, the figure below shows a comparison of 𝐿𝑖𝐹𝑒𝑃𝑂𝑂4 with two lithium nickel cobalt aluminium oxides (NCA), lithium titanium spinel (LTO) and lithium nickel manganese cobalt oxide. It can be seen that 𝐿𝑖𝐹𝑒𝑃𝑂4 has the lowest (cradle-to-gate) average emission value of 252 𝑘𝑔 𝐶𝑂2𝑘𝑊ℎ during production:

The capacity of a battery depends, among other things, on the discharge current, the time course of the discharge and the age of the battery. The C-rate is used as a comparative value to quantify the discharge, which indicates how long the battery can be discharged with this current:

Battery management system (BMS)
The most important electronic component is the battery management system which, in addition to controlling and monitoring the state of charge, forms the interface to vehicle communication.
All of our units are equipped with a specially developed, technology-leading battery management system (BMS) with optional integration via the vehicle communication system (CAN / LIN bus).
In this context, the units in the field can be synchronised via an integrated Bluetooth interface. via your own smartphone app can be permanently monitored and, if necessary, proactively maintained remotely (Industry 4.0 standard).
In other words, in addition to the actual products, we also offer comprehensive support fulfilment in the field of "intelligent" car batteries:

Cell technology

The LiFePO4 or LFP rechargeable battery is a further development of the lithium-ion rechargeable battery in which the conventional lithium cobalt oxide cathode has been replaced by a lithium iron phosphate cathode.
It is characterised by high charging and discharging currents, very good temperature stability and a long service life.
Almost the entire stored energy can be extracted from LiFePO4 cells, compared to 30-35% for conventional lead-based starter batteries, depending on the quality.
Due to the degressive voltage characteristic during discharge, there is no longer enough energy available to start the vehicle very early on. In contrast, the voltage characteristic curve of the LiFePO4 cells remains almost constant throughout the entire discharge process based on the figure above, which enables reproducible power extraction.
With regard to the design of the cells, the cylindrical cell is the most common type of battery cell and also offers the advantage that it does not expand outwards when heated (in contrast to pouch or prismatic cells, which expand at a high state of charge).
For our development projects, we generally use pre-sorted premium 𝐿𝑖𝐹𝑒𝑃𝑂4 round cells type ANR26650M1B from the manufacturer LithiumWerkswhich are laser-welded using copper strips: