Lithionator TRAC offers traction battery systems for industrial trucks in standard tray dimensions according to DIN. Prismatic lithium-ion cells in iron phosphate (LiFePO4) technology are assembled in the trays. The available cell sizes are:
40, 60, 66, 100, 200, 300 and 400 Ah.
The serial connection of the cells to the desired nominal voltage is made in the following manner:
24 V battery systems with 8 cells à 3.2 V to 25.6 V rated voltage
48 V battery systems with 15 cells à 3.2 V to 48.0 V rated voltage
80 V battery systems with 25 cells à 3.2 V to 80.0 V rated voltage
Whether in the trays is still a parallel connection of cells required depends on the individual tray and the built-in capacity. For the capacity there are two contrary layout possibilities:
1. Full expansion towards capacity
Here the maximum possible capacity is installed in the tray, so the weight no longer corresponds to the mass of the equivalent lead-acid battery system. The battery system is thus considerably lighter (30 to 50%). This variant can be used only if the weight of the battery system is not necessarily a criterion for the operation of the vehicle as for example, in so-called counter balance trucks or tractors. For pure counter balance trucks this variant is ruled out. For reach trucks an individual assessment is needed. Means, it is necessary to consider which loads are moved and how far the weight of the battery system may decline in relation to the leverage.
The advantages of this version are:
- Time and cost savings due to longer run times of the device without battery system change
- Time and cost savings through to additional energy by intermediate charges
- Cost savings through 1.6 to 1.7 times as many cycles of use (2000 cycles lithium Battery system to 1200 cycles lead acid battery system)
2. Installation of a smaller capacity.
As the nominal capacity of the lithium battery system is one hour capacity (C1) and can be discharged with 100% (DOD), while the lead-acid battery systems nominal capacity is a five hour capacity (C5) and only 80% (DOD) can be discharged, one need only about 65% of rated capacity of a lead acid battery system in order to achieve the same run time for the truck. In this case, the free volume in the tray can be used to get the equivalent weight of lead-acid a battery system with additional steel.
- Time and cost savings through additional energy by intermediate charges
- Cost savings through 1.6 to 1.7 times as many cycles of use (2000 cycles to 1200 cycles lithium battery system lead acid battery system)
- Cost savings in comparison: 1.
Of course, optimization / compromises between 1. and 2. depending on the individual tray are possible.
All 8, 15 or 25 cells of the battery system have a so-called “balancer”, which in the beginning of operation compensates individual state of charge of the cells from cycle to cycle and sustain from cycle to cycle after reaching the equilibrium. The “balancer” used to work with semiconductors and not with power resistors, so that no unnecessary heat is generated by the “balancer”.
Battery Management System
The cells are monitored by the BMS (Battery Management System) via the “balancers” with respect to the voltage. Cell temperatures are measured at various points between the cells. Likewise, the BMS measures the charge and discharge current via a Hall sensor. The BMS switches the battery system to discharge and charge via a vacuum relay, this allows if a fault occurs a safe emergency separation even under full load. The BMS determines the current status of the battery system and monitors all cell parameters so that limit violations are detected and the battery system is disconnected, if necessary.
The cells, the BMS and its components are installed in the tray under a lid. The lid is fixed by tamper proof screws and provided with a seal. From the cover the charger cables are led out with strain relief.
Durable, Space-saving, and lightweight
Lithium-Ion accumulator systems are more durable, space-saving, and lighter than conventional systems with VLRA battery systems. They offer great advantages with regard to operational security as well as to economic viability.