Forestry technology
MM Forsttechnik GmbH (Austria)
Background
MM Forsttechnik GmbH is an Austrian manufacturer of cable crane systems for forestry operations. Cable cranes are deployed on steep terrain to extract timber from hard-to-reach areas — the cable runs under load and the system operates continuously.
The electrification of the system was intended to integrate a lithium battery as the energy storage. From the outset it was clear that operating conditions in the forest would place special demands on the mechanical design, electronics and energy management.
The problem
Three factors made a standard battery unsuitable for this application. First, the mechanical load — continuous cable movement generates sustained oscillation, and attaching and pulling timber trunks produces hard shock loads. Plastic housings and unrestrained cell connectors do not withstand this sustained stress over time.
Second, regeneration: lowering loads and returning the empty cable generates recharge currents well above normal charging levels. A standard BMS not designed for these current spikes either shuts down prematurely or damages the cells. Third, control integration: the cable crane's machine controller runs on a PLC — the battery had to communicate compatibly with it.
Requirements
- ✓Steel enclosure: mechanical protection against impacts and shocks in forestry operation
- ✓Damped mounting: vibration isolation against sustained oscillation from the running cable
- ✓Regenerative BMS: safe handling of high regenerative recharge currents without shutdown
- ✓PLC-compatible interface: communication with the cable crane's machine controller
- ✓Continuous operation reliability: dependability under extreme environmental conditions
Solution
The enclosure was manufactured from steel — protecting cells and electronics from the mechanical stresses of forestry operation and robust enough to withstand hard shock loads. Inside the enclosure, the battery pack is mounted on vibration isolators: these decouple the cells from the sustained oscillations of the running cable.
The BMS was tuned to handle the high regenerative currents. It detects recharge impulses, processes them safely and protects the cells from overcharge even during unexpected load spikes. At the same time, the BMS provides a PLC-compatible communication interface through which the cable crane's machine controller reads state of charge, operating status and fault messages from the battery.
The complete system was built as a prototype and commissioned directly in the cable crane.
Outcome
The prototype was tested in demanding real-world forestry operation and has proved itself under actual operating conditions. Sustained vibration, shock loads and regenerative currents have not impaired the battery pack. The experience gained from the prototype deployment forms the basis for further development of the cable crane system.
Technical background
→ Batteries for forestry technology
Solution overview for forestry and special machinery
→ Regeneration in cable crane systems
How regenerative currents arise and how the BMS handles them
→ What a BMS actually does
Voltage window, balancing, SoC/SoH, CAN-bus connection
→ LiFePO4 vs. Li-NMC
Which cell chemistry suits which application