At the rear end of the truck there is even enough space for two large batteries. However, the location at the rear end of the tractor unit also causes additional stress on the battery. The shocks and vibrations which act on the rear axle are also transferred to the battery.
In addition to the increased vibration and shocks due to the position above the drive axle, truck batteries are also subjected to stresses due to other mechanical factors. Location at the rear can amplify unwanted oscillations and resonances. With conventional battery designs the continuous vibration can considerably reduce the life of the truck battery. Thanks to special constructional features, batteries for end-of-frame installation are equipped to deal with the increased vibration requirements.
This can be identified from the "END OF FRAME INSTALLATION" symbol on the battery
In order for truck batteries to meet the requirements of modern long distance goods transport the European battery standard EN50342 has been revised. According to the test which is specified in directive V3, a truck battery must withstand a 20-hour vibration test in a spatial axis at a frequency of 30 Hz. Since the revision of the standard there is now a new requirement V4, which allows for the increased vibration requirements.
The new directive V4 achieves a better approximation to real-life operation. Truck batteries must withstand a five-hour vibration test in all three spatial axes over a frequency spectrum from 5 to 100 Hertz. Only a few batteries on the market withstand this severe test. These include the VARTA® Truck AGM battery and the VARTA® Truck EFB battery.