Battery holder

A battery box protects the starter batteries and ensures safe, vibration-resistant mounting on MAN and Mercedes trucks, buses and vans. This includes not only the battery tray itself but, depending on the version, also mounting brackets, retaining straps, latches, drainage openings, insulation panels and holders for cables or main fuses. For vehicles in intensive use, an intact battery box is essential: loose batteries can damage battery terminals, battery cables, earth connections and the battery housing. Always select a battery box based on the chassis number. Visual comparison or selection based on the model name alone is never sufficient, as dimensions, mounting points, positioning and battery configurations differ by chassis version.

Battery boxes vary considerably between MAN TGL, TGM, TGS, TGX and TG3 models, older F2000, M2000 and L2000 series, as well as Mercedes Atego, Axor, Actros, Arocs, Antos and Econic. Battery holders may also differ between Sprinter, Vito, Viano, V-Class, Citan and TGE vans due to the engine bay layout, seat console, chassis variant or additional electrical equipment. For buses such as the MAN Lion’s City, Lion’s Coach, Mercedes Citaro and Tourismo, or Neoplan Cityliner and Tourliner, the battery arrangement is often integrated into an enclosed side compartment.

Before ordering, check the position of the battery box: on the chassis rail, behind the cab, in a side body compartment, under the cab floor or in the engine compartment. On trucks, batteries may also be fitted in a battery box mounted between the chassis rails at the end of the chassis. Also compare the external dimensions, base plate, centre-to-centre distance between mounting holes, diameter of the mounting bolts and height of the mounting brackets. A compartment for two 12 V batteries connected in series for a 24 V system has different dimensions and load points from a holder for one battery or a multiple-battery arrangement with auxiliary batteries.

On trucks, the battery isolator switch is often mounted on the battery box. This master switch interrupts the vehicle power supply and must correspond to the existing battery box and electrical system in terms of mounting position, connections and version.

The most common damage is caused by vibration, stone impact, moisture, road salt and insufficient battery clamping. Steel battery boxes can corrode at the base, weld seams and mounting lugs; plastic versions mainly crack around retaining strap guides, locking points and mounting bushes. A deformed base plate causes point loading on the battery housing, which may cause the battery to crack or electrolyte to leak. This accelerates corrosion of the battery holder, chassis rail and cable terminals.

Typical complaints include recurring starting problems, interruptions in the power supply, loose earth cables and control unit fault messages caused by voltage dips during starting. Therefore, check not only the battery capacity but also whether the batteries are mounted securely and stably. More than minimal play in the longitudinal or vertical direction indicates worn retaining straps, missing spacers or an incorrect battery size. Look for abrasion marks on the positive cables: damaged insulation near the metal edge of the compartment can cause a short circuit.

De-energise the battery box according to the vehicle procedure and disconnect the negative terminal first. Then inspect the base plate, the mounting points on the chassis and the condition of the retaining brackets. If in doubt, check the flatness of the base using a straightedge; local deformation must not exert pressure on the battery housing. Check drainage holes for blockages and remove acid or salt residues before fitting a new part.

Replace a battery box when corrosion affects the material thickness or load-bearing capacity, when mounting lugs are torn out, or when latches and retaining devices can no longer secure the batteries reliably. Repair by welding is only justified when the load-bearing structure, corrosion protection and original fit can be fully restored. For severely affected boxes, replacement is safer than local weld repairs.

Fit the new battery box using the correct fasteners and specified tightening torques. Install batteries with the correct base dimensions and polarity orientation, use suitable spacer blocks and tighten the retaining straps evenly without deforming the battery housings. After installation, check the earth connection by performing a voltage drop test during starting; an increased voltage drop indicates poor battery terminals, oxidised earth connections or insufficient contact with the chassis. Braem can assist with technical identification based on the chassis number and a suitable version from stock.