Electrics without guesswork — measure first, replace second
A modern Mercedes carries over 70 control units linked by CAN, LIN and FlexRay networks — and the biggest electrical bills come from mechanics who swap parts until a fault disappears. We work the other way round: measure, localise, then replace. At our workshop in Radiofar (Belgrade) we handle:
- Parasitic drain measurement per circuit — finding exactly which module draws current while the car sleeps
- AGM / EFB battery replacement with mandatory XENTRY registration and auxiliary battery check
- Alternator and starter diagnostics and repair, charging voltage measured under load
- Key coding and replacement, keyless-go system repair
- LED, ILS and MULTIBEAM headlight service — modules, calibration, coding after replacement
- CAN / LIN network diagnostics with an oscilloscope — breaks, shorts, modules dragging the bus down
Why a new battery must be registered
The Mercedes energy-management system adapts charging to the battery age and type. If a new battery is not registered via XENTRY, the system charges it as an old one: its life shortens by 30-50% and start-stop simply stops working. With us, every replacement includes registration, a quiescent-current check and an alternator test — all in the same visit, under an hour.
Battery drains overnight?
The usual suspects are modules that fail to sleep (COMAND, antenna amplifiers, bonnet/boot switches), a faulty Webasto or alternator diodes. We measure quiescent current fuse by fuse as the car falls into sleep mode and isolate the exact circuit — without tearing out half the harness or replacing healthy parts.
FAQ — electrics and batteries
My battery drains overnight — how do you find the cause?+
By measuring parasitic (quiescent) current per circuit while the car falls into sleep mode. That shows exactly which module or circuit draws current — most often multimedia, antenna amplifiers or the Webasto — and we repair only that.
Does a new battery really need to be registered?+
Yes. Without XENTRY registration the energy management charges the new battery as an old one: its life shortens by 30-50% and start-stop stops working. Registration is included in every replacement with us.
Start-stop stopped working — is that a fault?+
Usually not a fault but a weakened battery: the system disables start-stop as soon as it judges the battery cannot safely restart the engine. We test the battery state of health and charging — 20 minutes and you know where you stand.
I lost my key / the key does not work — can you help?+
Yes — we diagnose, repair and code keys and keyless-go systems. For a new key you need proof of ownership and the vehicle document.
How long does a Mercedes battery last?+
Typically 4-6 years, less with many short trips and cabin pre-heating/cooling while parked. We test AGM batteries free with every service — replacing before failure always beats a tow truck.