Mercedes-Benz - C-ClassMercedes C300 Battery Replacement in Dubai
The W204 C300 and the W205 C300 take different batteries in different case sizes, and neither will do the other's job properly. This page gives the group sizes for both, and we confirm yours from the VIN before a technician sets off.
Mercedes C300 at a Glance
- Battery type
- AGM
- Start-stop across the range.
- W204 group
- T6 / LB3 / 91
- Around 50Ah and 700 CCA.
- W205 group
- L3 / H6 / 48
- Around 70Ah and 760 CCA.
- W205 case size
- 278 x 175 x 190mm
- The standard L3 footprint.
- Auxiliary battery
- Passenger footwell
- On W205, behind trim under the glovebox.
- Coding
- Required
- Registered to the battery management system on fitting.
Mercedes C300 by Generation
The name stayed the same, the electrical system did not. Find the years your car was built in and the differences that matter.
BCI group T6, also listed as LB3 or 91. Roughly 50Ah and 700 cold cranking amps. A physically smaller battery than most people expect on a car this size.
BCI group L3, also listed as H6 or 48, at roughly 70Ah and 760 CCA in a 278 x 175 x 190mm case. Auxiliary battery relocated to the passenger footwell.
EQ Boost across the range, so a 12V AGM for conventional loads plus a separate 48V lithium battery for the integrated starter generator.
C300 Battery by Generation
Two generations, two group sizes, two case dimensions. This is the table worth having before you buy anything online.
| Specification | W204 (2007-2014) | W205 (2014-2021) |
|---|---|---|
| Group size | T6 / LB3 / 91 | L3 / H6 / 48 |
| Capacity | Around 50Ah | Around 70Ah |
| Cold cranking | Around 700 CCA | Around 760 CCA |
| Case size | Smaller T6 footprint | 278 x 175 x 190mm |
| Technology | AGM | AGM |
| Auxiliary battery | Separate AGM unit | Passenger footwell, under glovebox trim |
| Coding needed | Yes | Yes |
Figures from supplier fitment data. We check your VIN before fitting, because trim and build date can move these.
Why the Group Size Matters More Than the Badge
Group size is not marketing shorthand. It describes the physical case, the terminal positions and the hold-down arrangement, and getting it wrong has consequences beyond the battery not fitting neatly.
A battery that is loose in its tray moves. Vibration fractures the internal plates over time and causes micro-shorts between cells, which is one of the quieter ways batteries die early in cars that spend a lot of time on rough or fast roads.
Terminals matter too. Reversed polarity on a case that otherwise fits means cables stretched across the bay to reach, and a stretched cable is a hot cable. We fit the correct group for the generation rather than the nearest thing that drops in.
Checks Made on Every C300
Four things before a price is given, because on a car of this age more than one of them can be the real answer.
- Which GenerationW204, W205 or W206. It decides the group size, the case dimensions and on the newest cars whether there is a 48V system involved at all.
- Cranking Under LoadA resting voltage on a modern C-Class tells you very little. We measure what the battery can actually deliver.
- The Auxiliary UnitOn W205 it hides in the passenger footwell behind trim. It is a separate part with its own lifespan.
- Charging OutputAn alternator or regulator fault will destroy a new battery as efficiently as it destroyed the last one.
Signs a C300 Battery Is Going
The C-Class tends to give up conveniences before it gives up starting, so the first warnings are easy to ignore.
- Start-stop stops working, usually the earliest and most reliable indicator
- Slower cranking after a day standing in the sun
- An auxiliary battery malfunction message, pointing at the footwell unit rather than the main battery
- Media system or seat memory resetting after the car has stood overnight
- Warnings that appear on start-up and disappear once the engine is running
- The battery is past two years old and the car is parked outdoors
How a C300 Call-Out Unfolds
VIN and Generation
Confirmed on the phone so the correct group size leaves with the technician rather than being fetched afterwards.
Measured Before Quoting
Main battery under load, auxiliary unit, alternator output, and standing draw if the car has been flattening itself.
Correct Group Fitted
Correct group AGM installed, secured properly in the tray, and registered to the battery management system.
Signed Off on Site
Start-stop live, messages cleared, invoice and warranty issued, old battery removed for licensed recycling.
What Drivers of This Model Say
Bought a battery for my W204 based on a listing that said it fitted all C300s. It did not sit properly in the tray. …brought the correct T6 group, fitted it properly and explained why the other one would have shaken itself apart.
They quoted the exact group size on the phone before coming out, which nobody else did. Turned up with it, coded it, done in twenty five minutes at my building in Al Barsha.
Auxiliary battery warning had been on for months and two garages could not find the battery. It is under the glovebox. These guys knew immediately and sorted it same day.
Mercedes C300 Battery Questions
It depends on the generation. A W204 C300 takes BCI group T6, also listed as LB3 or 91, at around 50Ah and 700 CCA. A W205 takes group L3, listed as H6 or 48, at around 70Ah and 760 CCA in a 278 x 175 x 190mm case. We confirm yours from the VIN.
No. They are different case sizes with different hold-downs. A battery that does not sit properly in its tray vibrates, and vibration fractures the internal plates and shortens its life considerably. Fit the group the car was designed around.
In the front passenger footwell, behind a trim panel under the glovebox. Not in the boot and not in the engine bay, which is where most people look first. An auxiliary battery malfunction message refers to that unit rather than the main battery.
Yes. The W206 uses EQ Boost across the range, so there is a 12V AGM for conventional loads and a separate small 48V lithium battery driving the integrated starter generator. The two do different jobs and neither replaces the other.
Yes. The car sets its charging rate from what it believes about the battery's state, so without registration the alternator keeps running the profile it learned for the old one. We register it on the spot as part of the job.
Two to three years is typical, against the five you might see in a cooler climate. Every ten degrees above the 25C a battery is rated at roughly halves its life. We recommend a free test every six months once yours is past two years.
Not Your Model?
We fit batteries across the whole Mercedes-Benz range, and the marque page lists every model we cover.
Every Part of Dubai, Covered
Our vans work from points spread across the city, so the one nearest you is sent. Response is quickest around Business Bay and Downtown Dubai, and just as dependable out to Al Karama, Al Jaddaf and every home, office district and highway in between.
C300 Battery Due? Get the Group Size Right
Tell us the year or read us the VIN, and the correct group AGM comes to you, tested before we quote and coded before we leave. Anywhere in Dubai, 24 hours a day.
- Both batteries tested
- Coded to the car
- Old unit recycled