Renault Megane Battery: Specs, Fitment & Common Faults

On the Megane, a genuinely surprising real root cause: a faulty immobiliser control unit caused a drain that stumped two dealers for three weeks.

Illustration for editorial purposes

OEM Part Number: 540-640A

Genuinely useful, sourced from the Megane II Owners' Club: Type 027 covers most petrol engines (62-64Ah depending on grade), while the 1.9 dCi diesel specifically needs the larger Type 096 — confirm your exact engine before ordering, since fitting the smaller 027 case to a diesel that needs 096 isn't a straightforward swap.

Most petrol engines (Megane II), Type 027	62-64Ah, 540-640A (EN) depending on grade — 242mm case
1.9 dCi diesel, Type 096	278mm case — genuinely larger than the petrol fitment
Megane III/IV, standard fitment	207-278mm length depending on engine, 175mm width, 175-190mm height

A Genuinely Surprising, Real Root Cause Worth Knowing About

If you've had two dealers and an auto-electrician all fail to find a persistent battery drain, this is genuinely worth knowing: one documented case, after three weeks of unsuccessful diagnosis, was eventually traced to a faulty immobiliser control unit itself — replacing it resolved the drain completely, with no reoccurrence six months later. This is a genuinely surprising root cause, and it's worth mentioning specifically as a possibility if you've already exhausted the usual suspects (interior lights, glovebox, boot light) without success.

A genuinely simple, free trick worth trying: some owners report a persistent drain stopping entirely after specifically deadlocking the car — pressing the lock button twice on the key fob, rather than just once — with no clear technical explanation for why, but consistent enough across reports to be worth trying before anything else.

It's also worth checking the glovebox door itself, not just the bulb: the plastic door can genuinely warp slightly over time, meaning the side that operates the internal switch retreats away from the switch plunger, leaving the light triggered even when the glovebox looks closed. If you've already removed the bulb and the drain persists, checking the door's fit and alignment against the switch is worth doing.

The Part Everyone Blames First, Not Always Correctly

A car that won't start gets blamed on the battery more often than any other component, and it's right often enough to make that assumption a reasonable first check. But it's not always the actual cause, which is worth knowing before spending money on a replacement that doesn't fix anything.

Before you buy: battery size, capacity and type (standard vs AGM/EFB for stop-start systems) vary by trim and engine. Always confirm against your VIN before ordering.

What It Does

The 12V battery provides the power needed to start the engine and runs electrical systems when the engine isn't turning. On cars with stop-start technology, the battery works much harder than on older designs, since the engine switches off and restarts far more frequently — which is exactly why these cars need a specific AGM or EFB battery type rather than a standard unit.

Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Battery Guide for warning signs to watch for, confirming fitment against your VIN, and matching the right technology (standard, EFB, AGM) when buying aftermarket.

More Renault Battery

The same part, covered across other Renault models.