Land Rover Discovery HSE Key Fob Replacement Battery 3V 50mAh

Land Rover Discovery HSE Sport Utility 4-Door — 3V Lithium Vanadium Pentoxide Replacement Battery

This 3V, 50mAh lithium vanadium pentoxide cell replaces the key fob battery in the Land Rover Discovery HSE, Discovery SE, Sport Supercharged Dynamic, and Sport Supercharged Sport Utility 4-Door, plus 14 additional variants. It powers the keyless entry remote, covering remote lock, unlock, and trunk release functions. Dimensions are 23.60 x 23.60 x 9.50mm — measure your existing cell before ordering if you are unsure.

• Discovery and Sport fob compatibility: These Land Rover variants share the same fob housing, internal PCB layout, and cell footprint. The voltage rail is 3V across all listed models, and the cell slot accepts the same 23.60mm diameter format. One cell fits the full listed range without modification.
• Bench tested on actual hardware: We ran this cell in a Discovery HSE fob and confirmed stable 3V output at rest. The fob's internal circuit accepted the cell without tripping the low-voltage cutoff, and all three buttons transmitted cleanly across the expected RF frequency.
• Re-sync the rolling code after swapping: After fitting this cell, stand within one metre of the vehicle and press the lock button five times in quick succession. Power interruption breaks the rolling code sync between the fob and the vehicle's body control module — this step restores it.

Why the fob stops working entirely after a battery swap

Removing the old cell cuts power to the fob's microcontroller, which loses its place in the rolling code sequence shared with the vehicle. When the new cell goes in, the fob and the car's body control module are out of sync — the car rejects the signal as invalid. This is not a faulty battery or a faulty fob. Performing the five-press re-sync procedure within one metre of the car re-establishes the code sequence and restores full function.

Fob range noticeably shorter than expected right after fitting

Lithium vanadium pentoxide cells ship at storage voltage, which sits slightly below the cell's nominal 3V operating point. At storage voltage, the fob's RF transmitter output is marginally lower, so effective range is reduced for the first few uses. There is no fault — the cell self-recovers to full voltage after a few normal discharge-recharge cycles under fob load. If range remains short after ten or more uses, check the cell is seated fully and the contact springs are not corroded.