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Rectangular lithium-polymer battery pack with wires and connector, includes small installation tool

MPF Products

MPF Products 800mAh 603040 Battery for Marshall Mid Major II III Headphones

SKU CH-TXQM-WB8XE

Replacement 3.7V 800mAh lithium-polymer pack for Marshall Mid, Major II and Major III headphones, includes installation tool

  • Product typeAccessories
  • Restores wireless playtime with 800 mAh capacity
  • Matches original 3.7 V 2.96 Wh spec exactly
  • Fits Marshall Mid, Major II and Major III models
  • Replaces part numbers 603040, SR603040 and VDL603040
  • Includes free installation tool for easier replacement

Compatible replacement battery

This 3.7V lithium-polymer pack replaces the original 603040 cell in Marshall Mid, Major II and Major III Bluetooth headphones. It delivers 800mAh and 2.96Wh to restore wireless runtime. An installation tool is included for the repair.

Buyers needing a drop-in fix

The pack suits owners of the listed Marshall models who are comfortable opening the earcup and soldering the new cell. Buyers who want a plug-and-play module without soldering or who use other headphone brands should look elsewhere.

Capacity and voltage match

The 800mAh rating at 3.7V matches the factory specification so the headphone’s fuel gauge and charge circuit behave as designed. A different capacity would change reported battery life and charging behaviour.

How it compares

Measured against everything we stock in Earbuds & Over-Ear Headphones, at today’s prices. Recalculated every night.

Price $5.99
Cheaper than about 97% of the 7,078 comparable items (median $25.99).

Specifications

Product
Product typeAccessories

Questions about this item

How long will the 800mAh capacity keep my Marshall Major III running under constant playback?

The 800mAh lithium-polymer pack delivers 2.96Wh at 3.7V, matching the original specification for Marshall MID, Major II and Major III models. Actual runtime depends on volume level and Bluetooth codec used.

Does the battery generate noticeable heat or noise during a full day of wireless listening?

Lithium-polymer cells produce no audible noise and only slight warmth during normal charge and discharge cycles. The pack fits inside the earcup exactly as the factory unit did, so thermal behaviour is unchanged.

What tools do I already need to install this 603040 pack in my Major II headphones?

The box includes a plastic opening tool for prying the earcup open. You must supply your own soldering iron and solder to connect the two leads to the headphone circuit board.

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