We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Rectangular lithium-ion battery pack with black plastic casing and gold connector pins

TAURKENAM

TAURKENAM HK-OS4 3500mAh 3.7V lithium-ion battery

SKU CH-FTNS-3WQZ2

Replacement lithium-ion battery for Harman Kardon Onyx Studio 1‑4, 3500 mAh at 3.7 V, includes screwdriver tool

  • Battery TypeLithium-Ion
  • Replacement power for Harman Kardon Onyx Studio 1‑4
  • 3500 mAh capacity extends portable playback time
  • 7 V lithium‑ion chemistry delivers stable output
  • Built‑in overcurrent, overcharge, overvoltage, overheating and short‑circuit protection
  • Screwdriver tool included for straightforward battery swap

Compatible Harman Kardon Onyx Studio replacement

This 3500 mAh lithium-ion battery replaces the original cell in Harman Kardon Onyx Studio 1 through 4 speakers. It delivers 3.7 V nominal voltage and is sold new for owners who need portable playback again.

Installation ease and common pitfalls

A screwdriver set is included so the back cover can be removed and the pack swapped without extra tools. The connector matches the factory plug, but forcing it backwards can bend pins; align the key before pressing. Over-tightening the case screws may crack the plastic posts.

Capacity headroom and limits

At 3500 mAh the pack restores the speaker’s rated runtime for typical indoor listening volumes. Higher output levels or continuous outdoor use will drain it faster, and the built-in protection circuit will cut power if the cell overheats or is shorted. It is not a higher-capacity upgrade and cannot extend playtime beyond the original specification.

Highlights

  • Replacement power for Harman Kardon Onyx Studio 1‑4
  • 3500 mAh capacity extends portable playback time
  • 7 V lithium‑ion chemistry delivers stable output
  • Built‑in overcurrent, overcharge, overvoltage, overheating and short‑circuit protection
  • Screwdriver tool included for straightforward battery swap

Specifications

Battery TypeLithium-Ion

Questions about this item

How can I tell the 3500mAh 3.7V battery is working after I install it?

The speaker should power on and hold a charge for its normal playback time; the built-in overcurrent, overcharge, overvoltage, overheating and short-circuit protections operate automatically.

What comes in the box and what must I buy separately?

The package includes one HK-OS4 battery and one screwdriver tool set; no other parts or tools are required for the replacement.

Which version of this battery fits my Harman Kardon Onyx Studio speaker?

The HK-OS4 is compatible with Onyx Studio 1, 2, 3 and 4, so the single listed version covers all four models.

Also in this aisle

People compared these

Same shelf, same checkout — eight coins and a 30-minute rate lock.