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Harman/Kardon Onyx Studio 7 Replacement Battery GSP-1S1P-OS7A

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From $38.99 USD $47.99
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Fits Harman/Kardon Onyx Studio 7; replaces GSP-1S1P-OS7A battery pack.
Delivers 3.7V, 3350mAh output; sustains amplifier and Bluetooth radio under sustained playback.
Uses standard cylindrical cell with solder tabs; seats into existing holder without modification.
Bench testing showed stable voltage under 2A discharge; BMS accepted charge cycle without fault codes.
On first use, discharge the speaker below 20% before topping off to establish accurate fuel gauge calibration.
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.7V

Amp

3350mAh

Harman/Kardon Onyx Studio 7 — 3.7V Li-ion Replacement Battery (GSP-1S1P-OS7A)

This is a 3.7V, 3350mAh Li-ion cell replacement for the Harman/Kardon Onyx Studio 7 Bluetooth speaker. It fits the Onyx Studio 7 only — not earlier Studio models. Capacity is 3350mAh (12.4Wh), matching the original cell specification.

  • Onyx Studio 7 fitment: The Studio 7 uses a single-cell Li-ion pack with a proprietary connector and a fuel gauge IC that reads state-of-charge from the cell's voltage curve. A replacement cell must match the 3.7V nominal voltage and report the correct capacity range, or the indicator ring will misread from the first charge cycle.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Studio 7 mainboard. The BMS accepted the pack without fault codes, the fuel gauge calibrated correctly, and the amplifier drew cleanly through high-volume bursts without triggering undervoltage protection.
  • Fuel gauge maintenance for daily use: The Onyx Studio 7 sits on desks and gets topped off constantly. Charge to 100%, then let it discharge below 20% at least once a month before plugging back in. Skipping this causes the fuel gauge IC to drift, so the speaker shuts off at what it reports as 30% charge.

Audio distortion before the battery indicator reaches empty on the Studio 7

The Studio 7 amplifier pulls a short, high-current spike on loud transients — bass hits and drum attacks in particular. When the cell's internal resistance rises with age, that spike causes a voltage sag below 3.2V, which the amplifier reads as low supply and clips the output. The battery indicator can still show two bars when this starts happening. A fresh cell with lower internal resistance eliminates the sag and stops the clipping at the source.

Studio 7 not waking from USB-C after the battery fully drained

If the Studio 7 discharges completely and sits for several days, the cell voltage can fall below 2.5V. At that level, the USB-C PD controller will not negotiate a charging contract — the port looks dead and nothing happens when you plug in. To recover, use a charger that outputs a constant 5V without PD negotiation, leave it connected for at least 20 minutes, and the BMS pre-charge circuit will trickle current into the cell until it crosses 2.9V and normal charging resumes.

Compatible Models

Onyx Studio 7

Replaces Part Numbers

GSP-1S1P-OS7A

Technical Specifications

Voltage3.7V
Amp Hours3350mAh
Capacity3350mAh
Rate12.4Wh
Net Weight54g /1.90 oz
Gross Weight124g /4.37 oz
Approximate Weight124g /4.37 oz
Dimension 76.50 x 19.50 x 19.50mm

Product Highlights

  • Brand: Harman/Kardon
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Onyx Studio 7 plays fine for a while then Bluetooth keeps cutting out at high volume — is that a speaker fault or the battery?

That's a battery symptom, not a speaker fault. At high volume, the amplifier and Bluetooth radio draw current simultaneously, and a degraded cell can't sustain the combined load without voltage sag. The BMS detects the sag and throttles output to protect the cell, which drops the radio link first because audio amplification holds priority. Replacing the cell resolves this — a fresh 3350mAh pack at 3.7V nominal handles the combined amp-plus-radio draw without sagging.

The Studio 7 shows a full charge on the LED ring but shuts off after less than an hour of use — what's causing that?

This is fuel gauge drift from shallow cycling. If the speaker is regularly topped off before dropping below 50%, the fuel gauge IC loses track of the real capacity and reports full when the cell is already partly depleted. The fix before swapping the battery is one full discharge below 20% followed by an uninterrupted charge to 100% — this recalibrates the gauge. If the problem persists after two recalibration cycles, the cell itself has degraded and needs replacing.

The Studio 7 gets noticeably warm on the bottom and sides during long listening sessions — is that a sign the battery is failing?

Some warmth is normal — the amplifier and the discharging Li-ion cell both generate heat, and the fabric housing traps it. The concern is when it becomes hot to the touch or the speaker reduces volume on its own during extended play. That combination means the thermal protection is activating, usually because a degraded cell is generating more heat per milliamp drawn than a healthy one should. Check by feeling the housing after 30 minutes at moderate volume — warm is expected, hot enough to make you pull your hand back is not, and at that point the cell should be replaced.

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