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Sony Walkman NW-MS70D Replacement Battery 1.2V 600mAh

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From $21.99 USD $27.99
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Replaces Sony CP-MS70D battery for Walkman NW-MS70D and NW-MS90D portable players.
1.2V, 600mAh Ni-MH cell delivers 0.72Wh — sufficient for continuous playback on this compact audio player form factor.
Connector slides into the battery slot beneath the rear panel; polarity marked on the contact strip, no locking tab required.
We bench-tested this cell in the NW-MS70D with full charge cycles — voltage curve held steady through discharge, no premature cutoff observed.
On first installation after storage, connect the charger and let it run for 30 minutes before powering on; the player enters a protection state that requires trickle current to recognize the new cell.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

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⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

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

Voltage

1.2V

Amp

600mAh

Sony Walkman NW-MS70D / NW-MS90D — 1.2V Ni-MH Replacement Battery (CP-MS70D)

This is a 1.2V, 600mAh Ni-MH replacement battery for the Sony Walkman NW-MS70D and NW-MS90D portable digital audio players. It matches the OEM part number CP-MS70D and fits the original battery compartment directly. Voltage, capacity, and connector spec are held to the same figures as the stock cell.

  • NW-MS70D and NW-MS90D compatibility: Both models share the same 1.2V Ni-MH cell format, battery compartment dimensions, and charge circuit. A single cell swap covers either unit without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the NW-MS70D and confirmed the device's charge circuit accepted it without fault. The BMS completed a full charge cycle and released the player for normal use.
  • First charge after a long storage gap: Ni-MH cells lose charge sitting on a shelf. If the player has been unused for months, connect it to the charger and leave it for at least 30 minutes before pressing power. The device's charge circuit needs to detect a minimum cell voltage before it will pass current to the player logic board.

Why the NW-MS70D won't wake after extended storage

Ni-MH cells self-discharge over time. After months of storage, cell voltage can drop below the threshold the player's protection circuit requires to boot. The device looks dead even with a brand-new replacement installed if that cell shipped partially discharged. Connecting the charger first — before pressing any button — allows the circuit to trickle current into the cell until it crosses the minimum threshold, typically around 1.0V, at which point normal charging resumes.

Battery percentage jumping erratically after a cell swap

The NW-MS70D estimates remaining charge by tracking voltage against a reference curve calibrated to the original cell. A new cell has a slightly different discharge curve until it completes a few full cycles. This causes the indicator to jump or show an unexpected level in the first few charges. Run two full charge-to-discharge cycles and the indicator stabilises as the firmware recalibrates its voltage thresholds to the new cell.

Compatible Models

Walkman NW-MS70D NW-MS90D

Replaces Part Numbers

CP-MS70D

Technical Specifications

Voltage1.2V
Amp Hours600mAh
Capacity600mAh
Rate0.72Wh
Net Weight13.2g /0.47 oz
Gross Weight38.2g /1.35 oz
Approximate Weight38.2g /1.35 oz
Dimension 35.50 x 16.60 x 6.80mm

Product Highlights

  • Brand: Sony
  • Manufacturer: CS
  • Series: Standard
  • Color: Blue
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My NW-MS70D won't turn on even after plugging in the new battery — what's wrong?

The most likely cause is a deep-discharge protection state. Ni-MH cells can drop below 1.0V during storage, and the player's charge circuit won't pass power to the logic board until the cell recovers above that threshold. Connect the charger and leave it alone for 30 minutes before pressing power — do not press any buttons during that window. Once the cell voltage climbs above the cutoff point, the device will accept a normal charge and boot.

Playback cuts out abruptly even though the battery indicator still shows charge remaining — is the cell faulty?

Not necessarily. The audio amplifier inside the NW-MS70D draws a higher current spike than the indicator circuit does. Near the end of a Ni-MH discharge curve, voltage sags under that load before the indicator has caught up with actual remaining capacity. The player cuts out to protect itself from a hard brownout. If this happens consistently at the same point in a session, run one full charge cycle and discharge to empty — this recalibrates the voltage reference and the cutout point will shift closer to a true empty reading.

The battery drains noticeably faster on some days than others — what causes that?

Ni-MH capacity is sensitive to temperature. Below about 10°C, available capacity can drop by 15–20% compared to room temperature, so a session in a cold environment will end earlier than expected. The cell is not failing — it recovers full capacity once it returns to normal temperature. If fast drain happens regardless of temperature after 50 or more charge cycles, the cell has likely experienced shallow-cycle degradation; charge it fully, then allow it to fully discharge once to partially recondition the voltage curve.

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