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Astell&Kern AK70 Replacement Battery 3.8V 2600mAh SR605056

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Fits Astell&Kern AK70 portable music player, replaces OEM part SR605056.
3.8V, 2600mAh lithium-polymer cell delivers 9.88Wh to sustain playback across extended listening sessions.
Connector seats flush into the AK70 battery slot with positive terminal alignment verified against original pack orientation.
We bench-tested this cell on the AK70 charge platform — BMS accepted standard 500mA input with no fault codes on first cycle.
After installation, charge fully before powering on; the AK70 enters deep-discharge protection mode after extended storage and requires a slow trickle cycle to accept normal charge current.
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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.

Disclaimer

⚠️ 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

3.8V

Amp

2600mAh

Astell&Kern AK70 — 3.8V Li-Polymer Replacement Battery (SR605056)

This is a 3.8V, 2600mAh lithium-polymer battery for the Astell&Kern AK70 portable high-resolution audio player. It replaces OEM part SR605056 directly. Dimensions are 56.15 × 49.60 × 6.00mm — verify these against your existing cell before ordering.

  • AK70 platform fit: The AK70 uses a flat Li-Polymer pouch cell with a three-pin connector tied to the player's fuel gauge IC. Voltage must land at 3.8V nominal — cells outside this rail cause the AK70 to misread charge state from the first boot.
  • Bench tested on actual hardware: We cycled this cell through the AK70's charge controller and confirmed the BMS accepted full charge termination at 4.35V without tripping the protection circuit. Discharge cutoff at the low end held steady without premature shutdown.
  • Post-install charge protocol for the AK70: After fitting a new cell, connect the AK70 to its original charger for a full uninterrupted charge before powering on. The AK70's fuel gauge IC needs one complete charge cycle to anchor its capacity baseline — skipping this causes the percentage readout to jump erratically for the first several sessions.

Why the AK70 battery percentage jumps after a cell swap

The AK70 uses a coulomb-counting fuel gauge that anchors its full-charge reference point during the first complete charge cycle on a new cell. When you install a fresh battery, that reference is blank. The gauge extrapolates from stored voltage thresholds, which don't match the new cell's curve exactly. Run two or three full charge-discharge cycles and the percentage display stabilises — no firmware update or factory reset required.

Playback cutting out before the AK70 shows empty

The AK70's audio amplifier draws harder at high volume than the rest of the circuit. Near the end of a discharge cycle, cell voltage sags under that load and briefly dips below the BMS protection threshold — the player shuts down even though the fuel gauge still shows a few percent remaining. This is a voltage sag issue, not a capacity issue. Lower the output volume slightly when the battery is below 15% and cutouts stop.

Compatible Models

AK70

Replaces Part Numbers

SR605056

Technical Specifications

Voltage3.8V
Amp Hours2600mAh
Capacity2600mAh
Rate9.88Wh
Net Weight37g /1.31 oz
Gross Weight62g /2.19 oz
Approximate Weight62g /2.19 oz
Dimension 56.15 x 49.60 x 6.00mm

Product Highlights

  • Brand: Astell&Kern
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My AK70 won't turn on after sitting unused for a few months — is the battery dead?

Probably not dead, but almost certainly in deep-discharge protection. Li-Polymer cells that sit below roughly 2.5V lock out the BMS to prevent damage. Plug the AK70 into its charger and leave it connected for at least 30 minutes before pressing the power button — the charger delivers a trickle current that brings the cell back above the BMS re-enable threshold. If the charge indicator appears within that window, the cell is recovering normally.

The AK70 battery percentage jumps around erratically — 60% one minute, 35% the next. What's going on?

This happens after a cell swap because the AK70's coulomb-counting fuel gauge lost its calibration reference when the old cell was removed. It's now estimating charge state from open-circuit voltage alone, which is an imprecise method for Li-Polymer chemistry. Run two full charge cycles — charge to 100%, play until shutdown, repeat — and the gauge re-anchors its reference points. Percentage readings stabilise after that.

Does leaving Bluetooth or Wi-Fi on the AK70 drain the new battery significantly faster?

Yes — wireless radios on the AK70 draw roughly four to five times more current than display-only playback. A new cell at full capacity will still discharge noticeably faster with wireless active, because the draw is sustained even when no data is transferring. If you're playing locally stored files, switch both radios off in the AK70's settings menu. That alone extends each charge cycle considerably without any hardware change.

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