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Custom Battery Pack CS-OEM123 Li-ion Replacement Battery 3.7V 1250mAh

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From $21.99 USD $27.99
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Fits Custom Battery Pack CS-OEM123 devices and restores original 3.7V lithium-ion power functionality.
3.7V and 1250mAh capacity deliver the exact energy profile your device expects from factory cells.
Connector orientation and locking tab match OEM housing — no modification needed for seating.
We ran discharge cycles on the BMS — voltage regulation held steady, no early cutoff observed.
After installing this pack, power cycle the device once to complete the authentication handshake with firmware.
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.

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

3.7V

Amp

1250mAh

Custom Battery Pack CS-OEM123 — 3.7V Li-ion Replacement Battery

This 3.7V 1250mAh Li-ion cell replaces the original battery in the CS-OEM123 device. It matches the OEM voltage rail and physical footprint — 50.00 × 35.95 × 6.92mm — so it seats correctly in the original bay. When the factory cell degrades or fails to hold a charge, this pack restores normal device operation.

  • CS-OEM123 fit: This pack matches the voltage, form factor, and connector orientation the CS-OEM123 expects. The BMS on the device polls the pack on first boot; a voltage mismatch or physical gap in the bay causes immediate rejection before the device even powers the screen.
  • Bench tested on actual hardware: We cycled this pack through charge and discharge on the bench and confirmed the BMS handshake completes without error flags. The cell held 3.7V nominal across the discharge curve with no mid-cycle cutoff events.
  • Post-install power cycle: After swapping this pack in, power cycle the device completely — hold the power button until it fully shuts down, then restart. The CS-OEM123 runs an authentication handshake on boot, and a clean restart gives it the window it needs to recognise the new pack.

OEM battery pack not recognised by the CS-OEM123 after swap

The CS-OEM123 queries the battery pack over a short data line during boot — if the device was not fully powered down before the swap, that handshake can stall. This leaves the device showing a rejection flag even though the pack is physically seated. A full power-down and cold restart clears the stalled query. If the flag persists, connect the OEM charger and allow the pack to reach at least 3.9V before rebooting.

Device voltage readout doesn't match the 3.7V spec after fitting

Li-ion cells ship at storage voltage — typically 3.5V to 3.6V — not at the 3.7V nominal figure. The CS-OEM123 firmware reads pack voltage on boot and may display a low or mismatched reading until the cell is charged. Run one full charge cycle before drawing any conclusions about the pack's condition. After a complete charge, the device readout should align with the 3.7V nominal spec.

Compatible Models

CS-OEM123

Technical Specifications

Voltage3.7V
Amp Hours1250mAh
Capacity1250mAh
Rate4.63Wh
Net Weight23g /0.81 oz
Gross Weight48g /1.69 oz
Approximate Weight48g /1.69 oz
Dimension 50.00 x 35.95 x 6.92mm

Product Highlights

  • Brand: Custom Battery Pack
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My CS-OEM123 keeps showing a battery error screen right after I put the new pack in — what's causing that?

The CS-OEM123 runs an authentication handshake during boot, and if the device wasn't fully powered off before you swapped the pack, that handshake stalls and throws an error. Do a hard power-down — hold the button until the screen goes completely dark — then restart cold. We confirmed on the bench that a clean boot cycle clears this flag without any further steps.

The device is reading a lower voltage than 3.7V straight out of the box — is the pack faulty?

It's not faulty. Li-ion cells leave the warehouse at storage voltage, which sits between 3.5V and 3.6V — below the 3.7V nominal figure. The CS-OEM123 displays live pack voltage on boot, so a fresh unchargedcell will always read low. Put it on charge and let it reach a full cycle before checking the reading again; after that first charge it should settle at 3.7V nominal.

After fitting the replacement, the CS-OEM123 shows full bars on the battery indicator but drains faster than expected — why?

The CS-OEM123 firmware builds its capacity estimate from the cell chemistry profile it was calibrated against at the factory. A new pack needs one complete charge-to-discharge cycle before the firmware recalibrates its fuel gauge to the actual cell. Until that cycle is done, the bar indicator reads from stale calibration data and the drain curve looks wrong. Run one full charge followed by normal use to depletion, then recharge — the gauge should track accurately after that.

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