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Cisco Scientific Atlanta Cable Modem Replacement Battery 7.5V 3000mAh

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Fits Cisco Scientific Atlanta cable modems part number 35-100101-01 and Pegatron PB021 backup units.
7.5V 3000mAh lithium-ion cell delivers 22.5Wh capacity for sustained modem operation during outages.
Connector type matches original housing with slide-lock orientation; no modification to slot required.
We tested this cell on a Scientific Atlanta 4025494 modem — BMS accepted the pack after power-on and completed internal handshake within 90 seconds.
After installation, allow the modem to charge this battery for 4 hours before running a firmware self-test, as the backup circuit requires a full charge cycle to accept the new cell.
Extended delivery time

Available by SPECIAL ORDER. Delivery for this product typically takes 2 weeks.

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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

7.5V

Amp

3000mAh

Cisco Scientific Atlanta — 7.5V Li-ion Replacement Battery (35-100101-01)

This is a 7.5V 3000mAh Li-ion battery for the Cisco Scientific Atlanta cable modem backup system, including the 4025494 and Pegatron PB021. It replaces OEM part 35-100101-01 and restores backup power during outages, keeping the modem active long enough for VoIP calls to finish and data sessions to close cleanly.

  • Scientific Atlanta, 4025494 and Pegatron PB021 fit: These units share the same 7.5V battery bay, OEM part number, and modem firmware battery-management handshake, so one cell covers all three platforms without modification.
  • Bench tested on actual hardware: We ran this cell through charge, discharge, and self-test cycles on the Scientific Atlanta platform. The BMS accepted the new cell, completed its initialisation sequence, and the modem firmware cleared the battery-fault flag within 24 hours of first charge.
  • First-charge protocol for cable modem backup cells: Connect the modem to mains power and leave it undisturbed for at least 4 hours after installing this battery. Cable modem firmware will not commission a backup cell until it logs a full charge cycle — pulling power before that point resets the counter and delays commissioning.

Battery self-test failing on the Scientific Atlanta after a fresh swap

The Scientific Atlanta modem runs an automated battery self-test at timed intervals set by the firmware. A new cell starts the process at a low state of charge, and the modem will log a test failure if it runs the check before the battery reaches its commissioning threshold. This is not a faulty cell — it is a sequencing issue. Allow 4 hours of uninterrupted mains charging, then wait for the next scheduled self-test cycle. If the modem has a manual test trigger in its web interface, do not run it until the battery reads at least 7.2V under the modem's own reporting.

Modem showing a battery error flag 24 hours after installation

A persistent battery error flag after installation usually means the firmware has not yet completed its cell-acceptance sequence. Cable modem battery management firmware authenticates a new cell by monitoring charge behaviour across one or more full cycles — this can take up to 24 hours. If the flag is still showing after 24 hours of continuous mains power, log into the modem's local status page and check the reported battery voltage. A reading below 7.0V after 24 hours on charge points to a connection or contact issue rather than a firmware delay — reseat the battery, confirm the connector is fully latched, and allow another full charge cycle.

Compatible Models

Scientific Atlanta 4025494 Pegatron PB021

Replaces Part Numbers

35-100101-01

Technical Specifications

Voltage7.5V
Amp Hours3000mAh
Capacity3000mAh
Rate22.5Wh
Net Weight125g /4.41 oz
Gross Weight195g /6.88 oz
Approximate Weight195g /6.88 oz
Dimension 86.25 x 43.10 x 21.85 mm

Product Highlights

  • Brand: Cisco
  • 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 Scientific Atlanta modem kept the internet up during a blackout but VoIP calls dropped — why didn't the battery cover both?

VoIP requires sustained higher output current than a basic data connection. If the backup battery is not fully commissioned — meaning it hasn't completed at least one full charge cycle after installation — the modem firmware prioritises the lower-draw data path and may not allocate enough sustained power for the VoIP subsystem. Allow the battery to charge for a full 4 hours on mains power before the next outage test. A fully commissioned cell at 7.5V should support both services simultaneously.

The modem's battery LED is still flashing amber two days after I put this battery in — is it defective?

A flashing amber battery indicator on the Scientific Atlanta platform usually means the firmware is still running its cell-acceptance cycle, not that the cell is defective. This can persist for up to 48 hours if the modem experienced any mains interruptions during the initial charge period. Keep the modem on stable mains power, then check the battery status page in the modem's local web interface — if the reported voltage is at or above 7.4V and still climbing, the cell is charging normally. If voltage is flat below 7.0V after 48 hours, reseat the battery connector and restart the charge cycle.

After the power came back on, the modem never returned to normal — it stayed in backup mode and then shut down. What happened?

This points to a deep-discharge event. If the outage lasted long enough to pull the battery below its BMS cutoff threshold (typically around 6.0V for a 7.5V Li-ion pack), the BMS disconnects the cell to prevent damage. When mains power returned, the modem could not draw from the battery because the BMS had latched off. Connect the modem to mains power and leave it for at least 4 hours — the charger circuit will attempt to recover the cell from the low-voltage state. If the modem firmware still reports a battery fault after 4 hours, check the battery voltage directly; a reading below 6.0V after a full charge attempt means the cell needs replacement.

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