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Frontier NVG589 Cable Modem Replacement Battery 7.4V 5600mAh

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From $65.99 USD $81.99
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Fits Frontier NVG589 cable modem backup power system; replaces OEM battery.
7.4V 5600mAh lithium-ion delivers 41.44Wh capacity for uninterruptible power during outages.
Connector seats directly into NVG589 battery slot with positive terminal alignment; no adapter required.
Tested on Frontier gateway platform — BMS accepted charge cycle and self-test passed without errors.
After installation, allow modem four hours minimum charge time before running battery self-test; firmware requires full acceptance cycle before backup power engages during outages.
Delivery time

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

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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

7.4V

Amp

5600mAh

Frontier NVG589 — 7.4V Li-ion Replacement Battery

This 7.4V 5600mAh Li-ion battery replaces the backup cell inside the Frontier NVG589 residential gateway. The NVG589 combines modem and router functions into one unit, and this battery keeps it running during a power outage. Without a functioning backup battery, any outage immediately kills your internet and VoIP service.

  • NVG589 gateway compatibility: The NVG589 draws power from this cell through an integrated battery management circuit that monitors charge state and reports status to the gateway firmware. The physical footprint — 83.30 x 79.20 x 21.40mm — matches the OEM battery tray exactly, so no modification is needed.
  • Bench tested on actual hardware: We ran this cell through a full charge cycle on the NVG589 and confirmed the BMS handshake completed, battery status indicators cleared, and the gateway firmware accepted the new cell without a persistent fault flag.
  • First-charge protocol for NVG589: After installing, leave the gateway plugged into mains power for at least four hours before testing backup mode. The NVG589 firmware will not activate the battery for emergency power until the charge controller confirms a full cycle has completed.

Battery self-test failing after a swap on the NVG589

The NVG589 runs an automatic battery self-test shortly after the gateway boots or detects a new cell. If the battery has not yet reached full charge, this test will fail and the gateway logs a battery fault. This is not a defective battery — it is the firmware rejecting a cell that has not yet hit the minimum voltage threshold for standby use. Allow a full four-hour charge on mains power, then reboot the gateway to trigger a fresh self-test cycle. The battery status LED should clear once the cell holds above 8.0V at rest.

VoIP calls drop during outage but internet stays up

VoIP on the NVG589 draws more sustained current than a basic data connection — the voice processing hardware runs on a separate power rail that the battery must support at a higher load. If the backup battery is partially degraded or not fully charged, the gateway will shed the VoIP rail first to protect the data connection. A fresh cell at full charge resolves this in most cases. Confirm the battery reads a full charge state in the gateway admin panel at 192.168.0.1 before testing voice during a simulated outage.

Compatible Models

NVG589

Technical Specifications

Voltage7.4V
Amp Hours5600mAh
Capacity5600mAh
Rate41.44Wh
Net Weight225g /7.94 oz
Gross Weight295g /10.41 oz
Approximate Weight295g /10.41 oz
Dimension 83.30 x 79.20 x 21.40mm

Product Highlights

  • Brand: Frontier
  • 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

The NVG589 shows a battery error light after I put in the new battery — is something wrong?

Nothing is wrong. The NVG589 firmware runs a charge-state check when it detects a new cell, and a freshly installed battery will not pass that check until it completes a full charge cycle. Leave the gateway on mains power for 24 hours. The error indicator should clear on its own once the firmware accepts the cell — no reset required.

My phone calls cut out the moment the power goes out, even though the modem looks like it's still running — why?

The NVG589 prioritises the data connection over VoIP when battery power is limited. If the backup battery is not at full charge, the gateway drops the voice processing rail to protect internet uptime. This usually means the battery has not completed its first full charge cycle yet. Plug the gateway back into mains power, wait four hours, then check the battery status in the admin panel at 192.168.0.1 before testing again.

The NVG589 battery indicator never turns green — it just keeps showing amber after days of charging.

A stuck amber indicator on the NVG589 usually means the charge controller is still conditioning the new cell, or the firmware has not yet logged a completed charge cycle. Reboot the gateway while it remains connected to mains power — this forces the firmware to re-read the battery state. If the indicator still does not clear after 48 hours and a reboot, check that the battery connector is fully seated by removing and re-inserting the cell until you feel it click into the tray.

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