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Telekom Comfort Pro CM 500 Replacement Battery 3.7V 800mAh

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New arrival
From $33.99 USD $41.99
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Fits Telekom Comfort Pro CM 500 and CM 510 cordless phone handsets as OEM replacement.
3.7V 800mAh Li-ion cell delivers the same energy density as the original pack for full-day standby and talk time.
Connector slots onto the handset battery contacts with a plastic retention clip; orientation is keyed and only fits one way.
We charged the cell through a Telekom base station — BMS accepted the pack on first insertion with no fault delay.
After installing, seat the handset in the base for a full 16-hour charge before first use; Li-ion packs reach rated capacity after the slow initial charge cycle on DECT platforms.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

800mAh

Telekom Comfort Pro CM 500 / CM 510 — 3.7V Li-ion Replacement Battery

This is a 3.7V 800mAh Li-ion battery for the Telekom Comfort Pro CM 500 and CM 510 cordless DECT handsets. It replaces the original cell when the handset no longer holds a charge or drops calls due to low voltage. Dimensions are 55.00 × 34.00 × 4.00mm — measure your current cell before ordering if you are unsure.

  • CM 500 and CM 510 compatibility: Both models share the same handset chassis, battery bay dimensions, and 3.7V supply rail. One cell fits both without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the CM 500 platform. The protection circuit tripped correctly at the low-voltage cutoff and accepted a full charge from the base station without error.
  • First charge after installation: Li-ion cells ship partially charged but not full. Seat the handset in the base immediately after installation and leave it for a complete charge cycle before use — this lets the BMS calibrate its state-of-charge tracking against the new cell's actual capacity.

Talk time shorter than expected after fitting a new cell

A Li-ion cell straight from storage often reads a partial state of charge that the BMS accepts without running a full cycle. The handset's fuel gauge can misread remaining capacity for the first one or two cycles until the BMS has tracked a complete charge and discharge. Run the handset down to the low-battery warning, then charge it fully in the base — repeat this once more if talk time still feels short. After two full cycles, reported capacity should align with the 800mAh rating.

Handset loses DECT pairing after battery replacement

Removing the old battery cuts all power to the handset, which can erase the stored base station pairing on some DECT phones. The CM 500 and CM 510 store pairing data in volatile memory that resets on a hard power loss. To re-register, hold the handset's page or register button while the base is in pairing mode — consult the base station label for the exact sequence. Once registered, the handset reconnects to the base normally and retains the pairing through subsequent battery swaps as long as the cell is not removed again.

Compatible Models

Comfort Pro CM 500 Comfort Pro CM 510

Technical Specifications

Voltage3.7V
Amp Hours800mAh
Capacity800mAh
Rate2.96Wh
Net Weight19.4g /0.68 oz
Gross Weight44g /1.55 oz
Approximate Weight44g /1.55 oz
Dimension 55.00 x 34.00 x 4.00mm

Product Highlights

  • Brand: Telekom
  • 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 Telekom CM 500 handset shows low battery almost immediately after a full charge — is the new cell faulty?

Not necessarily. A Li-ion cell that has sat in storage can have a shifted BMS reference point, causing the handset to report low voltage before the cell is genuinely depleted. Run the handset down to the automatic low-battery cutoff, then place it on the base for a complete charge — do this twice. If the handset still cuts out early after two full cycles, check that the battery contacts in the bay are clean and making firm contact; a weak connection causes a voltage drop that the BMS reads as a depleted cell.

The base station charge light does not come on when I seat the handset after fitting the new battery — what's wrong?

The base checks for a minimum voltage on the charge contacts before starting the charge cycle. A Li-ion cell shipped at a very low state of charge may fall below that threshold. Leave the handset seated for 10–15 minutes without moving it — the base will often begin trickle charging once the contact voltage stabilises. If the light still does not activate, remove the handset, clean the gold charge contacts on both the handset and base with a dry cloth, then reseat firmly; dirty contacts are the most common cause of a missed charge handshake.

My CM 510 handset drains overnight even when it's sitting in the base — why?

This is a standby draw issue, not a battery fault. If the handset is not fully and squarely seated in the base cradle, the charge contacts lose connection and the handset runs on battery rather than drawing from the mains. Lift the handset out, inspect the cradle for debris, and reseat it until you feel or hear it click into position. Confirm the charge light activates on the base — if it does, overnight drain will stop.

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