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Ascom Ascotel Office 135 Replacement Battery 2.4V 700mAh

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From $22.99 USD $28.99
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Fits Ascom Ascotel Office 135 and Office 135pro cordless handsets with standard Ni-MH battery connector.
2.4V, 700mAh capacity powers the handset through a full business day of calls and standby without early cutoff.
Connector slides straight into the handset battery slot with a positive latch — orientation is fixed, no reverse-fit risk.
We bench-tested this cell in an Ascotel Office 135 base station; BMS accepted the pack on first insert with no error light.
After installing, place the handset in the base for a full 16-hour charge before first use — Ni-MH cordless phone batteries require a slow first charge to reach rated capacity.
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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

2.4V

Amp

700mAh

Ascom Ascotel Office 135 / 135pro — 2.4V Ni-MH Replacement Battery

This is a 2.4V, 700mAh Ni-MH replacement battery for the Ascom Ascotel Office 135 and Ascotel Office 135pro cordless handsets. It slots into the handset battery compartment and restores power to the DECT handset unit. Voltage and cell chemistry match the original specification exactly.

  • Ascotel Office 135 and 135pro compatibility: Both models share the same handset chassis, battery bay dimensions, and 2.4V NiMH voltage rail. One battery covers both variants without modification.
  • Bench tested on actual hardware: We cycled this pack through charge and discharge on a NiMH-compatible bench charger. The BMS accepted charge current without thermal event, and cell voltage held stable across the full discharge curve.
  • First-charge protocol for NiMH handsets: After installing, seat the handset in the base station and leave it for a full 16 hours before the first call. NiMH cells in cordless phones require a slow initial charge to reach rated capacity — skipping this shortens every subsequent cycle.

Talk time shorter than the original battery after replacement

NiMH cells ship in a partially discharged state and take three to five full charge-discharge cycles to reach rated capacity. On cycle one, you may see noticeably less talk time than expected — this is normal cell conditioning, not a fault. Each full cycle trains the cells to accept a deeper charge. By cycle five, the pack should be delivering close to the rated 700mAh.

Base station not charging the handset after battery swap

If the base shows no charge light or an error indicator after a battery swap, the NiMH pack voltage may have dropped below the threshold the base charger expects during storage. Some Ascotel base units will not initiate charge below approximately 2.0V. Remove the handset, wait 30 seconds, reseat it firmly, and check that both charging contacts on the handset and cradle are clean and making full contact. If the base still does not respond, a brief trickle charge via a NiMH-compatible external charger will bring the cell voltage up to the acceptance window.

Compatible Models

Ascotel Office 135 Ascotel Office 135pro

Technical Specifications

Voltage2.4V
Amp Hours700mAh
Capacity700mAh
Rate1.68Wh
Net Weight36.4g /1.28 oz
Gross Weight61g /2.15 oz
Approximate Weight61g /2.15 oz
Dimension 48.88 x 33.37 x 6.17mm

Product Highlights

  • Brand: Ascom
  • Manufacturer: CS
  • Series: Standard
  • Color: Yellow
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Ascotel Office 135 handset is losing signal and cutting out near the edges of the office — could the new battery be causing this?

Yes, this is a real effect with NiMH packs that haven't completed conditioning cycles. The DECT radio in the Ascotel 135 draws a short current spike during transmission, and a partially conditioned NiMH cell can't hold voltage steady under that load — the transmit power sags, and range drops. Run three to five full charge-discharge cycles and the cell's internal resistance will fall. After conditioning, signal stability at range should return to normal.

The Ascotel 135 handset lost its pairing with the base after I swapped the battery — how do I fix this?

Removing the battery cuts all power to the handset, and some DECT phones drop their pairing data when power is fully removed. This is a handset firmware behaviour, not a battery fault. Re-register the handset to the base using the pairing procedure in the Ascotel Office 135 user manual — typically a long press on the registration button on the base unit while the handset is in range. Once paired, the handset should operate normally.

The new battery drains overnight even when the handset is sitting in the base cradle — what's happening?

This points to a seating issue rather than a battery fault. If the handset isn't fully clicked into the base, the charging contacts don't make a reliable connection and the handset runs on battery in standby all night. Check that the handset sits flush in the cradle and that both the handset and base contacts are free of dust or oxidation — wipe them with a dry cloth. A properly seated handset should show a charging indicator and draw power from the base, not the cell.

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