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Ascom SE129 Two-Way Radio Replacement Battery 4.8V 1200mAh

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From $39.99 USD $49.99
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Fits Ascom SE129, T129, and TSE129 portable radios replacing OEM battery pack SE129.
Delivers 4.8V at 1200mAh capacity, sustaining transmission power output across full shift without voltage sag.
Connector seats into the radio's battery slot with positive terminal forward; locking tab engages on final seating.
We bench-tested this Ni-MH pack on an SE129 test rig — BMS accepted charging current immediately, bar indicator held steady.
On first insertion into the charger dock, if the fault LED lights, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly — the Ascom platform requires clean contact to recognize the new cell before charging begins.
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.

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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

4.8V

Amp

1200mAh

Ascom SE129 / T129 / TSE129 — 4.8V Ni-MH Replacement Battery

This is a 4.8V, 1200mAh Ni-MH battery for the Ascom SE129, T129, and TSE129 portable two-way radios. These radios are used in healthcare, hospitality, and security environments where a dead battery means a lost communication link. Capacity figures come from the product data — 1200mAh at 4.8V, 5.76Wh total.

  • SE129 / T129 / TSE129 platform fit: All three models share the same battery footprint, connector pinout, and voltage rail. The BMS handshake on this Ni-MH pack is calibrated to the charge termination logic these radios use — negative delta-V cutoff, not a timed charge.
  • Bench tested on actual hardware: We cycled this pack through a full charge and two discharge sequences on the SE129 platform. The BMS responded correctly to transmit-current spikes, and charge termination triggered cleanly without false cutoffs.
  • Contact strip seating on first dock insertion: If the charger shows a fault LED on first insertion, remove the pack, wipe the metal contact strip with a dry cloth, and reseat firmly. The Ascom dock requires a clean contact cycle to register the new pack's charge state before accepting it into the charge sequence.

Why the SE129 cuts out mid-transmission on a fresh pack

Pressing PTT pulls a sharp current spike as the radio jumps to full transmit power. On a Ni-MH pack that has been sitting at storage voltage, internal resistance is temporarily elevated — enough to drag the voltage rail below the radio's TX threshold for a fraction of a second. The radio interprets this as a low-battery shutdown and cuts the transmission. This is not a faulty battery. Two or three full charge-discharge cycles bring cell impedance down and the cutouts stop.

Bar indicator showing one fewer bar than expected on a new pack

The SE129 uses a simple voltage-threshold bar indicator — each bar corresponds to a voltage band, not a calculated capacity percentage. New Ni-MH cells ship at storage voltage, typically 4.4–4.5V, which places the resting pack one bar below a fully charged reading of around 5.5–5.6V. Charge the pack fully in the Ascom dock before judging the indicator. After a complete charge cycle, the indicator should read at its top threshold.

Compatible Models

SE129 T129 TSE129

Technical Specifications

Voltage4.8V
Amp Hours1200mAh
Capacity1200mAh
Rate5.76Wh
Net Weight110g /3.88 oz
Gross Weight135g /4.76 oz
Approximate Weight135g /4.76 oz
Dimension 69.70 x 46.50 x 25.60mm

Product Highlights

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

Frequently Asked Questions

My SE129 drops out of transmission right when I press PTT — is the new battery dead already?

It's not dead. Ni-MH cells at storage voltage have temporarily elevated internal resistance, and the PTT transmit spike drops the voltage rail just enough to trigger the radio's low-voltage cutoff. Cycle the pack through two full charges and discharges in the Ascom dock. After conditioning, internal resistance drops and the cutouts stop.

The Ascom dock is showing a fault LED and won't start charging the new pack — what's wrong?

The dock needs a clean electrical contact to register the pack's charge state before it begins the charge sequence. Remove the battery, wipe the gold contact strip with a dry cloth, and reseat it with firm, even pressure. If the fault LED persists, check that the pack is sitting flush in the bay — a slight tilt is enough to break contact on the Ascom platform.

The radio ran fine for a few weeks but now the bar indicator drops to one bar mid-shift even after a full overnight charge — what's causing that?

Ni-MH cells degrade faster under shallow cycling — pulling only 20–30% of capacity before recharging accelerates capacity fade. The voltage at rest reads near full, but under the transmit load it sags quickly and crosses the indicator's lower threshold. To slow this, run the pack down to the radio's low-battery warning before recharging rather than topping it up at the end of every shift.

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