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VTech 5829 Cordless Phone Replacement Battery 3.6V 700mAh

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From $21.99 USD $27.99
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Fits V Tech models 5829, 5839, 5851, 5859 and replaces OEM part numbers 80-0099-00-00, 80-1323-00-00, 89-1323-00-00.
3.6V Ni-MH 700mAh pack delivers the voltage and capacity this handset needs for wireless range away from the base station.
Connector slides onto the battery contacts inside the handset compartment with a single locking tab that seats flush against the housing.
We bench-tested the pack in a 5829 handset paired to its base — the BMS accepted voltage on first insertion without error codes.
Place the handset in the base for a full 16-hour charge before first use; NiMH batteries need 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.

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

3.6V

Amp

700mAh

V Tech 5829 / 5839 / 5851 / 5859 Series — 3.6V Ni-MH Replacement Battery (80-0099-00-00)

This is a 3.6V, 700mAh Ni-MH battery for V Tech cordless phone handsets in the 5829, 5839, 5851, and 5859 series, plus over 79 additional compatible models. It replaces OEM part numbers 80-0099-00-00, 80-1323-00-00, and 89-1323-00-00. The battery slots into the handset compartment and powers the DECT radio and speaker circuitry away from the base station.

  • 5829/5839/5851/5859 platform fit: These handsets share the same 3.6V battery bay, connector polarity, and NiMH charge acceptance profile. The base station charges at a fixed trickle rate matched to this chemistry — swapping in a different voltage or chemistry will cause the charge circuit to behave incorrectly.
  • Bench tested on actual hardware: We ran this cell through the base station charge cycle and confirmed the BMS accepts the incoming trickle current without triggering a fault light. Discharge curves stayed flat across the rated capacity window before the protection circuit cut off at the low-voltage floor.
  • First charge on NiMH cordless handsets: After installing, seat the handset in the base and leave it for a full 16 hours before use. NiMH cells shipped from storage have partially self-discharged — a slow first charge cycles the cell chemistry to rated capacity. Skipping this step shortens talk time from the first day.

Talk time shorter than the original battery after replacement

NiMH cells need three to five full charge-discharge cycles before they reach rated capacity. A new battery will feel weaker than the old original in the first few days — this is normal cell conditioning, not a fault. Each full cycle builds the electrochemical capacity closer to the rated 700mAh. Run the handset until it powers down, return it to the base for a full charge, and repeat for at least three cycles.

Base station showing no charge or error light after swap

Batteries stored in a warehouse can self-discharge below the threshold the base station accepts as a valid NiMH pack. When the terminal voltage is too low, the base charge circuit reads it as a fault and refuses to begin the charge cycle. Place the handset in the base and leave it undisturbed for at least 30 minutes — most base stations will attempt a recovery trickle at around 1.0V per cell. If the error light clears, the charge cycle has started; leave the handset in the base for the full 16-hour initial charge.

Compatible Models

5829 5839 5851 5859 6725 6763 6765 6772 6773 6775 6783 6785 6803 6807 6820 6821 6861 6866 6870 6872 6879 6880 6882 6889 6897 8900990000 8913230000 i6717 i6727 i6757 i6767 i6777 i6778 i6787 i6788 i6789 27910 5822 ia5823 ia5829 ia5839 ia5845 ia5849 ia5851 ia5859 ia5875 5939 i6720 i6725 i6735 i6763 i6764 i6765 i6772 i6773 i6775 i6783 i6785 i6786 MI6803 MI6807 i6820 MI6820 i6821 MI6821 i6822 MI6822 i6861 MI6861 MI6862 MI6866 MI6870 MI6872 MI6873 MI6877 MI6879 MI6882 MI6885 MI6889 MI6896 MI6897 6822BAT DS4121

Replaces Part Numbers

80-0099-00-00 80-1323-00-00 89-1323-00-00

Technical Specifications

Voltage3.6V
Amp Hours700mAh
Capacity700mAh
Rate2.52Wh
Net Weight36.7g /1.29 oz
Gross Weight61.7g /2.18 oz
Approximate Weight61.7g /2.18 oz
Dimension 45.90 x 31.20 x 10.70mm

Product Highlights

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

Frequently Asked Questions

My V Tech handset is losing range after I put in the new battery — calls cut out as I walk away from the base. What's causing this?

NiMH voltage sags under the RF transmit load when the cells haven't been fully conditioned yet. The DECT radio in the 5829/5859 series needs a stable voltage rail to sustain transmit power — a partially charged or unconditioned NiMH pack drops voltage mid-transmission and the radio backs off its range. Run three full charge-discharge cycles first: use the handset until it powers down, then charge for 16 hours in the base. After the third cycle, the voltage sag under RF load reduces significantly.

My handset lost its pairing with the base after I swapped the battery. How do I get it back?

Removing the battery completely cuts power to the handset's memory — some DECT phones in the 5829/5859 series drop their base pairing when power is fully removed. This is a phone firmware behaviour, not a battery fault. Re-register the handset manually: on most V Tech models, press and hold the FIND HANDSET button on the base for four seconds, then go into the handset menu and select Register Handset. Consult your model's manual for the exact menu path if the prompt doesn't appear automatically.

The battery drains overnight even though the handset is sitting in the base. Is the battery faulty?

A battery draining overnight usually means the handset isn't making a solid electrical connection with the base charging contacts. Check that the handset is fully seated — even a slight tilt or debris on the charging pins will stop the trickle charge while the standby circuitry keeps drawing current. Clean the gold contacts on both the handset and the base cradle with a dry cloth, reseat the handset, and confirm the charge indicator light comes on within 60 seconds of placing it in the base.

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