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Casio PM38BAT Cordless Phone Replacement Battery 3.6V 700mAh

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From $26.99 USD $32.99
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Fits Casio cordless phone models PM38BAT, PMP3815, PMP3850-PLUGIN, and PMP3860 handsets.
3.6V, 700mAh Ni-MH chemistry delivers enough capacity for typical daily standby and talk cycles.
Connector slides straight into the handset battery slot with a positive contact tab alignment.
We bench-tested voltage recovery after a full discharge cycle — BMS accepted charging without fault codes.
After installing, place the handset in the base for a full 16-hour charge before first use — NiMH 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.

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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.6V

Amp

700mAh

Casio PM38BAT / PMP3815 / PMP3860 Series — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 700mAh Ni-MH rechargeable battery for Casio cordless handsets including the PM38BAT, PMP3815, PMP3850-PLUGIN, and PMP3860. It slots into the handset battery compartment and connects directly to the charging circuit. Dimensions are 45.60 × 31.30 × 10.60mm — verify these against your existing cell before ordering.

  • Compatible across the PM38/PMP38 handset range: These models share the same 3.6V three-cell Ni-MH format and identical connector pitch, so one battery covers the full handset lineup without modification.
  • Bench tested on actual hardware: We cycled this cell through full charge and discharge on a PMP3860 handset. The BMS accepted the pack without error, and charge termination triggered correctly at peak voltage delta.
  • First-charge cycle on Ni-MH cordless packs: After installing, seat the handset in the base for a continuous 16-hour charge before first use. Ni-MH cells shipped from storage need this slow initial charge to reach rated capacity — cutting it short leaves you with noticeably shorter talk time from day one.

Base station showing a charging error on a new Ni-MH pack

Casio DECT bases use a voltage-sensing circuit to confirm a valid battery is present before starting a charge cycle. A Ni-MH cell that has sat in storage for months can drop below the 3.0V threshold that triggers acceptance. When that happens, the base flashes an error light or simply shows no charge indicator. Place the handset in the base for 30 minutes — most bases will attempt a trickle pre-charge that brings the cell back above the acceptance voltage, after which normal charging resumes.

Handset loses pairing with the base after battery removal

Some Casio DECT handsets store pairing data in volatile memory that clears the moment battery power is removed. Swapping the battery can leave the handset unregistered, even if it was paired before. To fix this, locate the registration button on the base — usually labelled FIND or REG — hold it for five seconds, then follow the handset menu to re-register. The process takes under two minutes and restores full call functionality.

Compatible Models

PM38BAT PMP3815 PMP3850-PLUGIN PMP3860 PMP3875 PMP-3815 PMP-3860 PMP-3875

Technical Specifications

Voltage3.6V
Amp Hours700mAh
Capacity700mAh
Rate2.52Wh
Net Weight36g /1.27 oz
Gross Weight61g /2.15 oz
Approximate Weight61g /2.15 oz
Dimension 45.60 x 31.30 x 10.60mm

Product Highlights

  • Brand: Casio
  • 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 Casio handset talk time is still short after a week — is the new battery faulty?

Ni-MH cells in cordless phones typically need three to five full charge and discharge cycles before they reach rated capacity. During this conditioning period, talk time will be noticeably shorter than expected — this is normal cell behaviour, not a fault. Run the handset down until it signals low battery, then return it to the base for a full charge each time. By cycle five, capacity should stabilise at the rated 700mAh.

The handset shows full charge all night in the base but drains completely by morning — what's wrong?

This points to a standby draw issue, not a capacity fault. If the handset is not fully seated in the base cradle, the charging contacts lose connection and the handset runs off battery in standby rather than drawing from the base. Check that the handset clicks firmly into the cradle and that the charge indicator lights up on both the handset and base. A solid charge light on both units confirms the contacts are clean and aligned.

Range dropped significantly right after I fitted the new battery — why?

DECT handsets regulate transmit power based on available battery voltage. When a freshly installed Ni-MH pack hasn't completed its first full conditioning charge, its voltage sags under the RF transmit load, causing the handset to reduce output power and shrink effective range. This is not a hardware fault. Complete the 16-hour initial charge in the base, then run two full discharge and recharge cycles — voltage stability under load improves with each cycle, and range returns to normal once the cell is properly conditioned.

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