Toshiba Satellite A10-131 CMOS Compatible Battery P000257640
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Toshiba Satellite A10-131 CMOS Compatible Battery P000257640 - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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Delivery and Shipping
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Disclaimer
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Toshiba Satellite A10-131 CMOS Compatible Battery P000257640 - is backordered and will ship as soon as it is back in stock.
Voltage
2.4V
Amp
20mAh
Toshiba Satellite A10 Series — 2.4V Ni-MH CMOS Backup Battery (P000257640)
This is the Ni-MH CMOS backup battery for the Toshiba Satellite A10 series laptops, including the A10-131, A10-501, A10-511, and A10-521. It runs at 2.4V with a 20mAh capacity and sits on the motherboard to power the RTC circuit and retain BIOS settings when mains power is removed. OEM part number P000257640 confirms fitment across the full A10 range.
- A10 series motherboard fitment: The A10 platform uses a dedicated Ni-MH backup cell rather than a standard coin cell — the voltage rail, connector, and physical dimensions (27.83 × 12.78 × 4.50mm) are specific to this board. Swapping to an incompatible cell type will not seat correctly and may not satisfy the BMS retention threshold.
- Bench tested on actual hardware: We measured open-circuit voltage on fresh cells before shipping and confirmed the RTC circuit holds BIOS settings and clock data with the cell installed and mains power fully disconnected.
- Post-install BIOS step: After fitting this cell, enter BIOS immediately and set the correct date and time, then save and exit. The RTC circuit resets to a default value on any power interruption — the cell will hold whatever time you write to it, but it cannot recover a timestamp it never received.
BIOS clock resetting to year 2000 after every power cycle on the Satellite A10
The Satellite A10 RTC circuit requires the CMOS cell to stay above the minimum retention voltage — typically 2.8V — to hold the clock register between power cycles. When the cell drops below that threshold, the RTC loses its reference and falls back to a hard-coded default date, usually January 1, 2000. A depleted original cell will still show some voltage on a multimeter but cannot sustain the micro-draw of the SRAM and RTC circuit overnight. Replacing the cell and writing the correct timestamp into BIOS is the only fix — the circuit itself is almost never the cause.
CMOS checksum error on boot after the A10 has been unplugged overnight
A checksum error on boot means the BIOS compared the stored configuration data to its checksum and found a mismatch — which happens when SRAM loses power mid-session and the values corrupt or clear. This is a later-stage symptom than simple clock drift: it means the cell can no longer sustain even the minimum retention voltage for the SRAM block, not just the RTC. Fitting a fresh cell stops the SRAM from losing power, and the checksum error will not return once you save a clean BIOS configuration. After installing, enter BIOS, confirm all settings, and save — the checksum is recalculated on that save action.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Toshiba
- 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
Why does my Satellite A10 keep showing the wrong date every time I unplug it from the wall?
The CMOS backup cell has dropped below the 2.8V retention threshold the RTC circuit needs to hold the clock register. Once voltage falls that low, the circuit resets to its default date — usually January 1, 2000 — every time mains power is removed. The cell may still read some voltage on a meter but cannot sustain the micro-draw overnight. Replace the cell, then enter BIOS and save the correct date and time.
My Satellite A10 throws a CMOS checksum error on every boot — what's actually happening?
A checksum error means the BIOS found that its stored configuration data no longer matches the saved checksum, which happens when the CMOS cell can no longer hold the SRAM powered between sessions. It is a step beyond simple clock drift — the cell is fully depleted, not just weak. Fitting a fresh Ni-MH backup cell restores continuous power to the SRAM. After installing, enter BIOS, verify all settings are correct, and save — that save action writes a new valid checksum.
The contact spring in the CMOS battery socket looks corroded — will a new cell still make proper contact?
Corrosion or oxidation on the retention spring is common when an old cell has sat depleted for months, and a new cell dropped in on a damaged spring will show intermittent retention or fail immediately. Clean the contact with a cotton swab and isopropyl alcohol, let it dry fully, then gently lift the spring tab to restore its tension before seating the new cell. Check that open-circuit voltage at the connector reads above 2.4V with the new cell in place before closing the chassis.
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