IBM ThinkPad T61 Replacement Battery 10.8V 4400mAh
This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.
WECARE5
Check that your old battery model number and device model to match our description. This makes sure they work together.
We ship your order same day if you buy it before 4 PM EST.
IBM ThinkPad T61 Replacement Battery 10.8V 4400mAh - is backordered and will ship as soon as it is back in stock.
Let customers speak for us
Send Your Battery Photo
Expert Technician Help
Snap a photo or video of your battery and send it to us. We'll identify the exact replacement—fast and hassle-free. Our team has helped thousands of customers find the right battery quickly and easily.
POST YOUR BATTERY IMAGE
Product & Solutions Expert
✉ sales@batteryweb.com
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
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
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
⚠️ 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.
IBM ThinkPad T61 Replacement Battery 10.8V 4400mAh - is backordered and will ship as soon as it is back in stock.
Voltage
10.8V
Amp
4400mAh
IBM ThinkPad T61 7659 / T400 2764 — 10.8V Li-ion Replacement Battery (ASM 42T5265)
This is a 10.8V, 4400mAh (47.52Wh) Li-ion battery for the IBM ThinkPad T61 and T400 series laptops. It fits the ThinkPad T61 7659, T61 6480, T400 2764, R400, and over 60 additional ThinkPad variants sharing the same battery slot and connector. Voltage and connector match the OEM spec — no modifications needed.
- ThinkPad T61 and T400 platform fit: These models share a common battery bay, connector pinout, and BMS handshake protocol across the 42T4xxx and 42T5xxx OEM part families. One cell works across the full range because Lenovo kept the voltage rail and SMBus communication spec consistent throughout this ThinkPad generation.
- Bench tested on actual hardware: We ran this cell on a ThinkPad T400 and monitored SMBus data through the charge cycle. The BMS communicated correctly with the EC, charge current tapered normally at full capacity, and the cell reported accurate state-of-charge data back to the firmware throughout.
- BIOS learn cycle after install: After fitting this battery, run the laptop down to hibernate cutoff on battery alone, then charge uninterrupted to 100% without using the machine. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap — the warning is normal and goes away after one full calibration pass.
Why the ThinkPad T61 reports a replacement battery as "poor health" in Power Manager
ThinkPad Power Manager reads battery health from EEPROM data embedded in the battery's BMS chip. A new cell ships with factory EEPROM values that don't match the charge history the laptop expects to see, so the software flags it as degraded. This is a firmware comparison mismatch, not a cell fault. One full discharge-to-hibernate followed by an uninterrupted charge to 100% writes a new baseline to the BIOS and clears the warning. After two or three full cycles, Power Manager will report health accurately.
ThinkPad shutting down at 20–30% battery remaining shown on screen
The fuel gauge IC estimates remaining charge based on voltage curves calibrated to the original cell's chemistry profile. When a new cell is installed, that profile is mismatched until the IC runs calibration cycles against the actual cell. Under full CPU and display load, the real cell voltage drops below the cutoff threshold before the displayed percentage reaches zero — the laptop shuts down to protect the cell. To fix this, run two full discharge-to-hibernate and full-recharge cycles without interrupting the charge. After calibration, the shutdown threshold and the displayed percentage will align to within a few percent at 10.8V nominal.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: IBM
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
ThinkPad Power Manager is showing my new battery as "0% health" — is the cell dead already?
No — this is an EEPROM mismatch, not a failed cell. The BMS chip on a new battery ships with factory data that ThinkPad Power Manager reads as a degraded charge history. Run the laptop down to hibernate on battery alone, then charge it uninterrupted to 100%. That single learn cycle writes a fresh baseline to the BIOS and clears the false health flag.
My T61 shuts off suddenly when the gauge still shows 25% left — what's happening?
The fuel gauge IC hasn't calibrated its voltage curve against the new cell yet. Under combined CPU and display load, the actual cell voltage hits the EC's cutoff floor before the displayed percentage catches up — so the laptop cuts power while the screen still shows charge remaining. Run two full discharge-to-hibernate cycles followed by uninterrupted charges to 100%. After that, the gauge and the real cutoff voltage will track together correctly near 10.8V nominal.
System info shows this battery as 47Wh but my old one showed 56Wh — is that wrong?
The Wh figure in system info is pulled from the EEPROM on the BMS chip, which stores the rated capacity at manufacture. This replacement is a 47.52Wh cell — that is the correct rated value for this part. If your previous battery showed a higher Wh figure, it was either a higher-capacity 6-cell variant or the EEPROM had been rewritten by a prior firmware update. Check the label on the old cell: if it also reads 47.52Wh, the figures match and the new cell is correct.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
Related Products
Engineered for Performance. Built to Last.
Check out our top-rated selection of reliable products built to last. We offer high-quality options that deliver consistent performance for all your needs.
-
Sold outUp to 19% offBatteryWeb
IBM ThinkPad 390 Replacement Battery 11.1V 6600mAh 02K6610
0.4 lb
Sale priceFrom $66.99 USD Regular price $82.99Unit price -
Sold outUp to 19% offBatteryWeb
IBM ThinkPad 240z Replacement Battery 11.1V 3400mAh FRU 02K6606
0.22 lb
Sale priceFrom $70.99 USD Regular price $87.99Unit price -
Up to 19% offNew arrival
BatteryWeb
IBM ThinkPad R60 10.8V Replacement Battery 40Y6797 4400mAh
0.99 lb
Sale priceFrom $49.99 USD Regular price $61.99Unit priceIn stock (63 units) -
-
Up to 19% offNew arrival
BatteryWeb
IBM ThinkPad R60 Compatible Battery 10.8V 6600mAh 40Y6799
1.35 lb
Sale priceFrom $81.99 USD Regular price $100.99Unit priceIn stock (21 units) -
-
Sold outUp to 19% offBatteryWeb
Sony VAIO PCG-GRX1P Replacement Battery 14.8V 2600mAh Li-ion
0.31 lb
Sale priceFrom $58.99 USD Regular price $72.99Unit price -
Up to 20% offNew arrival
BatteryWeb
Sony VAIO PCG-TR1AP 11.1V Replacement Battery PCGA-BP2T
0.68 lb
Sale priceFrom $50.99 USD Regular price $62.99Unit priceIn stock (33 units) -
-
Sold outUp to 20% offBatteryWeb
Sony VAIO VGN-U50 Replacement Battery 11.1V 2100mAh
0.31 lb
Sale priceFrom $60.99 USD Regular price $75.99Unit price
