Toshiba Dynabook R730/B Replacement Battery PA3831U-1BRS 10.8V
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Toshiba Dynabook R730/B Replacement Battery PA3831U-1BRS 10.8V - 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
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.
Toshiba Dynabook R730/B Replacement Battery PA3831U-1BRS 10.8V - is backordered and will ship as soon as it is back in stock.
Voltage
10.8V
Amp
4400mAh
Toshiba Dynabook R730/B Series — 10.8V Li-ion Replacement Battery (PA3831U-1BRS)
This is a 10.8V, 4400mAh (47.52Wh) Li-ion battery for the Toshiba Dynabook R730/B, R731, R732, R741/B, and related thin-and-light business notebooks. It replaces OEM part numbers including PA3831U-1BRS, PA3832U-1BRS, PABAS235, PABAS249, and PA5043U-1BRS, among others. Physical dimensions are 206.10 × 43.45 × 19.90mm — confirm your original battery matches before installing.
- R730/R731/R732/R741 battery platform: These Dynabook models share a common 10.8V three-cell Li-ion battery bay, connector pinout, and BMS communication protocol. Toshiba assigned multiple OEM part numbers across production runs — PA3831U through PA3931U and the PABAS series — but the electrical spec and physical form factor are the same across all of them.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Dynabook R730-series unit. The BMS handshake completed correctly, charge termination triggered at full capacity, and the thermal cutoff circuit responded normally under sustained CPU load.
- Post-install recalibration on Dynabook firmware: After installing, run one full discharge down to the hibernate cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell. Skip this step and the fuel gauge IC will keep reading from stale EEPROM data — the system will report poor health or an inaccurate charge percentage from day one.
Why the Dynabook R730 BIOS flags a new battery as poor health
Toshiba's firmware stores battery health data in EEPROM on the old cell. When you swap the battery, the BIOS reads stale cycle count and capacity data that no longer matches the new cell's chemistry profile. The result is a "poor battery condition" warning even on a brand-new cell. Running one full discharge-to-hibernate followed by an uninterrupted full charge lets the firmware write fresh calibration data to the new cell's EEPROM. After one or two cycles, the health indicator normalises.
Dynabook R730 shutting down at 20–30% charge shown
This happens when the cell can no longer sustain voltage under the combined load of CPU activity and the display backlight. As the battery discharges, voltage drops — and under full draw it crosses the BMS low-voltage cutoff threshold before the fuel gauge reaches 0%. The gauge was calibrated against the old cell's discharge curve, so the percentage shown is wrong. Run the full discharge-to-hibernate recalibration cycle. After two full cycles, the fuel gauge IC maps the new cell's actual voltage curve and the premature shutdowns stop.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Toshiba
- 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
My Dynabook R730 shows the new battery as "0% available (plugged in, charging)" and never updates — what's happening?
The fuel gauge IC is reading EEPROM data written by the old cell and hasn't yet mapped the new cell's voltage curve. This is a calibration gap, not a faulty battery. Discharge fully to the hibernate cutoff, then charge uninterrupted to 100% without putting the laptop to sleep mid-charge. After one complete cycle the percentage reading will start tracking the new cell correctly.
System information shows the wrong Wh rating for this battery — it says 43Wh but the cell is rated 47.52Wh. Is the battery faulty?
The Wh figure displayed in system info comes from the EEPROM on the battery itself, and different production runs in this OEM family — PA3831U through PABAS265 — shipped with slightly different EEPROM-rated values. The actual cell chemistry and measured capacity are what matter, not the stored Wh string. Run a full discharge-to-hibernate cycle followed by a full charge and check whether the figure updates. If it remains mismatched, open Toshiba Battery Check or a tool like HWiNFO and compare the design capacity against full charge capacity — those two values converging is the real confirmation the cell is performing correctly.
Charge stops at 80% on the Dynabook R731 and won't go higher — is this a defective cell?
This is almost always a BIOS-controlled charge limit, not a cell fault. Toshiba's ECO Charge Mode caps charging at 80% to reduce long-term cell stress when the laptop is used primarily on AC power. Open Toshiba Power Saver or Toshiba Settings and look for the battery charge mode option — switch from ECO to Normal and the charge ceiling moves back to 100%. The battery itself is functioning correctly; the firmware is doing exactly what it was configured to do.
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