Bea-fon C70 Replacement Battery 3.7V 900mAh Li-ion
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Bea-fon C70 Replacement Battery 3.7V 900mAh Li-ion - 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.
Bea-fon C70 Replacement Battery 3.7V 900mAh Li-ion - is backordered and will ship as soon as it is back in stock.
Voltage
3.7V
Amp
900mAh
Bea-fon C70 / S400 Series — 3.7V Li-ion Replacement Battery
This 3.7V 900mAh (3.33Wh) Li-ion cell replaces the original battery in the Bea-fon C70, S400, S400 EU001B, S400 EU001W, and compatible variants. These are slim feature phones built around a compact battery bay — a flat cell measuring 53 x 34 x 4.30mm. Fit is exact; no trimming or adapter needed.
- C70 and S400 platform compatibility: Both models share the same battery bay dimensions and voltage rail. The connector orientation and BMS handshake protocol are identical across the S400 EU001B and EU001W variants, so one cell covers the full lineup without modification.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the S400 platform. The BMS accepted the cell without fault codes, protection cut-off triggered correctly at low voltage, and charge termination fired at 4.2V as expected.
- Fuel gauge recalibration on first install: After fitting this cell, let the phone discharge fully to auto-shutdown, then charge to 100% uninterrupted. This gives the fuel gauge IC one complete reference cycle against the new cell's discharge curve before normal use.
Why the Bea-fon C70 reports wrong battery percentage after a cell swap
Feature phones like the C70 use a basic fuel gauge IC that builds its capacity model from the cell it first trained on. Swap the cell and the IC is now reading an unfamiliar discharge curve against an old map. The percentage displayed reflects where the old cell would have been at that voltage — not where the new cell actually sits. One full discharge-to-shutdown followed by a complete charge cycle resets the reference points the IC uses to calculate remaining capacity.
Sudden shutdown at 20–30% on the Bea-fon S400 after replacement
This happens when the fuel gauge IC hasn't calibrated to the new cell and the phone is still using the old discharge curve to estimate state-of-charge. Under load — an active call or backlight at full brightness — the cell voltage drops faster than the stale map predicts, and the BMS cuts power before the displayed percentage reaches zero. Run one full discharge cycle to auto-shutdown without interrupting charge. After that cycle, the IC recalculates the voltage cliff point and the shutdowns stop. Target a resting voltage of 3.6–3.7V at the 20% mark to confirm calibration is tracking correctly.
Compatible Models
Technical Specifications
Product Highlights
- Brand: Bea-fon
- Manufacturer: CS
- Series: X-Longer
- Color: Black
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The Bea-fon C70 won't turn on at all after the replacement battery sat in a drawer for a few months — is it dead?
It's almost certainly a BMS lockout. If the cell discharged below 2.5V during storage, the battery management system shuts off output to prevent cell damage — the phone gets no power and won't respond to the power button. Connect the phone to a charger and leave it for 20–30 minutes without pressing anything; the charge IC trickle-charges the cell back above the BMS recovery threshold, usually around 2.9V, and the phone starts responding again.
The percentage on my Bea-fon S400 jumps around erratically — 60% one minute, 45% the next — even though I'm not using it heavily.
The fuel gauge IC is still recalibrating against the new cell's discharge curve. The old curve data stored in the IC doesn't match how this cell's voltage behaves at each state-of-charge point, so the percentage reading is unstable. Run one complete discharge to auto-shutdown, then charge to 100% without interruption. After that single reference cycle the IC locks onto the correct curve and the percentage stabilises.
The phone feels warm near the battery compartment while charging — is the new cell faulty?
A new high-impedance cell generates more heat during charging than a well-cycled cell, because the charge IC is pushing current into a cell with slightly higher internal resistance straight out of storage. This is normal for the first two or three charge cycles and settles as the cell conditions. If the warmth is uncomfortable to hold or the phone is hot — not just warm — stop charging and check that the charger output matches the rated 5V input; anything above that stresses the charge IC and cell together.
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