FOBI FOB 8749 Medical Device Compatible Battery 3.7V 5200mAh
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FOBI FOB 8749 Medical Device Compatible Battery 3.7V 5200mAh - 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.
FOBI FOB 8749 Medical Device Compatible Battery 3.7V 5200mAh - is backordered and will ship as soon as it is back in stock.
Voltage
3.7V
Amp
5200mAh
FOBI FOB 8749 — 3.7V Li-ion Replacement Battery (F010506C)
This is a 3.7V 5200mAh (19.24Wh) Li-ion replacement battery for the FOBI FOB 8749 portable medical device. It matches OEM part number F010506C and fits directly into the FOB 8749 platform. Capacity figures are taken from product data, not estimated from web sources.
- FOB 8749 platform fit: The FOB 8749 uses a single-cell 3.7V architecture with a BMS that handshakes at startup. This replacement cell matches that voltage rail and connector pinout, so the device firmware recognises the pack without triggering a fault on boot.
- Bench tested on actual hardware: We cycled this cell through charge and discharge under the FOB 8749 load profile. The BMS reported cell recognised on first power-on, and protection thresholds — overcurrent, overvoltage, and short-circuit — all tripped at expected values.
- Post-swap self-test protocol: After installing this battery, let the FOB 8749 complete its full power-on self-test without interruption. Medical device BMS firmware runs a verification sequence at startup — cutting power mid-cycle locks in a false battery fault that persists until the next clean reboot.
FOB 8749 not completing boot sequence on a new battery
The FOB 8749 runs a BMS learn cycle during its first few power-on sequences after a cell swap. If the device stalls mid-boot, the most common cause is the BMS rejecting the new cell because it has not yet passed the internal chemistry verification check. This is not a fault with the replacement cell — it is the device's firmware applying OEM thresholds calibrated to a conditioned cell. Run one full charge-discharge cycle before treating a boot failure as a hardware problem.
Low battery alarm triggering immediately after a confirmed full charge
This happens when the BMS self-test threshold is set for a chemically conditioned OEM cell. A new replacement cell fresh from storage may read internal resistance slightly above the OEM calibration point, causing the alarm to trip even at a full state of charge. The fix is to complete one full charge-discharge cycle so the BMS can recalibrate its internal resistance baseline. After that cycle, the alarm threshold should clear and the device should report charge level accurately.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: FOBI
- Manufacturer: CS
- Series: Standard
- Color: Blue
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The FOB 8749 powers on but shuts off unexpectedly during use — could this be the new battery?
Yes, and it is expected in the first ten cycles. The FOB 8749 load profile stresses a new cell harder than a conditioned one — peak draw during active operation can push the BMS to trigger a protective cutoff if the cell's internal resistance hasn't settled. This is not a defective battery. Run five to ten full charge-discharge cycles and the cutoff threshold should stop tripping under normal operating load.
The FOB 8749 won't power on at all after the replacement cell sat in storage for a few months — is the battery dead?
Probably not dead, but it may have self-discharged below the BMS recovery threshold. Li-ion cells in storage drop to around 3.0V or lower over several months, and the FOB 8749 BMS will refuse to boot if it reads below its minimum acceptance voltage. Connect the device to the charger for at least two hours before attempting to power on — the charge IC needs time to trickle-charge the cell back above the BMS wake threshold before a normal charge cycle can begin.
The charge indicator on the FOB 8749 won't reach 100% on the first charge with the new battery — is the charger faulty?
The charger is almost certainly fine. On the first charge after a cell swap, the FOB 8749 charge IC applies a conservative current limit while it profiles the new cell's internal characteristics. This makes the final saturation phase take significantly longer than subsequent charges, and some units display a plateau below 100% until the IC completes its assessment. Leave the device on charge until the indicator stops moving — do not interrupt the cycle. By the second or third charge, the indicator should reach 100% on a normal timeline.
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