About this replacement
Jio JMR541 — 3.8V Li-ion Replacement Battery (EL-BP515761V / MFB260001)
This 3.8V, 2200mAh Li-ion battery is a direct replacement for the Jio JMR541 portable mobile hotspot. It fits the JMR541 unit and restores power to the device when the original cell has degraded or failed. Capacity is rated at 8.36Wh.
- JMR541 platform fit: The JMR541 uses a flat-profile Li-ion cell at 3.8V nominal — this replacement matches the original voltage rail, physical dimensions (64.85 × 57.15 × 5.50mm), and connector orientation so the BMS handshake initialises correctly on first boot.
- Bench tested on actual hardware: We ran this cell under combined modem and Wi-Fi load — simultaneous 4G data transmission and multiple connected clients — and the BMS held without tripping or reporting a fault state through the full discharge cycle.
- Ventilation during extended sessions: Keep the JMR541 in an open, ventilated spot during long sessions. When client devices are far from the hotspot, the cellular radio pushes maximum transmit power, generating heat that accumulates inside a pocket or bag and accelerates cell wear.
Mobile hotspot disconnecting users mid-session on a new battery
When the JMR541 is serving the maximum number of connected clients, the combined draw from the cellular modem and Wi-Fi radio spikes sharply. If the cell's internal resistance is higher than expected — even in a new battery that was stored long-term — the voltage can sag briefly below the BMS cutoff threshold, causing the unit to drop connections or restart. This is not a firmware fault. Charge the battery fully to 4.35V before the first session and allow one complete charge cycle before running the device at maximum client load.
JMR541 not powering on after sitting unused
Li-ion cells self-discharge at roughly 1–3% per month during storage. A JMR541 left unused for several months can arrive with a battery voltage below the minimum boot threshold — typically around 3.0V — and the device simply will not turn on. This is not a dead battery. Connect the unit to a charger and leave it for at least 30–45 minutes before attempting to power on; most BMS circuits include a recovery trickle mode that brings the cell back up from low-voltage sleep. If the charge LED does not activate at all, hold the power button while plugged in to force a BMS re-initialisation.