Xiaomi BN4A lithium-ion polymer battery

The BN4A is a rechargeable lithium-ion polymer (Li-Po) internal smartphone battery designed to provide stable power and long usage for compatible Xiaomi/Redmi devices.

Specifications

• <p><strong>Model Name:</strong> <strong>BN4A</strong></p><p><strong>Battery Type:</strong> <strong>Rechargeable Lithium-ion Polymer (Li-Po)</strong> — slim, lightweight, and high energy density chemistry. &nbsp;</p><p><strong>Nominal Capacity:</strong> <strong>3900 mAh</strong> typical, up to <strong>4000 mAh</strong> on some original batteries. &nbsp;</p><p><strong>Energy:</strong> Approximately <strong>15.0 – 15.4 Wh</strong>. &nbsp;</p><p><br></p><p><strong>Voltage:</strong></p><p><br></p><p> • <strong>Nominal Voltage:</strong> <strong>3.85 V</strong> — standard for modern smartphone Li-Po cells. &nbsp;</p><p> • <strong>Charge Limit Voltage:</strong> ~<strong>4.40 V</strong> (max safe charge). &nbsp;</p><p><br></p><p><strong>Chemistry:</strong> Lithium-ion Polymer (Li-Po). &nbsp;</p><p><strong>Color:</strong> Usually <strong>black</strong> (typical for replacement batteries). &nbsp;</p><p><br></p><p><strong>Protection &amp; Safety:</strong></p><p><br></p><p> • Built-in protection circuitry (over-charge, over-discharge, short-circuit protection) on many versions. &nbsp;</p><p> • Common certifications include <strong>CE, RoHS, FCC, CCC, UL</strong> (varies by seller). &nbsp;</p><p><br></p><p><strong>Charging Time:</strong> ~<strong>2–3 hours</strong> (depends on charger and phone). &nbsp;</p><p><strong>Cycle Life:</strong> Often rated for <strong>&gt;550–600+ charge cycles</strong> before significant capacity loss (varies by manufacturer). &nbsp;</p><p><strong>Approx. Weight:</strong> ~<strong>55–70 g</strong> (varies by manufacturer). &nbsp;</p><p><br></p><p>⸻</p><p><br></p><p><strong>📱 Compatibility</strong></p><p><br></p><p>Designed as a <strong>direct replacement battery</strong> for these Xiaomi/Redmi models (matching the BN4A part number):</p><p>• <strong>Xiaomi Redmi Note 7</strong></p><p>• <strong>Xiaomi Redmi Note 7 Pro</strong></p><p>• <strong>Xiaomi Redmi Note 7S</strong> (depending on specific variant) &nbsp;</p><p><br></p>