FOCUSTEC MR90Y 11.1V 65Wh laptop battery

Replacement battery for Dell Inspiron 14R, 15R, 17R

This lithium-ion battery delivers 11.1V and 65Wh capacity for compatible Dell Inspiron models. It replaces part numbers MR90Y, N121Y, G35K4, MK1R0 and YGMTN across 14, 15 and 17 inch variants. The cell chemistry reduces leakage risk and provides stable output for daily mobile use. Built-in circuit protection guards against overcharge and short circuits.

Simple swap with built-in safeguards

Installation follows the standard battery bay procedure: power off, release the latch and slide the pack into place. No tools are required beyond a small screwdriver for the bottom cover on some chassis. The most common issue is forgetting to disconnect the AC adapter before removal, which can trigger a protection lock. Align the connector carefully; forcing it damages the motherboard header.

Capacity ceiling of a 6-cell lithium-ion pack

The 65Wh rating reflects the practical limit of this form factor and voltage. Runtime scales with screen brightness, CPU load and wireless activity, so heavy workloads will drain it faster than light browsing. The pack cannot exceed its designed cell count, meaning it will not match higher-capacity 9-cell options that physically protrude. Aging cells gradually lose full-charge capacity over repeated cycles.