Ledlenser MH4 Replacement Battery 3.7V 800mAh 14500

Ledlenser MH4 / MH5 / iH5R / ML4 — 3.7V Li-ion Replacement Battery (14500)

This 3.7V 800mAh Li-ion cell replaces the factory 14500-format battery in the Ledlenser MH4, MH5, iH5R, and ML4 headlamps, plus four additional compatible models. It slots directly into the single-cell battery compartment and works with the headlamp's onboard charging circuit.

• MH4 / MH5 / iH5R / ML4 platform: All these headlamps share the 14500 cylindrical cell format and a 3.7V nominal voltage rail. The driver boards across this lineup are calibrated to the same charge cutoff and discharge floor, so one cell specification covers the entire group.
• Bench tested on actual hardware: We ran this cell through the MH4's charge circuit and confirmed the BMS accepted the full charge cycle without error. Discharge tests across low, mid, and turbo output modes showed stable voltage delivery until the driver stepped down at the low-voltage cutoff threshold.
• Single-cell replacement rule: The MH4 series runs one cell — but if you own multiple Ledlenser headlamps from this family, never swap a partially depleted cell from one unit into another. A cell that has already cycled 50 or more times will drain faster under turbo draw than a fresh cell, causing premature driver step-down in the receiving headlamp.

Turbo mode cutting out long before low-battery warning appears

Turbo mode on the MH4 draws significantly more current than standard or low modes — often five to ten times more. A cell with even moderate capacity loss cannot sustain the high current demand, so its terminal voltage sags below the driver's cutoff threshold before the fuel gauge registers a low state. The driver steps output down to protect itself, which looks like a sudden dimming rather than a warning. If this happens with a new cell, confirm the cell charged fully — terminal voltage at full charge should read approximately 4.2V.

Headlamp flickering or cycling through modes near end of charge

When the cell voltage drops toward the driver's brownout threshold, the driver briefly loses enough voltage to hold its current mode, resets, then tries to restart — creating a flicker or a rapid mode cycle. This is not a fault with the driver; it is the driver responding to voltage instability at the cell terminals. Switching to a lower output mode stops the cycling because the reduced current draw keeps terminal voltage above the cutoff. If a fresh, fully charged 14500 cell still causes this behaviour, check the battery contacts in the compartment for corrosion or poor spring tension.