About this replacement
Burton UV604 LED — 3.7V Li-ion Replacement Battery (4000428)
This is a 3.7V, 3400mAh lithium-ion battery for the Burton UV604 LED electronic magnifier. It replaces OEM part numbers 4000428 and 60000412. The UV604 LED is a handheld magnifier used for reading, jewellery inspection, and detailed visual work where consistent backlight power matters.
- UV604 LED fitment: The UV604 LED uses a single-cell 3.7V Li-ion pack with a BMS that monitors both backlight draw and cutoff voltage. Cell voltage, connector pitch, and BMS handshake all need to match — this battery meets all three.
- Bench tested on actual hardware: We cycled this battery through the UV604 LED's charge circuit and ran the LED backlight at full brightness. The BMS held the cutoff threshold correctly and the charge indicator behaved as expected throughout the cycle.
- First-cycle brightness setting: Run the device at 50% screen brightness during the first full charge cycle. High brightness pulls extra current from a freshly installed cell and can cause the battery indicator to read inaccurately until the BMS calibrates to the new cell's capacity curve.
Why the UV604 LED screen flickers on a new battery at maximum brightness
The UV604 LED backlight is the dominant current draw in the device. At maximum brightness, the backlight pulls enough current to create a voltage sag at the cell terminals — even on a fully charged cell. If the BMS sees the terminal voltage dip below its sag threshold during that draw spike, it briefly cuts output and the screen flickers. This is not a faulty battery. Dropping brightness one or two steps eliminates the sag event and stabilises the display.
Image colour shifting before the battery indicator shows low
The UV604 LED's display driver is voltage-sensitive. As cell voltage drops through the 3.5–3.6V range, the backlight dims and colour temperature shifts before the battery indicator triggers its low warning. This happens because the low-battery threshold is set conservatively to protect the cell, but the display shows the effect of voltage drop earlier. If colours look warm or the image looks dim and the indicator still shows charge remaining, the cell is approaching its lower discharge curve. Charge the device when colour shift first appears — do not wait for the low-battery alert.