Bayco XPP-5570 Replacement Battery 3.7V 3400mAh

Bayco XPP-5570 / XPR-5572 — 3.7V Li-ion Replacement Battery (5572-BATT, 5570-BATT)

This is a 3.7V 3400mAh (12.58Wh) lithium-ion replacement battery for the Bayco XPP-5570 and XPR-5572 rechargeable work lights. It slots directly into both models using the same cell format, voltage rail, and connector layout as the original. When the factory cell degrades and brightness starts stepping down before the indicator warns you, this replaces it.

• XPP-5570 and XPR-5572 compatibility: Both lights run the same 3.7V single-cell architecture with identical battery dimensions and connector pinout. One cell SKU covers both models because the driver circuit and BMS handshake requirements are shared across the XPP and XPR variants.
• Bench tested on actual hardware: We cycled this cell through charge and high-draw discharge on the XPP-5570 platform. The BMS held voltage steady through turbo-mode draw, tripped the low-voltage cutoff cleanly at the correct threshold, and accepted a full recharge without flagging a fault condition.
• Turbo-mode discharge rate: Turbo mode on the XPP-5570 pulls significantly more current than standard or low modes. Avoid leaving the light in turbo when full output is not needed — the cell depletes faster under sustained high current, and repeated deep cycles at that draw rate accelerate capacity fade over time.

Bayco XPP-5570 dimming before the battery indicator drops

The XPP-5570 driver uses brownout protection to step output down before the cell actually hits its low-voltage cutoff. This means the light dims noticeably while the indicator still shows charge remaining. It is not a fault — the driver is protecting the cell from over-discharge under load. When cell capacity has faded enough that this step-down happens early in a session, the cell itself needs replacing, not the driver. A fresh 3400mAh cell pushes this threshold back to where it belongs.

XPP-5570 not holding a full charge after sitting unused for weeks

Lithium-ion cells self-discharge during storage, and a degraded cell can drop below the BMS re-initialisation threshold if left uncharged for an extended period. When this happens the light either does not power on or shows a fault on first plug-in. Plug the light into the charger and leave it for at least two hours before attempting to power it on — most BMS circuits need a trickle-charge phase to recognise the cell and resume normal operation. If voltage does not recover above 3.0V after that period, the original cell has failed and needs replacement.