Upgrading A Low-cost LX-2BUPS UPS Board To Repair Deadly Flaws

Low-cost uninterruptable energy provide (UPS) boards that take Li-ion cells of some description appear to have cropped up in all places the previous years. Discovering use in purposes corresponding to retaining single-board computer systems ticking alongside within the case of an influence failure, they might appear to be a panacea. Sadly most of those boards include a collection of deadly flaws, corresponding to those who [MisterHW] present in an LX-2BUPS board obtained from AliExpress. Worst of all was the deep discharge of the Li-ion cells to beneath 2 V, which took some ingenuity and arduous work to repair this and different issues.

The patched up XR2981 boost IC with MCP809 reset IC installed. (Credit: [MisterHW])
The patched up XR2981 enhance IC with MCP809 reset IC put in. (Credit score: [MisterHW])

This explicit board is rated for 5V at 3A, that includes the all too frequent TP4056 as charging IC and the XYSemi XR2981 enhance converter. Since there isn’t any off-switch or different protections on the board, the XR2981 will fortunately maintain working till round 2.6V, at a fairly astoundingly excessive idle energy consumption. Due to this the fixes principally targeting optimizing the XR2981, by utilizing higher resistor values (R7, R8, R9), in addition to including a 3.15V MCP809 reset IC, to cut back idle energy utilization of the enhance converter and disable it beneath a secure cell voltage.

The ultimate coup de grâce was the eviction of the crimson LED (D6) and changing it with the blue LED from D2, to cease the previous from draining the cell as effectively. With these adjustments in place, idly utilization dropped from almost 900 µA to simply over 200 µA, whereas stopping deep discharge. Though this board now has a second life, it does elevate the query of what the purpose of those low-cost UPS boards is that if it’s important to spend time and money on remodeling them earlier than they’re considerably acceptable. What’s your go-to answer for these boards?

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