This video provides a detailed teardown and programming guide for a small, inexpensive JX4615N-A3 battery voltage meter with an integrated bar graph display. The presenter begins by showing his current sodium-ion battery power supply and highlights a minor physical defect on one of his meters. He then proceeds to demonstrate how to operate and program the device, including setting different battery types (lithium, lead-acid, lithium iron phosphate) and defining custom voltage ranges. A teardown reveals the internal components, including a compact microcontroller, multiplexed LEDs for the numerical and bar graph displays, and notes the absence of individual current-limiting resistors for the LEDs. The video also touches on features like adjustable display timeout and a hidden calibration option, concluding on the device's utility as a cheap and simple battery monitoring tool.
Summarizing the Battery Voltage Meter (JX4615N-A3): Disassembly and Programming
0:00 Introduction to the Device: The video introduces a small, inexpensive battery voltage meter (JX4615N-A3) which the presenter uses with his sodium-ion cell power supply.
0:33 Physical Observation: One of the presenter's meters has a detached push-button, highlighting a minor manufacturing vulnerability related to hot glue application.
1:43 Basic Operation: The device features a push-button to activate its display, showing both a numerical voltage reading and a 5-segment LED bar graph.
1:54 LED Characteristics: The first LED in the bar graph can display dual colors (red/green) and appears dimmer, while the other four are fixed green. The bar graph is considered somewhat redundant given the precise numerical voltage display.
2:27 Programming Functionality: The main purpose of programming the device is to set the battery type (e.g., Lithium Ternary, Lithium Iron Phosphate, Lead Acid) or a user-configurable profile, which influences how the bar graph represents the battery's charge level.
Single Press: Cycles through battery types (L for Lithium Ternary, F for Lithium Iron Phosphate, P for Lead Acid).
Long Press: Enters edit mode for the selected field (e.g., number of cells for pre-defined types or voltage digits for user-defined).
6:28 User-Defined Voltage Range: The presenter demonstrates setting a custom low (8V) and high (12V) voltage for the bar graph, noting that the bar graph's linearity based on these settings seems questionable.
8:43 Adjustable Display Timeout: The backlight can be set to turn off after 0 (always on), 10, 20, 30, 40, 50, or 60 seconds. The presenter also highlights a common pitfall where incorrect programming sequence can make it difficult to exit the menu.
9:57 Power-Up Indication: Upon power-up, the device briefly displays "8 volts" with a red LED, signaling that it is configured to a user-defined voltage curve.
11:07 Model Variations: The presenter shows different variants of the device, some lacking the numerical display, but focuses on the JX4615N-A3 for the teardown.
12:09 Teardown Process: The plastic top layer of the device is carefully peeled off, revealing the internal circuit board and a plastic frame with light separators to prevent LED bleed.
14:46 Multiplexed LEDs: Observation of flickering LEDs confirms that they are multiplexed to conserve microcontroller pins.
15:58 Internal Components: The teardown reveals a very small "PUYA" microcontroller chip and a 3.3V regulator. Notably, there are no individual current-limiting resistors for the LEDs, suggesting a shared resistor or internal current limiting within the chip.
18:06 Hidden Calibration Option: The device includes a "CAL" option in its programming menu, suggesting a way to calibrate the voltage readings, though the presenter advises caution as he has not attempted it.
19:12 Conclusion & Availability: The device is inexpensive (around $2) and proves useful for quick checks of overall battery pack voltage, making it an interesting and practical component. It is expected to be available for purchase via a link in the video description.