DIY Power Supply for LiFePO4 Charging

Using a Mingwei-modified power supply to charge lithium iron phosphate batteries is quite effective. However, the meter added only shows current and voltage, not charging time and capacity. These parameters are useful for comparing battery discharge tests, so I specifically created a table to record the battery's charge and discharge parameters. Without this functionality, it's very inconvenient, so a mobile meter can be made. I found that just using a meter alone wasn't effective and wiring it was also inconvenient. Therefore, we can DIY this together. The process is relatively simple.

The meter's accuracy is average. It shows 3.55V instead of 3.6V and cannot be calibrated. However, it is sufficient for recording the battery's charging time and capacity.

Below is the modified power supply used to charge a large lithium iron phosphate cell:

Wiring is simple, using two 18650 batteries in series (8.3V) to power the meter. A solid perfume box works well for this.

After closing the lid, the ventilation holes are ready-made.

Display is functioning normally.

Add a switch to turn off the meter.

If you encounter a situation during the modification where there is power here but no power outside, it could be that the spring and the contact plate are not touching. Soldering can solve this problem.

Charging in progress

Manually calculating charging time is very inconvenient.

Discharging is quite convenient. It shows the duration and capacity.