I'm building a solar project to monitor charge current and discharge current as well as lipo 'State Of Charge'.

The configuration is a 5V solar panel feeding a TP4056 which B+/- connect to a MAX471 bidirectional current monitor which connects to a LiPo in parallel with a MAX17043G lipo fuel gauge.

Unfortunately in this configuration with sensors on the B+/- outputs I cannot associate my TP OUT ground pin to those sensors without creating a ground loop that would prevent TP protection from working properly. I understand this is a non-typical configuration but this is the only way I could monitor charge & discharge current with one sensor and one analog pin.

Any input would be greatly appreciated.


Module references:

enter image description here

  • 1
    \$\begingroup\$ 1) the diode between solar panel and TP4056 is the wrong way round 2) You have 6 connections on the TP4056 which I find weird, the TP4056 modules I know only have 4 connections: Pin+, Pin-, BAT+, BAT- 3) all the GND connections and battery - can be connected together, that would make a more clear schematic. \$\endgroup\$ – Bimpelrekkie May 16 at 8:21
  • \$\begingroup\$ @Bimpelrekkie Some modules DO have 6 pins - Out+ and Out- in addition to those you describe. It's certainly very confusing when people use an IC part number to describe any one of several dozen different designs of module based around that IC, none of which ever come with any documentation. \$\endgroup\$ – Finbarr May 16 at 14:19
  • \$\begingroup\$ @Bimpelrekkie This is a TP4056 with built in DW01, here is a link to some talk about them. They end up being very cheap on amazon ect. Thank you for pointing out the diode I just threw that in haven't gotten to figuring out what kind of diode nor details about voltage drop yet. \$\endgroup\$ – Christ0pher May 16 at 18:16
  • \$\begingroup\$ @Finnbarr You're right I'll update post with common boards I am using. \$\endgroup\$ – Christ0pher May 16 at 18:17
  • \$\begingroup\$ I'm fairly sure this problem solved itself... The ground path goes through the TP module from B- Through DW01 transistors to Out- so I don't need to reference the B- but just the Out-. As long as the DW01 hasn't shut power down that ground reference is still accurate. \$\endgroup\$ – Christ0pher May 18 at 16:21

The B- and Out- should not be connected under any circumstance when using the DW01 type TP4056. The B- ground reference will be connected to Out- as long as the DW01 has not disabled the Output power.


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