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Like the title says, can I do this? I got two schematics in mind about how to wire these up, which one is the correct one?

This one is straightforward, but will it actually work if connected to load? Schematic 1, Straightforward

I think this one will interfere with the MPPT of CN3722, but I am not sure Schematic 2, With Diodes

The CN3722 and XL4015 in the schematics are in module form not bare ic, but these are the datasheets:

http://www.consonance-elec.com/pdf/datasheet/DSE-CN3722.pdf https://www.elecrow.com/download/XL4015_datasheet.pdf

user3102569
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1 Answers1

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Bypassing an MPPT controller with a diode is not a good idea, because when the diode is conducting current, it will create problems for the MPPT controller and it's power calculation.

It would be better to have a separate MPPT and BMS

The other problem is the DC/DC converter's doesn't have a cutoff, and stops at 4V so the cells will be overdrawn (and die) if there isn't any logic to shut the DC DC converter off.

Voltage Spike
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  • The Li-ions are in 3S so it has the range of 12.6v when full and 9v when empty. Also you are right I forgot the BMS there. – user3102569 Jan 21 '21 at 18:21
  • This is a bit old, so sorry for reviving an old thead. From this answer, it is not clear to me is the first circuit the OP presented is valid. I would like to mount something similar, but after thinking a bit about the first circuit, I think it would be charging/discharging the battery constantly, even when the solar panel can provide power for the load, as the CN3722 will cut when the battery is charged, and therefore there will be no flow from the solar panel to the load, no? How should we add a load to the CN3722? – jjcasmar Jul 27 '23 at 19:14