Q2 in MPPT-2420-LC

Charge Controllers
1

Hi!

I wish to know what is the purpose of Q2?

2

It’s to block reverse current from battery to solar panel during the night. See also here: https://github.com/LibreSolar/MPPT-2420-LC/issues/19

1 Like
3

This is what I was thinking about, Thanks!

I’m thinking of a special application. I might open a new topic for it later but for now I would address a second question here but it is not strictly related to Q2, hope it’s not a problem.

I had no time to deeply study the fw, I only spent time to study the schematics and documentation.

The documentation says the hw can be used as boost converter with software change, and that the feature is already tested.

Is this feature already Implemented in the fw?

I also briefly share my thoughts here. I’m thinking of a way to use this mppt charge controller for a battery charger in buck mode during day time than during night time I would use it as a boost converter to power LED’s so the energy stored in the battery will be used for lighting. (I know I do need some hw modifications as well)
If you think it is worth opening a top optic it we can do that.

4

Yes, it’s already implemented. You just need to change one line in config.h and maybe some voltage thresholds to make it a boost converter.

Your application seems to require at least one additional switch at the high-side to disconnect the solar panel and connect the LEDs. It makes sense to open a separate topic for that.

5

Thanks for that!

Yep something like that, but the solar panel still needs to be connected in a way to be able to read the voltage on it, which is needed to detect day/night conditions.
Probably Q2 also needs to be replaced by a high side switch.

I will think about and will turn back later on a separate topic.

Thanks again!