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opensolarproject / OSPController

ESP32 Smart Solar Charger - the Open Solar Project
https://github.com/opensolarproject/OSPController/wiki
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Different panel voltage #6

Closed 03K closed 4 years ago

03K commented 4 years ago

I have all the parts ready for solderong :) However, my input voltage is 48V. I will drop down to 42V in order to mainly charge electric skateboards :) Can you point out where I need to tweak your setup in order to work with approx. 48V. I see the voltage divider must be different, I am thinking to put small dc-dc converter there too so I can adjust if I change my panels condiguration. Cirrently its 4 panels in series. Do I need to modify the software?

austrisv commented 4 years ago

if you need a different output voltage - you can set it from drok side or via serial/curl interface (outvolt). Though my understanding is that for charging you don't need to do it. As you will connect the skateboard/battery - the voltage will 'automagically' drop to the batteries level. And esp32 will keep track of current (ampers) delivered to the battery. At least that was my observation (which I also described/asked to confirm in a question https://github.com/opensolarproject/OSPController/issues/12)

t413 commented 4 years ago

Hey @03K, it was great chatting with you on the discord chat and getting you ready to build when you're back home with your gear.

For anyone else wondering: @03K has 4x 13Vdisconnected = 52V max. Sounds like The Vmppt of his panels together may be ~48V. This is pretty nonstandard, usually panels are sold with a nominal voltage of 12, 18, 20, or 24V. See the table on this page for more. The goal is to make sure your VMP - typical (that's the approximate voltage at maximum-power-point typically) is above your max battery voltage. That's because we're using a buck converter that can only regulate voltage down.

The DROK regulator we're using can take an open-voltage of ~80V (mine is 82V and works fine) so it's almost always better to get another panel in series to have a higher input voltage.