Hello,
I was looking to add a resistor to the Rsen of the sunny buddy module found here:
https://cdn.sparkfun.com/assets/learn_t … ut_map.jpg
The resistor I was looking to add was around the 0.08 to 0.1 ohms mark since I require to charge the battery at a relatively higher current for my application. (Around 2 Amperes)
I was just wondering if there is anything I should take into account before adding this resistor in parallel with the 0.22 ohms, is this going to make my Lipo battery act volatile and cause irregularities with the internal battery chemistry?
Thank you
The IC should be able to handle it but the traces and other circuitry may not be able to. I would advise testing with lower values leading up to your desired 2A.
Will start from 0.15 ohms and decrease till 0.07 then,
Thank you very much Brandon!
TS-Brandon:
The IC should be able to handle it but the traces and other circuitry may not be able to. I would advise testing with lower values leading up to your desired 2A.
I apologize, but it seems that I have forgotten to ask about the potentiometer calibration for higher sense currents. Would i need to tweak to a different value or will keeping it at 3V suffice?
It’s possible you might have too, you would need to figure that out experimentally. It really depends on the solar panel you’re using and how much current it’s able to deliver.
TS-Chris:
It’s possible you might have too, you would need to figure that out experimentally. It really depends on the solar panel you’re using and how much current it’s able to deliver.
I am currently using a 7.4V Voc and 3.17 A Isc solar panel with a Vmp of 6.3 V. Should i be increasing or decreasing the voltage being fed into the ‘Set’ pin which leads to theVin_reg of the chip to be able to charge my battery at 2A?? If so, what should that voltage value be or how should I calculate/find it?
Also, the saturation current of the inductor is around 0.85A, should i look into sourcing an inductor of higher saturation current?
Thank you
The board just isn’t made to go much above 550mA. You’re definitely going to need a different inductor if you want 2A and may need to change other components as well. Unfortunately we can’t really support the board if you’re going to be doing those kind of modifications but feel free to post about how it goes so others can benefit from your findings.
Hello,
So I settled with using a 0.15 Ohm resistor for R_sen to ensure my charge current is at 1.11A. I did hook a ACS711 current sensor at the battery input to see how much the battery is being charged by. I have also hooked up a arduino nano coupled with a 5 V DC to DC boost converter as a load to the SunnyBuddy load. I did not however connect a resistor for I_Sen.
The arduino IDE tells me that approximately 0.11A is being supplied to my battery from my 20W solar panel (sized at 18V) and I am confused as to why it is not larger??
Have you tried measuring current with a ammeter or a DMM? It’s possible and error in your code is making it look like it’s a lot less than what is actually passing.
