Hi Tien
I think the battery (lipo) is just going flat. 240mA out of the solar panel is not very much. It would eventually charge the battery but with the UNO connected the solar panel has to supply enough current to operate it AND charge the battery. Don’t forget the battery will have to be fully charged while the sun is out as the battery has to run the UNO while there is no sun.
240mA would be struggling to operate the UNO without charging the battery at the same time.
Cheers Bob
Hello Robert,
How big the solar panel you reckon should i use? Thanks
Hi Tien
Depends on how much current the load requires.
I would suggest you have a detailed read of the product Wiki here
before you go much further.
Cheers Bob
Yeah. DFRobot tech Support also suggested me to increase the capacity of my solar panel. Just not too sure what the max mAh is available out there with 4.5v to 6v? Don’t want to fry the board!
Hopefully someone has tried before with a solar panel that works well with a lipo using this board.
Shall check out jaycar and altronics this weekend.
Thanks
Hi Tien
It has been a while since I have seen anything on that Sunflower device but I seem to remember there is a Max allowable solar voltage input. You should get that figure from that Wiki. I have an idea the Jaycar and Altronics units will be about nominal 12V (which probably have an open circuit voltage of about 17V) and are targeted to car/caravan use.
Have a look at this Core video for some ideas
How to Build a Solar Powered Raspberry Pi 4 With PiJuice
Cheers Bob
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Hey, I’m looking at getting some of the DF Robot Sunflower: Solar Power Manager 5Vs. Could I use this to charge a 3.7V, 5000mAh Li battery via the screw terminals?
Yes.
The Sunflower has a CN3065 LiPo charger chip.
Note: this chip has a maximum input of 6V so the solar panel must not exceed this voltage.
As @Robert93820 said the solar panels from Jaycar and Altronics are much higher voltages and would destroy the sunflower charger chip.
Cheers
Jim
Hi, does the solar power manager support load sharing?
Is there anything done to prevent the Li ion battery from being constantly trickle-charged by solar? (a known issue when using TP4056 to solar-charge 18650). How is this product better than DIY solution to using TP4056?
That’s a lot of deep questions
I don’t know about load sharing, but the user experience of this device seems to be pretty seamless which implies it handles load sharing gracefully enough.
This will likely be no different if it uses the same BMS chip.
It’s premade and ready to use 
If you have specific needs a custom solution will always be better, but i define ‘better’ here as low-fuss and ready to go.
Hi Michael,
Thanks so much for finding the time to reply.
Since I posted my question, I found the following statement on the product page (Solar_Power_Manager_5V_SKU__DFR0559-DFRobot) :
“Automatic recharge: If the battery is fully charged (DONE ON), the module input source (SOLAR IN) not powered off and the battery voltage decreases due to self-discharge or load, when the battery voltage drops below 4.05V, a new charging cycle will automatically begin.”
So I guess that this circuit is indeed causing trickle charge?
I interpret ‘trickle charging’ to mean constant, low-current charging.
The above spec reads to me as if there is actually voltage-dependent charging - the charging is only active once the cell voltage drops below 4.05V.
Which makes sense, from a battery longevity point of view.
Awesome. That’s what I was hoping for 
Although, I am not sure how they achieved that if the board is using the same BMS…
In any case, I do agree that this is a plug and play solution for most people.
Thanks again for the response!
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The Product/ site Sunflower: Solar Power Manager 5V | Buy in Australia | DFR0559 | DFRobot | Core Electronics
Has a broken link to the Product Wiki,
It should be:
The Prouduct/ Site:
Its More Documents link should be:
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Hey @Elliott254134,
Thanks for picking on that! I have passed this on to our team and we will update those links soon.
All the best.
Sam 
