Hi,
I have an 18V 9W solar panel and LiPo 10000mAh battery. I’m looking to max out the charging rate of the Sunny Buddy. If I want 2A it’s a 0.05ohm resistor correct? What would the wattage need to be? They seem a bit hard to find, any ideas on sourcing?
In the reviews someone wrote:
"This part was used in a company project in Cheyenne, Wyoming. For the month prior to its installation, we’d been having trouble with power outages of the project, a solar-driven sensor, and finally a decision was made to massively boost the power supply by a factor of 10x to provide enough electricity. However, that meant using solar panels with a nominal voltage of 25 volts and a maximum current of 6 amps.
The datasheet on the driving chip mentioned a max input voltage of 40V and a nominal input voltage of no more than 32, so all good there. It also mentioned that the charger only allowed switching current until the voltage on the SENSE pin was reached. I’d soldered a 0.075 9W resistor into R_SEN, limiting its current output to a max of 4.5454 amps (exceeding the output current) and proceeded with the assumption that the IC would automatically limit its output current even if it could produce more.
I was correct. Though the current output reached the inductor’s saturation levels and thus stopped it behaving like a true inductor, the Sunny Buddy caught the passed-through voltage and cut off the power supply (thus preventing the 25 volts from hurting anything on the output side). It’s exceeded my expectations in performing and, to give all those out there an idea of how robust it is, is currently connected to a 100W solar panel display and a 6600mAh battery (along with the load).
So long as you don’t exceed the maximum recommended voltage input don’t worry about the current drawn; the Sunny Buddy automatically limits that. It’s much better than the current Adafruit solar charger and will be my go-to from here on out."
Is it okay to use this 0.075ohm 9W method in my case? If so, again, ideas on sourcing?
Thanks!