- Wed Apr 22, 2015 3:29 pm
#181440
I'm a beginner putting together a solar system to charge a single 18650 battery. I have a nominal 18V panel that claims to produce 9.5W. I'd like to increase the charge current on the Sunny Buddy to take advantage of the available power. I'm not sure what the actual losses will be, but I'm hoping that in full sun I'll be able to charge with 2A at 4V (8W). Since I'm using protected 3600 mAh batteries, I think this should be a safe bulk charging current.
Since the LT3652 has a 2A spec, I thought I'd be able to accomplish this by simply adding an appropriate parallel resistor at R_SEN, but now I'm not sure. One of the comments on the sales page mentions "You may find that at 900mA your power inductor starts to saturate. That’s dangerously close to the 1.05A spec limit of the part". Is this referring to the "68 µH L1" on the schematic that is labelled "683C" on the board?
If so, I think that's this one (http://www.coilcraft.com/pdfs/dt1608c.pdf), but it's listed there as having a 0.29A current rating, which seems too low. Does "dangerously" in the quote mean "go up in flames" or "might not provide full current"? What would I need to do to modify a 12885 Sunny Buddy v1.3 to provide a safe 2A charging current? Thanks!
Since the LT3652 has a 2A spec, I thought I'd be able to accomplish this by simply adding an appropriate parallel resistor at R_SEN, but now I'm not sure. One of the comments on the sales page mentions "You may find that at 900mA your power inductor starts to saturate. That’s dangerously close to the 1.05A spec limit of the part". Is this referring to the "68 µH L1" on the schematic that is labelled "683C" on the board?
If so, I think that's this one (http://www.coilcraft.com/pdfs/dt1608c.pdf), but it's listed there as having a 0.29A current rating, which seems too low. Does "dangerously" in the quote mean "go up in flames" or "might not provide full current"? What would I need to do to modify a 12885 Sunny Buddy v1.3 to provide a safe 2A charging current? Thanks!