Solar charger load sharing problems

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matthewa1
 
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Joined: Sat Feb 23, 2013 10:06 pm

Solar charger load sharing problems

Post by matthewa1 »

Hi,
I'm working on a project that involves powering a DC fishtank pump that requires 1.5V and 200mA. I am using the Solar battery charging circuit with a 3.7 4000mAh Li-ion battery. At the load terminal I'm using a TSP62200 1.5V Buck converter to regulate my voltage (the datasheet says it can source 300mA). I'm having a problem with not being able to draw the proper amount of current. I've also noticed that when an input voltage is present (ie connecting with usb or solar panel) the current jumps up from 115mA to 130mA even with the battery fully charged. When I plug a regular D battery into the pump it supplies 180mA. 115-130mA is not always enough to start the pump up. I'm stumped on where to look for the issue with this circuit. Any thoughts?

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adafruit_support_bill
 
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Re: Solar charger load sharing problems

Post by adafruit_support_bill »

Post a photo of how you have everything connected.

The battery should be able to source several amps of current. USB should supply at least 500mA. The current paths for each are different. What happens if you power the buck converter directly from the battery or USB?

matthewa1
 
Posts: 2
Joined: Sat Feb 23, 2013 10:06 pm

Re: Solar charger load sharing problems

Post by matthewa1 »

Thanks for your reply. I'll send pics this evening. I've identified that there is some issue with the Buck converter. The open circuit voltage on the output is 1.5 volts when the battery is connected directly to the input. As soon as the pump is connected, the ouput voltage drops to 500mV. The current draw is even less, ~80mA.

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