Solar/DC battery charger with load sharing and 5V/3.3V output

hi all,

Thought i would share my latest project with you. It all started as a side project where i needed a solar charger for 18650 battery. Whatever i could find either did not have regulated 5V (or 3.3V) output, or it didnt have 18650 holder, or.... So i decided to try and make my own charger with load sharing and both 5V and 3.3V output.

I was impressed with Adafruit "bq24074" based charger and started from that, than added TI TPS63001 for 3.3V and TI TPS61090 for 5V output.

Beauty of TI bq24074 is that it behaves sort of like MPPT charger, once the input voltage from solar panel sytart to fall down it will automatically try to maintain the voltage as minimum of 4.5V while adjusting charging current to keep the voltage stable. Perfect even for small 5-6V solar panels.

I have the option to add TSR 2-2450 buck converter from Traco Power to expand the input to 36V.

Output 1: 5V 1.5A
Output2: 3.3V 0.8A

All SMD components on the board, including 3 TI IC's was hand soldered..

Hope you like it.

Thanks,
Alek

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