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Is this [dead link removed] correct?

Think of it as a power bank. The 10 V input is a solar panel.

How is the battery and solar panel connected?

The site say that when the switch is open, solar panel charges the battery. When the switch is closed, does the solar panel and battery together power the load? Is it in parallel?

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Yikes. That site is icky.

You cannot simply connect 10 V to a LiPo battery. That is a good way to get an explosion/house fire/sad battery/sad you. LiPo batteries (and several other battery chemistries) require CC/CV charging, meaning they need constant current charging up to a float voltage, and then constant voltage charging after.

Another issue is that you cannot simply connect a solar panel to the input of that circuit. Solar panels do not provide a fixed voltage (it varies with sun intensity) and operate with poor efficiency unless you put in a little extra effort to do maximum power point tracking.

It sounds like you want to build a solar-powered battery charger circuit. Luckily, there are existing solutions that make this task easy. There are many ICs that are both MPPT controllers and multi-chemistry battery chargers. For example, the Linear LT3652, which is suitable for small panels/smallish batteries (max charging current 2A). As is characteristic of Linear parts, the datasheet is quite good and provides a wealth of information on how to design for various battery chemistries and load configurations.

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  • \$\begingroup\$ So, a workaround would be charging the power bank first through the solar panel, and cut off feed from solar panel to provide load from the charged battery? \$\endgroup\$
    – Stannis
    Dec 12, 2016 at 13:17
  • \$\begingroup\$ Wouldn't the load be regulated to provide stable 5v in this circuit? \$\endgroup\$
    – Stannis
    Dec 12, 2016 at 13:29
  • \$\begingroup\$ The LT3652 can diode-OR the panel and battery to supply the load. I'm not sure what you mean by your second question, could you clarify. \$\endgroup\$
    – uint128_t
    Dec 12, 2016 at 20:44
  • \$\begingroup\$ Doesn't the 7805 provide CC/CV? The 10v and BT1 are connected in parallel, by the way. \$\endgroup\$
    – Stannis
    Dec 19, 2016 at 2:47
  • \$\begingroup\$ The 7805 is a voltage regulator, which means it provides only constant voltage. There is a reason that ICs designed specifically to charge batteries exist. \$\endgroup\$
    – uint128_t
    Feb 18, 2017 at 17:25

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