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I have an Asus Zenpower power bank and originally I had an idea where I was going to connect a solar panel which had voltage regulator to 5volts to the charging input of the power bank but when I was testing it out I found out that the powerbank stops giving output when it's charging.

My question is can I disassemble the power bank and solder the output leads of the solar panel directly to the batteries?

The batteries are 3.6v 10050mah connected in parallel, there will be a raspberry pi connected to the output so the batteries might never be fully charged.

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    \$\begingroup\$ No, you can't safely bypass the charging circuit in your bank. If you could, that circuit wouldn't be there in the first place. \$\endgroup\$ – Dmitry Grigoryev Apr 19 '17 at 14:28
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can I disassemble the power bank and solder the output leads of the solar panel directly to the batteries?

Yes you can. But you should be aware that if you charge the cells to above 4.2 V you will destroy them, with a risk of fire and/or explosion, which might pose a hazard to your health, and to the integrity of any nearby buildings or equipment.

If the output current of the solar panel exceeds the charging rate of the cells, that might also damage the cells. Same risks as above.

Also, when it's dark the solar panel might allow the current to travel in reverse, draining the cells down below their minimum voltage (which will be somewhere between 2.5 V and 3.2 V depending on the particular chemistry). This will also damage the cells, same risks as above.

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  • \$\begingroup\$ Since they are connected in parallel does the voltage split in half? In the power bank i think there are two 3.6v batteries \$\endgroup\$ – Matthew Xuereb Apr 19 '17 at 13:46
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    \$\begingroup\$ No, in a parallel setup it is the current that splits (roughly) in half. en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws \$\endgroup\$ – Dampmaskin Apr 19 '17 at 13:47
  • \$\begingroup\$ Thank you for the information, any ideas how I can charge the power bank with the solar while still using it?# \$\endgroup\$ – Matthew Xuereb Apr 19 '17 at 13:50
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    \$\begingroup\$ Not with your current equipment. You might want to google for lithium-ion charging circuits, and try to find a suitable one with the necessary protection features, that you can connect between your solar panel and the cells. \$\endgroup\$ – Dampmaskin Apr 19 '17 at 13:54

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