İ am working on a project that needs to charge itself through solar power, but İ need to charge it while using it. I am using a 3.7 v 600 mAH battery: (http://s.aliexpress.com/NJ3aMBVb). Can ı do that. If possible, are there any risks.


1 Answer 1


The solution is to power the circuit from the solar panel when that is available while simultaneously charging the battery.

Obviously you can't simultaneously charge and discharge the battery. Current is either flowing in or out - not both. Drawing power from the charging circuit at the battery terminals will confuse the charger as it will assume that all charge is going into the battery.

Ali Express is not a good source for components because you usually can't get proper datasheets for the devices. That is one of the reasons the products are cheap. The moto here is, "No datasheet - no sale".

  • \$\begingroup\$ 1. What if there is a cloud covering the sun. Because I need the device working non stop 24-7 2. You are right, I need data sheets but I am broke. +internet \$\endgroup\$
    – Fr1nge
    Commented Oct 15, 2017 at 20:39
  • \$\begingroup\$ That's a different question to the one you originally asked. Cloud situation will be the same as dusk and night time. \$\endgroup\$
    – Transistor
    Commented Oct 15, 2017 at 20:40
  • \$\begingroup\$ Hmmm İ see. What if İ power it up from the panel when there iş light and when there is none it automatically switches to battery. But will it cause a delay between the power source change and make the device restart. \$\endgroup\$
    – Fr1nge
    Commented Oct 15, 2017 at 20:43
  • \$\begingroup\$ Look at the datasheet for your chosen battery management system. You want one with no drop-out during transition from one to the other. \$\endgroup\$
    – Transistor
    Commented Oct 15, 2017 at 20:45

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