I have a project in mind where I replace the tinny 40mAh LiPO battery of a "smart band" (Like a Mi Band 1) and replace it with a regular 18650 LiPo battery, so it last a long time without recharging. That would be simple, but what about if I have two of them?

My plan is to wire the battery to a TC4056A 1A battery charging board, and the loads in parallel.

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I've been told by a friend that that's fine, but I have absolutely zero formal training in electrical engineering and I'm unsure about what I'm doing... that's where I ask you. :)

Also, would you change something to make the circuit better and/or safer?

Any help is appreciated. Thanks!

  • \$\begingroup\$ Yes, that should be fine. \$\endgroup\$ – pjc50 Sep 16 '19 at 13:50
  • \$\begingroup\$ I was afraid if by connecting the devices like that they would draw 1,85V... but that would be if I connected them in series, right? \$\endgroup\$ – Deses Sep 16 '19 at 14:03
  • \$\begingroup\$ The devices don't "draw" voltage, they draw current. If you connect two loads in parallel they draw twice as much current as a single load would do. The voltage remains the same as it's a characteristic of the battery. You attempt probably is fine, but you might want to look at the current draw of your loads. \$\endgroup\$ – Sim Son Sep 16 '19 at 17:18

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