Seeking Advice

[DavidH92]

Hi there guys, I hope you're well and thank you for your time reading and responding to this post.

I am just a dabbler, but as an ex electrician I thoroughly enjoy this new (to me) world of electronics.

I am trying to put together a rechargable power supply for some basic smart glasses,
My plan was to wire two 3.7v Li-Po in series for a 7.4v supply (my main circuit board is a 5v Nano board)

I already own some 5v lithium 1A TP4056 charging circuit boards. Micro USB input which provide 4.2V overvoltage protection

If I have a 7.4v 2S LI-PO, what can I use to recharge these batteries?

 

[rjenkinsgb]

Hi,
charging lithium cells in series gets complicated, as they must have a balance controller and over/under voltage protection system.

I'd suggest using a single cell (or two in parallel) so they can charge using a board such as you have, and use a little boost regulator to provide the 5V for the MCU board - eg. something like one of these:

DC-DC 1V-5V to 5V Voltage Regulator Converter Step Up Boost Module Power r | eBay

High power conversion efficiency up to 96% save energy. Output Current: 500mA. Due to the difference between different monitors, the picture may not reflect the actual color of the item.

www.ebay.co.uk

 

[DavidH92]

Jenkins, thank you for your response,

So this is a step up module I could install between a 3.7v LiPo battery and the 5v nano controlboard? It would then step up my voltage to 5v?

 

[rjenkinsgb]

So this is a step up module I could install between a 3.7v LiPo battery and the 5v nano controlboard? It would then step up my voltage to 5v?

Yes, exactly. There are a lot of different types as it is quite a common requirement, with so many things using a lithium cell for power.

You could also get the electronic module for a "power bank" type unit, which should give you both charge and 5V step-up in a single module.

 

[DavidH92]

Thank you so much for your help!