Powering a Sparkfun pro micro project from lipo

Using Arduino Project Guidance
1

I'm getting very confused on what my options are for powering the following circuit from a lipo with onboard charging. The Sparkfun is 5v and the other chips are all good for between 3-5V.

The battery needs to provide about 650mah.

Ideally:

  • Have a single USB providing serial/charging power as it does now - nice to have.
  • Can't add or remove anything when built (e.g. physically unplugging a battery etc) - must have
  • Prefer not to have to switch between charge and run modes manually - nice to have (e.g. charge and load).
  • Keep it small!

Happy to replace the Sparkfun with a 3.3v based board, even better would be if it had some onboard storage so I could do away with the EEPROMs!

2

I've been puzzling how to convert my prototype from USB to (charged) lipo power. I just put the following together and it seems to work. That is, feed VCC into the TP4056 from the Sparkfun, charge the battery and power out back to the Sparkfun RAW.

When USB is plugged in and the battery needs to be charged, it charges. When USB isn't plugged in, the TP4056 supplies power to the Sparkfun via RAW. This is well below the Sparkfun's 5V, but it powers up and runs.

Question is, what problems will I encounter? The battery is being managed (voltage cut-off at both ends).

I'm a bit nervous because there appears to be a power loop, but I think it's fully managed?

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3

I have merged your cross-posts @stevec5 .

Cross-posting is against the Arduino forum rules. The reason is that duplicate posts can waste the time of the people trying to help. Someone might spend a lot of time investigating and writing a detailed answer on one topic, without knowing that someone else already did the same in the other topic.

Repeated cross-posting can result in a suspension from the forum.

In the future, please only create one topic for each distinct subject matter. This is basic forum etiquette, as explained in the "How to get the best out of this forum" guide. It contains a lot of other useful information. Please read it.

Thanks in advance for your cooperation.

1 Like
4

I think I have already answered it, check your other post.

5

Hi gilshultz, I can't find a response anywhere?

I posted these separately as I'm pretty sure the diagram is a terrible idea but I couldn't work out why. I now think it's because when the TP4056 decides it's worth charging the battery, it'll do so from the battery - basically just going around in a circle, wasting a little till it hits lower thresholds.

But, what's a "good" way of doing this? Just get rid of the Sparkfun VCC to TP4056 IN+ and charge from its USB?