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Connect lipo directly to Wemos D1 Mini

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(@garnold)
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Question, I would like to connect a 3.7v lipo to a Wemos D1 Mini. I do not need the lipo charging feature so I'm looking to avoid getting the battery shield. Here is where I'm getting confused. There are the 2 pins for voltage out. These are the 3 and 5 volt pins. I've thought that I read that you can also send voltage in to these pins to power the device. Is that correct? I just don't want to burn out the Wemos if I'm wrong. Now, let's say I can send power into the Wemos via those pins. Would sending 3.7 volts into the 3 volt pin burn up the board? I'm also confused where the voltage regulator steps in a fixes the voltage if it's to high? This is a simple project and I'm trying to avoid stacking stuff and adding to many extra parts. Lastly, if I do send in power via the 3 volt pin, does this conserve power because the voltage regular is not being used?

Thank you!


   
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triform
(@triform)
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@garnold

This board has USB, correct?  If so, then the regulator may need more than 3.7v, but possibly not.  Try connecting the lipo to the 5v pin and of course ground. I know the ESP will not like a fully charged LIPO on the 3.3v rail, but going through the 5v/regulator path should be safe even if it does not work.

Scott

 


   
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byron
(@byron)
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I think the wemos has a voltage drop with its regulator that would be too large to use 3.7 volts to connect to its 5v  usb port.   And indeed you should not put 3.7 volts into its 3v pin.   You could maybe rig up a voltage divider, but my LIPO's usually start at 4v+ and then drop to 3.7 for their working period before rapidly fading away, and its important not to let the fade too far away or they will be damaged.  So it's far better and safer to use a proper LIPO battery management system.   For my projects requiring a LIPO I use one of Adafruits feather boards that has proper battery management facilities.  Actually I've just go a new ESP32 board called TinyPico which has some very good battery management and deep sleep abilities.  I've not used it yet but it looks most promising.   I like my wemos boards, but not for using them with batteries.

Just in case you do get to play around with voltage dividers circuits or voltage regulator circuits yourself the health warning of being particularly careful not to short LIPO batteries or you may find things getting rather too hot very quickly. ? 

 


   
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triform
(@triform)
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@byron @garnold

If the regulator is an LDO, then it would probably be fine with just the lipo in.  I myself am not a big fan of voltage dividers for regulation, but that's me, a diode would do the same I would think, but Taters, Tomaders 😉 In the end, I would not put unregulated power into a uC. I have "learned" my lesson several times.

I agree that the power board would be best, even if not charging. 

Scott

  

 


   
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(@garnold)
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@triform

Yeah, I just ordered the battery shield for the Wemos D1 Mini because I just don't want to mess around with this. My electronics skills are bad at best and I just want to actually use this weather tracker I have tried to get off the ground. It might be overkill, but it will work and I can have some fun with this project.


   
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triform
(@triform)
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Posted by: @byron

 Actually I've just go a new ESP32 board called TinyPico which has some very good battery management and deep sleep abilities.  I've not used it yet but it looks most promising.   I like my wemos boards, but not for using them with batteries.

Nice.  I have heard a little about these and they look like a good board. Let us know how you like it! 


   
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(@garnold)
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@triform

I'll make sure to post the completed project when done. I have a bunch of posts around here that I started to gather info to build the project and it's kind of messy HAHAHA! 

When it's completed I'll make sure to take pictures and do a write up so that I can explain why I did what I did and maybe gather some creative comments on how I can improve my next project 😉


   
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