This is...was suppose to be simple project...but it has escalated into quite the beast.

In short I am trying to build a device that can sense when it moves too much from whatever it is calibrated at...which we have working...and this device will relay to a small number of other devices used as a sort of repeater to deliver a alert to an app. All that is working...but we are having issues charging. Let me elaborate.

Someone suggested I use a ball bearing switch to keep the charging port disabled while outdoors, to prevent a short. This works to a point. When I turn it upside down it does indeed allow that port to become active and allows charging but it also turns on the device bypassing the power button...which of course causes the alarm to go nuts. Plus the added draw of the MPU, Buck to Piezo, and Feather makes the charge take forever...

What I would like to do is keep the charge port inactive(no voltage) until voltage is applied and when it is applied the MC(feather 32 by adafruit) is turned off. I believe turning off everything via pulling to ground the EN pin will work...but how do I keep voltage off the charge port when not connected?


In short, any ideas on how to keep disabled the charge port when no voltage is present, then disabled everything when voltage is?

 

How about having a relay connected to the charge port instead of that tilt switch? If there's no voltage on the port, the relay isn't operated, and the port isn't connected to any internal electronics. Then you plug the unit in (or do whatever's needed to apply power) and the relay operates, and connects the voltage to the charging circuit, while simultaneously disabling all the other electronics. It seems that would do the job.

 

A person on another forum(yes I posted this request to 4 different ones in hopes of compiling best method or at least having options)...suggested that I move my switch in the below drawing from the Lipo lead to the EN pin...which also gets rid of the one transistor...but I will likely still have a 2.8ish Voltage on the DC charge port that goes into the USB when the unit is on...I am still looking for a possible answer to that.

Here is a rough...cough...sketch/scribble of what I am talking about...

 

Okay, so 1st major issue has been resolved. Using switch for enable EN pin instead of the battery positive fixed the odd issue of it turning on when charging.

Now my last question.
Is it going to be possible for me to completely stop flow of voltage out the DC charge port when not plugged in? In other words I want something to stop the voltage before it reaches the charge port. I tried a transistor as previously mentioned which actually worked perfectly to stop that voltage I mentioned, but it also created some heat, and would likely not last long, also when charging over 1.8 volts was missing from the output...meaning there was not enough to charge properly. Now I am thinking a Diode of some sort. This device uses a standard 2.1 Amp/5V charger, and I am using a IN5819 which sort of works...it is letting more of the voltage through when charging but the charging port still has about 2V on it. should I double them up?

 

I've told you, use a relay.

 

Oh, I see that suggestion now. Sorry. Missed it. However I do not have a low voltage relay...I have some appliance relays. Any other possibilities? I have lots of different mosfets, transistors, diodes, etc...