Powering Electron with LiPo and VIN with Batteries

I want to know if I can have an Electron with the LiPo battery plugged in and in addition connected to VIN with four AA batteries? When the LiPo battery starts to draw down power would it take power from the AA batteries to charge up and then leave the AA batteries alone until the next LiPo power draw down? I am assuming I can’t harm anything based on the documentation:

VIN
The input voltage range on VIN pin is 3.9VDC to 12VDC. When powering from
the VIN pin alone, make sure that the power supply is rated at 10W (for example 5VDC at 2Amp). If the power source is unable to meet this requirement, you’ll need connect the LiPo battery as well.

Or does VIN act like batteries being plugged into the USB port and totally powering them down before drawing power from the LiPo battery?

The Electron will be located in a location where charging a LiPo battery is not an option and changing LiPo batteries is harder than replacing four AA batteries at a remote site. The location is indoors so solar is not an option.

I had this question buried in a different post with no replies. I was hoping for some feedback.

Thanks

@RWB, @ScruffR any chance you guys can give your thoughts on this idea of powering the Electron with LiPo and VIN with batteries. I highly respect your opinions.

I have reached out to the Forum Community with this Post but can not understand why no one has responded from the Particle staff to you guys. What is wrong with the question?

I’d say the community hasn’t answered because it’s a border case not many got an opinion about. And Particle is just not as much around in this forum as some of the Elites are (too much :blush:)
I have thought about your proposal but haven’t really come up with a “reliable” answer.
My gut feeling is just a bit funny about this, but can’t prove any (also because I’d need longer testing to convince myself).
Without having looked into the Electron schematics and any number crunching, I just got the feeling that the AAs would get drained first till their voltage equals the one of the LiPo + 0.2V (schottky forward drop) and then both would get drained in parallel (with the risk of back feeding into the AAs if you don’t add a protective diode).
So not what you want to achieve.

But @BDub is the master of the electrons on the Electron - I’m more a bits guy in this respect :wink:

Thanks @ScruffR for your thoughtful insight. It is much appreciated.