Incorrect battery reading

[Kilo95]

Just replaced the batteries in one of my Moteinos. I recall thinking the voltage reading on it in the Gateway wasn't accurate when I used a lipo. I switched last year to a 3xAA (can get free, barely used AA batteries).  When I replaced them today and turned it on, it came up showing 4.74v as battery voltage (dead on with my DVM). Came back a couple hours later and it shows 2.63v. That's about where the voltage reading in the Gateway resided for the last set of AAs. Any ideas?

[Felix]

Did you check the reading with a DVM or are you assuming it's the same?
Ie what else could have changed?

[Kilo95]

i checked with the DVM when i first put new batteries in it yesterday around lunch. i did not check later in the day when i noticed the 2.63v reading from the node. i'll do that today. i have noticed similar occurrences before

[Kilo95]

I just checked again. VIN to GND shows 4.64v. The gateway dashboard shows 2.63v

[Kilo95]

The VIN to GND reading of 4.64 is with a DVM

[Felix]

1) Are you sure the reading is coming from that node?
2) Do you have the code running on that node?
3) What is the circuit that measures the VBat? My boards have had a few versions, including 10k+4.7K on some older WeatherShields, 1Meg+470K, and most recent boards I've standardized to 2M+1M.
The code has to account for this resistor ratio to calculate the actual voltage, if that is wrong then of course the reading will be off as well.

[Kilo95]

i am sure it's coming from that node.

i use the same code on it that i do on my other weathershield. (dont have it handy since i'm at work)

i can look at the board when i get home and see which version it is.

[Felix]

Ok the best thing is measure the resistors, otherwise take a hi-res shot and maybe I can tell although some of these 1% resistors don't have markings or they are not the usual.