If you use I= E/R on a 12 to 13.8 volt battery would you get:  
12V/160,000 Ohm = .000075 Amp draw, and  13.8V/160,000 Ohm = .00008625 Amp draw
A good battery shouldn’t show any change in that little bit of current.   Especially if you drive the car frequently..

     Thank you, I wasn’t sure how to compute that. What I have is a vehicle that after a few days in the cold weather the battery get to the point that it won’t start. Had it checked and was told I had a voltage draw that was draining the battery . Battery is less than a year old , thinking that supplier doesn’t want to honor warranty. I put my amp probe clamp on it and see around .45 amps . Do I built the monitor as described in earlier post here to monitor the voltage and didn’t want to necessarily add to the draw. 
     I have a  10,000ma power bank that will stay on to operate the ESP 8266 so it should run for days and monitor the condition of the battery. Haven’t figured out to have it send me text messages yet or take several readings a day just a constant reading. I just go to chrome and check the ip .

Hi Larry.
To send messages from the ESP32, you can use, for example, email or telegram. Or you can even send the messages via MQTT to another platform like Node-RED for example.

• https://randomnerdtutorials.com/telegram-request-esp32-esp8266-nodemcu-sensor-readings/
• https://randomnerdtutorials.com/esp32-send-email-smtp-server-arduino-ide/

Regards,
Sara

Thanks I will read up on this, already was looking at your Telegram sketch . I have written a program that  in Telegram  when given a value to print value is HIGH or Value is LOW but not actual values like 12.25 . So does it allow values or just text, thanks.

The current drain for the voltage divider is 12V / 160,000R = 0.000075 A = 0.075 mA = 75 uA.  So assume your vehicle battery is rated at 60 Ah or 60,000 mAh.  So you get 60000 / 0.075 = 800,000 hours to drain the battery by only the voltage divider.  800,000 hours = 33,333 days = 91 years to drain the battery.

Great information, thank you 

Larry, your vehicle probably has a theft alarm which will constantly draw power. I have found with a poor battery, if a vehicle is used say every 3 days, no problem noticed, but left for 3 weeks, a poor battery is severly depleted.
It might be enlighening to check the current draw on your battery when vehicle is off and locked. If that seems OK I would guess you need a new battery.

David , thanks, I have done that with an amp clamp and had something like .39 to .5 draw

I am not an expert in this area, but 500mA could be normal for an alarm system, plus anything else usually operative, ie central locking sensor, radio keycode keep alive. I would definitely suspect the battery. One way to check is to disconnect it for a week, then connect up and see if car starts.

Will do that eventually, just waiting for weather to get better, I use it to plow and also want to rule out temperatures. If it because of extreme cold , that would also be a good telltale sign of a poor battery. 

Hi.
Answering your question about telegram, you can send values and text.
But, I think the values need to be converted to text first.
Regards,
Sara

Something like an if statement, if value = then serialPrint value in text format. I  going to have to think about how to do that . I programed it to say high, low and no charge needed by reading values. Just haven’t figured out how to send the change in numbers.Thanks

Then let me know if you need any help.
Regards,
Sara