Dead battery every 3 days

[Wagonmaster]

2011 Transit Connect, 70,000 miles. Battery completely dead if truck not used for 3 days or more. Battery is 2 years old and healthy. Will start instantly when jump started. Nothing left on such as lights, nothing left in cig lighter. Thinking a parasitic drain of some sort. Thoughts,suggestions?

[G B L]

You need an low range  ammeter to put in series with the battery and then start pulling fuses till the draw goes away.  After the fuses then you start pulling relays.  That is a good way to start .

[zalienz]

G B L is right. You need a ammeter in series with the battery that reads millivolts (mV). Anything over 50 mV is too high. The fuse pull trick will tell you which circuit is affected, and you can go from there. Aftermarket accessories are a common cause, like  a LoJack or something like that. Good luck.

[Beta Don]

Ammeters don't read volts at all, milli or otherwise  -  If you need to read millivolts, you need a voltmeter, but for what you're troubleshooting, I think you need to read milliamps

 

Don

[G B L]

Thanks Don a good catch, as english is not my strongest skill.

The computers in the tc all require some power to matain memory.  There  is always some draw.  You need an accurate ammeter with a low enough scale to see what the actual draw is and is it enough to kill the battery.

Edited September 12, 2018 by G B L

[zalienz]

Sorry, my bad, I meant milliamps, not millivolts.

 

Thanks for catching my error, Beta Don.

Edited September 12, 2018 by zalienz