Bluetooth ODBII dongle question

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QueBert

Lifer
Jan 6, 2002
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I started using mine again today, I have Torque on my phone set up to monitor and display all sorts of useless shit. Any ways, when I exit Torque it displays a reminder for me to unplug the dongle. I Googled this and didn't really find anything helpful. I know when my cars off the lights on the dongle blinks randomly, I guess looking for a BT connection? Any ways is there any reason I shouldn't leave it plugged in? Not that is should matter, but it's an ELM327
 

fralexandr

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Apr 26, 2007
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The newer versions of the ELM327 (1.4b and newer, 1.4b has probably been out since at least early 2012) have low power drain/idle modes (~50mA @ 12V). Older ones could be problematic if left in (though drain rates are pretty low anyway, I think some of them approach 1-2w).
http://www.elmelectronics.com/obdic.html#ELM327

Some cars turn off the OBDII port 10-30 seconds after engine off.

edit: Thus I suppose, the older ones could drain a car battery in ~2 days, vs the newer ones in ~8 if my calculations are correct (based on a 12v, 40Ah battery, 75% required to crank) assuming no other source of phantom drain
 
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QueBert

Lifer
Jan 6, 2002
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thanks for the post, I'll leave my car off and check to see see if the lights still are still blinking after a minute. I don't see any model # so I'll have to dig around to figure out which reversion I have.
 

DaTT

Garage Moderator
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Feb 13, 2003
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My OBD port is in such a place that it's uncomfortable to leave it plugged in while I drive.
 

SandEagle

Lifer
Aug 4, 2007
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haven't used mine in years. always unplugged because i too read about the battery drain
 

Zenmervolt

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Oct 22, 2000
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Thus I suppose, the older ones could drain a car battery in ~8 days, vs the newer ones in ~33 if my calculations are correct (based on a 12v, 40Ah battery) assuming no other source of phantom drain.

A car will refuse to start LONG before the battery is completely drained. The starter pulls a lot of amperage and a battery that at even 75% state of charge may not have enough to get the engine to crank.

ZV
 

fralexandr

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Apr 26, 2007
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A car will refuse to start LONG before the battery is completely drained. The starter pulls a lot of amperage and a battery that at even 75% state of charge may not have enough to get the engine to crank.

ZV

Thanks, o_O good to know. It would explain why someone on amazon had their car die after 2 weeks. Also why they couldn't get the rv to crank in breaking bad ;).

I'll edit my previous post.
 
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SparkyJJO

Lifer
May 16, 2002
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I prefer to not leave extra stuff plugged in to add to the parasitic drain on the battery more than what there is already, particularly in the winter!
 
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