Elm327 wifi OBD II scanner - battery drain?
 

I've been using one of these as an OBDII scanner with OBD Fusion app on my iPhone.

I noticed that when the car is off, the LED still blinks, and I can see the device in my wifi connection settings on the phone, so its still drawing power.

Power consumption is listed at 0.75 watts - is this amount of draw negligible, or could it drain my battery in short order?

I put my try-hard hat on and did some back of the envelope calculations. :write: Care to check my work?

Watts = Amps x Volts, watts=0.75 and volts=12.

So 0.75 = Amps x 12 means the draw in amps is 0.0625 amps.

The battery is rated for 36 amp hours, so 36 amp hours divided by 0.0625 amps gives me 576 hours, or 24 days.

Sound right? :scratch:

yes, it can drain your battery down... if you leave it and don't drive several days, like anything else left on....

Leaving it on all the time could cause premature wear on the OBD dongle as well

Some units have an auto shut off after a few minutes but then they usually got a button to activate them again.
Your calculations are correct but on the other hand I wouldn't totaly trust that 0.75W spec so probably better just to remove it.

its probably fine to leave it in. I know people use the live readings instead of using the real gauges. I dont use it but I have left my plugged in for well over a year

It's a possibility that the scanner could drain your battery rather rapidly. It specifies a drain, but doesn't specify under what conditions it produces that drain. Usually with OBD scanners, you get what you pay for. Many of the scan apps warn people away from the cheaper models.

I use this model OBDLink LX and leave it plugged in 24/7 without issue.

Glad you started this thread as I was trying to figure out what was killing my battery when my S sat for weeks at a time.

Sorry to bring this thread back from the dead.... but what live outputs can you get by using this type of connector? I know that the app you use probably matters, but from a technical standpoint, what is physically readable?

I suspect these will read anything on the OBD2 buss with the right software. These just pair your phone which needs software/app in it go do anything. Some apps just look but won't touch anything.

-- Chuck