Hi guys,

I'm starting to suspect something (maybe I am wrong) and will be nice to see if anyone had/has similar issues.

I started to get low battery warning when starting the car for a couple of days now and its been bugging me why. I remembered the issues I had with resetting the "oil warning message" - because I had the OBD2 scanner connected - and I removed it. I stopped getting the low battery warnings right away after that... and this made me wonder...

If you leave an OBD2 Bluetooth scanner connected to your car... will this drain the battery of the car?
Could this also create the additional, unwanted, effect like getting weird check engine light messages or any other electrical gremlins?

I had other makes and models of cars in the past and never had issues leaving a scanner connected for years... but I'm starting to think that maybe in the Jaguar world leaving this connected all the time is not a good thing!?
I read a few post regarding similar issues with other Jaguar models - something along the lines that the car doesn't actually "go to sleep". Will this be the case for this model also?

 

From memory, the OBD2 standard dictates that the power to the socket (pin 16) is always on rather than switched +ve, so any device plugged into the OBD2 will always have (and draw) power, even when the car is switched off and the doors are locked. It's obviously down to the vehicle as to whether this standard is followed, but I'm pretty sure that the XF OBD2 port is not powered off when the car shuts down.

As for whether this will drain the battery of the car - it depends on the device. "Good" OBD2 devices that are intended to be left plugged in for long periods of time like GPS trackers etc should have a "sleep" mode where they draw a very small amount of current (in the milliamps) when the car isn't being used, just enough to keep things alive, and provided the car is not left unused for a long period of time this should be OK - the car's alarm system, for example, is another constant (small) power draw.

However, if the scanner you've connected is cheap and doesn't do this, then it's absolutely possible it draws too much current - especially if it (for example) constantly polls for bluetooth devices to connect to - and at this point you could drain your battery.

Other electrical/unwanted gremlins are entirely possible with a low battery - in fact, these cars are sort of famous for it so I would say with the XFs in particular other electrical/unwanted gremlins are likely with a low battery. When my battery voltage got too low I had all sorts of weird behaviors, transmisison/traction fault codes, even the fuel filler lock motor constantly locking and unlocking.

 

@davetibbs - thank you for this!
Most probably my unit being a little older (I had this for more than 6-7 years now), doesn't have a sleep mode (is an ELM327). I guess for the other cars that I had they were either cutting the power or weren't so iffy at the low battery.

I will keep it unplugged for a while and see if I will still get the battery warning any time soon.
I noticed I usually get the warnings after I leave the car for 2-3 days parked (working from home or long weekends) or after the times when the fans were starting by them self during heavy rains and eating up the battery (you already know my other thread ).

If that stops, maybe is time to upgrade to a new-er and better unit.

 

Yep, lots of battery drain problems reported on the F-Type forum with use of a cheap and/or old elm327.
Bin it and get a better one.

 

Thanks guys! I will take it in the back yard and put it down .
Now I need to go for a longish drive to charge that battery back up .

I'll report back in a week or two if everything is good or not.

 

The OBD adapter in my Volvo is Bluetooth and is lit when connected, so a possible drain at all times. The one in my XFR is Wi-Fi, but I'm not sure if it drains at all. It seems to be a curse of modern cars that spurious faults appear with a low charge. Keep us posted.