12v aux battery drain when PHEV locked/unlocked

[martini]

I was told recently by a Mitsubishi emergency assistance guy that it is best to leave a PHEV in the locked as opposed to unlocked state when considering current drain from the 12v aux battery. This seems counterintuitive to me as I assume the alarm will be drawing current when set.
Can anyone tell me, from a current drain viewpoint (car security excepted and of course one would always lock the car when not in a secure garage), whether it is better to leave the PHEV locked (alarm set) or unlocked (alarm unset), what are the relative current drains on the 12v aux battery?

 

[anko]

This is very interesting. I have three OBD Link MX OBDII adapters in my car. Usually I can connect to these while my vehicle is charging on the driveway. Sometimes, I cannot. At least not to all three of them.

Usually, unlocking the car allows me to connect. But I don't really see a difference in voltage on the OBD connector. At one time I actually opened a ticket with Scantools.net to ask if they could explain it.

 

[misterbishi]

I was investigating my parasitic drain this evening and connected my multimeter in series with the battery to measure the current drain, so I can tell you with the doors closed and after all the systems have settled down there is a ~20mA drain with the doors locked and alarm on and ~10mA with the car unlocked.

I must thank you for your post because I've also determined that my parasatic drain was due to the boot being open. It seems that if any of the doors are open, then there is a constant 1A drain on the AUX battery which does not seem to settle down no longer how long I monitor it for Close all the doors and after a short time the drain drops to 270mA for around 5 seconds, then 10-20mA.

 

[anko]

Not simply lights, I suppose?

 

[misterbishi]

I turned all the lights off. Interestingly though they seem to draw around an amp each which makes sense for 12V bulbs.

 

[martini]

I was investigating my parasitic drain this evening and connected my multimeter in series with the battery to measure the current drain, so I can tell you with the doors closed and after all the systems have settled down there is a ~20mA drain with the doors locked and alarm on and ~10mA with the car unlocked.

I must thank you for your post because I've also determined that my parasatic drain was due to the boot being open. It seems that if any of the doors are open, then there is a constant 1A drain on the AUX battery which does not seem to settle down no longer how long I monitor it for Close all the doors and after a short time the drain drops to 270mA for around 5 seconds, then 10-20mA.

Thank you for this reply, very helpful and rather reinforces my thinking despite what I was told by the technician.
Can I ask if you have the WiFi enabled on your PHEV?

 

[anko]

I turned all the lights off. Interestingly though they seem to draw around an amp each which makes sense for 12V bulbs.

Just to make sure: I meant interior lights.

 

[misterbishi]

I turned all the lights off. Interestingly though they seem to draw around an amp each which makes sense for 12V bulbs.

Just to make sure: I meant interior lights.

That's what I thought! Turning them on in turn increases the current drain by around 1A each. I checked the specs on a replacement bulb website and it seems about right. I will definitely be considering changing them for LED bulbs.

To answer Martini's question: yes I do have the wifi enabled.

 

[user 3409]

This is very interesting I wonder where the 1 amp is going. I often have my tailgate open for long periods of time as my car is a Commercial and I am working out of the back of it accessing tools etc. That sort of drain is quite significant and could cause me problems in cold weather with a battery that's not in its youth.

If I get chance I will conduct the same test to see if my van does the same thing.

 

[martini]

I turned all the lights off. Interestingly though they seem to draw around an amp each which makes sense for 12V bulbs.

Just to make sure: I meant interior lights.

That's what I thought! Turning them on in turn increases the current drain by around 1A each. I checked the specs on a replacement bulb website and it seems about right. I will definitely be considering changing them for LED bulbs.

To answer Martini's question: yes I do have the wifi enabled.

Thanks for confirming the WiFi question, assume this will account for some of the current drain although I understand from other forum posts that the WiFi closes down after 36hours if the car has not been used.

Does anyone know if having the bonnet open causes a drain on the aux battery? It definitely causes a “Close Bonnet” alarm when the car is in the “Ready” state but not sure if this relates to a current drain when the car is turned off.