Flat 12v Battery

Went to the car today - completely dead . .

It was my fault, I was playing about with a new OBDII device last week and left it plugged in. It obviously draws power even when the car is shut down - it says it (the OBD) powers down when not used, so I suspect that it is not the case. It is a generic WiFi model.

I did not use the car for a week, so I think that the device slowly flattened the battery. That's all I can think of, as I have not had anything else in the car that could have affected it.

I called Mitsubishi Services (MAP) and they sent a breakdown service within 45 minutes - pretty good service. The mechanic used very long jump leads back to his vehicle - he said that for the PHEV and also other EV vehicles, the separate "booster" type devices didn't work - he tried it to show me and the car failed to recognise it. As soon as the long jump leads from the truck were attached (same points) there were beeps and clicks from the car and it allowed me to press the "On" button and start the car / engine charge.

I was wondering why the 12v battery had not been charged by the main battery overnight and I "think" I read somewhere that if WiFi services were off (|no devices registered) then the overnight top-up was ignored. I have registered a device now, just in case. Am I correct in this assumption?

Jeff

I have a dashcam running 24/7, car is often left for a week or so without being moved. Do have two phones registered though, and a small lithium booster pack as recommended a year or so on these forums!

Thanks for the response. I will see how it goes. I do have one of the portable li-ion battery packs but it is in my wife's car and she was out! I will have to buy another one. That being said we left her car for 4 months when we were on a cruise and it started first time when we got back to port and the PHEV was OK as well, so go figure.?? I can only assume it was the ODBII that caused the problem.

Jeff