I have too recently fitted a 12V Bluetooth monitor, probably the same as BatteryLife, since the app looks the same.
Rather than play with the 12 battery terminals, I found a more convenient and easily accessible place to fit it.
Under the +12V cover, mine had a spare terminal which I used for +12. For the –ve, I used the nearby headlight mounting point.
Yes, I tested it before fitting, both seemed like a reliable source for the 12V and less risk of disconnecting the battery inadvertently.
Why is there a plastic bag stuffed in here? (Red Arrow)
Now the interesting bits…
During a home charge, the 12V is charged as well, monitor showing approx. 14.9V. Nothing new here. We all know both batteries get charged.
When HV finished charging, monitor shows 12.7V. I was hoping it would be higher, but that is what it is for mine.
I left the granny charger plugged in overnight to see if there was any ill effects. I can only say there was no significant 12V battery drain. Next day 12.69V.
The key fob proximity does affect the car! As I approach the car, the fob starts to blink, I guess forever (well at least 5 minutes). At this time the battery voltage drops to 12.1V. My take is that the car awakes and obviously draining the 12V somewhat. Unfortunately I don’t have a clamp meter to see how much current was being drawn. But I suspect it is not a trivial amount.
I hung around for another 5 mins and key fob still flashing and battery monitor still at 12.1V. Could this be the infamous battery drain? The key fob being too near the car???
I moved away until the fob led stopped flashing. About 3 minutes later the 12V started to creep back to 12.6V. Car must have gone back to sleep.
I repeated this, but put the fob into a metal biscuit tin, but near the car. Same effect; well, we know a metal tin cuts off the signal.
As already stated, the mains was still plugged in, but finished charging, so the charge port light was off.
I used the App to initiate preheating. The charge port light came on (green) and I could hear some fans coming on. The house meter was showing a draw of 3KW. Good, it was preheating from the mains and not the HV battery. The battery monitor showed it was charging at a measly 12.9V, if one could call it charging.
I gave it 5 mins and unlocked the car. BTW, mine is setup to unlock when I touch the door handle, not as I approach.
When it unlocked, the 12V battery was still charging at 12.9V. However when I sat down, the charging voltage jumped to 14.9V. Yay, it was charging properly. The fans were still belting out due to preheat. So I turned them off.
I sat in the car for 15 mins playing with the menus to see if I could fathom the headlight setting (to set it so we drive on the left)… For another episode.
Having the key fob too near the car, keeps the car awake and probably drains the key fob as well.
I suspect my battery is on the verge of dying. 12.6V locked and key fob far away is not high enough in my books.
A 15 minute charge/drive per day is not really enough to keep the 12V battery from dying since I lost 0.1V in this one off experiment and the 15min charge was not enough to replenish the 12V drain.