From my experience with a few dead batteries soon after delivery, subsequent use of a battery monitor, and what I've seen online, 12V issues seem to be acute - the system being ~13V at one point, the (DC

C, I'm pretty sure) inverter not coming on to top up the battery when it should, and having a low battery condition shortly after. Furthermore, it appears to be related to some excessive draw, rather than slow recharging. It seems the system checks the battery at some interval, and if the drain occurs in between checks/charges the battery gets too low and since the recharging system runs on 12V, it can't work to save itself.
It does not appear to be gradual - as if the system was somehow not able to keep up and lost some amount each day until it got too low. In this sort of scenario, a monthly external top-up would be of little value, unless you happen to be charging on one of the days the system failed.
Someone chime in if they've had a different experience, but what has been posted to the board seems almost exclusively to be issues in the early days/weeks of ownership. In my case I had 3 or so dead batteries within my first month of ownership and nothing in the ten months since.
I'm curious to hear the details, but I suspect the individual who had the battery drain while the car was not in use did not have it plugged in as recommended in the manual.
Unlike an ICE vehicle, the 12V system in the GV60 charges both while being driven and periodically when off. If things are working correctly, the length of your drives should be irrelevant to 12V battery charge maintenance.
I've attached a few screen caps from my battery monitor to illustrate.
The July one was (I believe) my least dead battery. You can see that the battery went from 13V to 8V in just six hours. No trickle charger would help there.
Here's the narrative on the screen cap from yesterday - a particularly interesting one given the activity during the day.
- The battery got down to 12.65V before the system automatically topped it up just after midnight. It delivered voltage of ~14.7V while charging and brought the battery up to 12.95V when it was done.
- The ups and downs from 6:30-7:00 are while I was driving and should probably be ignored as they were likely driven by different systems going on and off while driving. I arrived at the office and plugged the car in, but scheduled a delayed charge.
- The car begins to charge the HV battery just before 9AM. The 12V battery reaches a low of 12.6V before it also begins charging simultaneously at 9AM. Charging voltage goes from 14.6V to 14.4V before stopping just before 11AM.
- The HV battery continues charging until about 12:15, where we see that dip in voltage, then is flat at 12.9V until 1:30 when I leave the office. It rests at 12.8V while at home for a short while, dips down to 12.3V as I leave the trunk open while loading up the car.
- Again, reported voltage swings up and down while driving ~2:45- 3:15.
- There are some ups and downs at 12.3V to 12.6V as I leave the trunk open while unloading the car. Then remains about 12.8V for about an hour while the car is shut off.
- Voltage goes from 14.4 to 14.1V from 5-8 PM while I'm using V2L. Then is at 13.7 on the drive back home, then remains at 12.9V for the rest of the night while shut off.
Over the course of the day, we see the battery charging spontaneously between 12-1AM, while charging the HV battery 9 - 11AM, while V2L is in use 5-8PM, and while driving ~9-9:30.
Finally, a 15 day graph (the longest period available). The car charges the battery whenever it hits 12.6V. Whenever the voltage appears lower, the car is in use. I wonder if that is a sign of a weak battery - from the three discharges it has suffered.
Does anyone see anything here that would indicate that a monthly trickle charge would be beneficial?