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The 12V battery location: At the front of the car, betwen the firewall and electric front motor. It is under the plastic cover, at the back of the front "engine" bay.
The 12V battery location: At the front of the car, betwen the firewall and electric front motor. It is under the plastic cover, at the back of the front "engine" bay.
Thank you! I still cannot find this in the NA manual.
Just following up on this. If you remove the panels at the base of the windshield (no tool required), you can see the battery from the side. It's fairly well buried in the center. Here's a couple photos:
The manual reference stating that the 12v battery can be discharged while sitting implies that there is no charging feed from the HV battery to the 12v battery. My i3 did have this, so it's lack means that if one does mostly in-town driving, the 12v battery may not ever be fully charged.
1, The HV battery charges the 12V battery when the car is on ignition or in drive.
2, The HV battery does not charge the 12V battery when the car is on charger/charging.
3, There is no clear answer from the "mothership", that the HV battery charges or does not charge the 12V battery when the ignition is off. They got two different answer from Germany, they are still waiting to be confirmed one way or other.
The DC/DC converter that charges the 12V battery from the HV battery would definitely have the current capacity to charge the 12V battery quickly (perhaps less but in the general range of an ICE alternator).
Disconnecting 12V charging when the car is off is no different than an ICE vehicle. I actually wouldn't want it connected/charging when the car is off. First there's the static load of the DC/DC converter. Second, and more importantly, I can deal with draining an inexpensive 12V battery. Draining the HV pack if something gets left on for long time would be a painfully expensive mistake.
I don't think e-tron does this but perhaps there is a nice middle ground where the 12V battery can be charged if it gets too low and the HV pack SoC is above a threshold.
If the HV battery charges the 12v battery when the vehicle is "on", I think that's good enough to deal with the problems I've had with both BMW and Porsche. When I was doing a lot of in-town driving, the charging profile of those two cars would not run the alternator hard enough to replenish the 12v battery's use for the starter and after a couple of weeks of short stop driving the 12v battery would be "flat". I had to keep the cars on an auxillary charger. The HV battery surely has enough capacity to replenish the 12v battery quickly, plus there is no "starter" load. So, It appears that there is little chance of the 12v battery not being regularly recharged to full capacity. In my 2015 BMW, the 12v batteries were being replace as a matter of course at the 2-year point because the charging profile had the alternator feeding it only on coast down and over run (an attempt to maximize fuel efficiency). BMW found out that the 12v battery was never getting fully charged with short trip driving using this regime.
05-16-2019, 12:28 PM
