Mystery power drain from mains

[Alternative]

I checked my house energy use this morning and where it would normally read 100 Watts or so, it read 1.3kW.
I tracked it down to my i3 which had finished charging 11 hours ago, but was still plugged in. I had set no timers or preconditioning and yet the car was taking 1.3kW? Temperature outside was 7C. When I unlocked the car, the EVSE clunked and the consumption ceased, but when I locked it again, the consumption resumed. I removed the charging plug and replugged it and now everything is normal again.

When the car was consuming the 1.3kW, the EVSE charge light was illuminated, but the car and the App was not reporting charging. I wonder where the power was going?

 

[jadnashuanh]

It might be the process of leveling out the charge on the batteries. Once the car reaches what appears to be 100%, not all batteries in the pack may be exactly full, so the car can do a process to try to bring any low packs back up to full. That process can take awhile, and not sure when it happens, but it may not be an extension of the original charging process. Course, there could be something wrong in the car, too!

 

[i34me]

We had a similar experience before (an unexplained 1.3kw draw) and not long after the 12v battery had completely failed.
Just guessing... it may be trying to charge a failing 12v battery.

 

[PhilH]

We had a similar experience before (an unexplained 1.3kw draw) and not long after the 12v battery had completely failed.
Just guessing... it may be trying to charge a failing 12v battery.

That would be around 100 amps into the 12v battery. Seems unlikely.

 

[i34me]

We had a similar experience before (an unexplained 1.3kw draw) and not long after the 12v battery had completely failed.
Just guessing... it may be trying to charge a failing 12v battery.

That would be around 100 amps into the 12v battery. Seems unlikely.

You're right, but I don't believe the 12v is charged directly from the wall unit. The 1.3kw (about 3.5amps) would be for the main battery asking to be topped off, after a constant drain from trying to charge the failing 12v. That may not be likely, but it did seem reasonable to me.

 

[jadnashuanh]

As I understand it, there are two paths to recharging the 12vdc battery in the i3...the normal way is during vehicle operation or charging when the main battery tries to maintain the accessories battery. The second path is if the main battery and the 12vdc battery are both so discharged the 12vdc battery cannot sustain power to the computers...there's a secondary circuit that will charge the 12vdc battery until the computer can start up, then things return to the 'normal' path. That secondary path should never be needed, but is a fallback for worst case scenarios.

Battery leveling does occur, maybe not every recharge cycle, but at least periodically. Once fully charged, the logic doesn't turn the EVSE back on again until the main battery has dropped a bit, and that normally takes days unless you've asked it to precondition or set a departure time.