12 Volt Battery Drain Measurement
I finally got around to measuring the 12 volt battery drain on my 2015 ED as I mentioned earlier - but the story ended up becoming more complicated than just a measurement.
Test:
To take the measurement without damaging the multimeter from the initial power supply inrush current when the battery is reconnected, I first connected a jumper across the negative terminal and ground so I could, as fast as possible, disconnect the jumper and connect the multimeter.
But with the meter at fused 0-200mA range, upon connection the meter fuse still blew. So I switched to 0-20 A unfused and at about the same time (by coincidence or something i did?) I heard the battery pack contractor close, even though the key was not even in the keyswitch. The meter showed reverse current (i.e. negative to chassis) at about 1.3 A and creeping downward. The battery showed 13.4 volts and rising (resting is < 12.8 V). So the car had turned the DC-DC converter on all by itself and the battery was charging.
After maybe 10 minutes, the I heard another thunk of contactor opening and the current switched to normal flow first at about .9 amps for a few minutes then down to 50-60ma (0.05 A on the meter becasue I had to use the high range) where it stayed for at least 1/2 hour until I ended the test.
Conclusions:
1. It seems that at least some 451 ED's DO have a program routine to keep the 12V battery charged while parked, on some kind of schedule or triggered by some condition. Everybody should check if there is powertrain control unit flash update available for their VIN. I recall that I got some kind of flash update on my ED on the first service visit in 2016.
[edit - it was the second visit in 2017]
2. Assuming this periodic charging from the HV battery does not occur, then with a 60mA draw and the equipped 42 ah battery, the car will draw the battery down in 29 days - or say 20 days with a reasonable safety factor. The car then goes into "suicide mode" after that. How long it takes to drain the HV pack in suicide mode is still unknown...
3. Considering the consequences, I'm still going to connect a charger to my 12V battery if the car is going to sit more than 2 weeks just to be safe.
I finally got around to measuring the 12 volt battery drain on my 2015 ED as I mentioned earlier - but the story ended up becoming more complicated than just a measurement.
Test:
To take the measurement without damaging the multimeter from the initial power supply inrush current when the battery is reconnected, I first connected a jumper across the negative terminal and ground so I could, as fast as possible, disconnect the jumper and connect the multimeter.
But with the meter at fused 0-200mA range, upon connection the meter fuse still blew. So I switched to 0-20 A unfused and at about the same time (by coincidence or something i did?) I heard the battery pack contractor close, even though the key was not even in the keyswitch. The meter showed reverse current (i.e. negative to chassis) at about 1.3 A and creeping downward. The battery showed 13.4 volts and rising (resting is < 12.8 V). So the car had turned the DC-DC converter on all by itself and the battery was charging.
After maybe 10 minutes, the I heard another thunk of contactor opening and the current switched to normal flow first at about .9 amps for a few minutes then down to 50-60ma (0.05 A on the meter becasue I had to use the high range) where it stayed for at least 1/2 hour until I ended the test.
Conclusions:
1. It seems that at least some 451 ED's DO have a program routine to keep the 12V battery charged while parked, on some kind of schedule or triggered by some condition. Everybody should check if there is powertrain control unit flash update available for their VIN. I recall that I got some kind of flash update on my ED on the first service visit in 2016.
[edit - it was the second visit in 2017]
2. Assuming this periodic charging from the HV battery does not occur, then with a 60mA draw and the equipped 42 ah battery, the car will draw the battery down in 29 days - or say 20 days with a reasonable safety factor. The car then goes into "suicide mode" after that. How long it takes to drain the HV pack in suicide mode is still unknown...
3. Considering the consequences, I'm still going to connect a charger to my 12V battery if the car is going to sit more than 2 weeks just to be safe.