The 12V system: Cars, trucks, boats, airplanes, expeditions, spacestation, hamradio, ... has grown out of and independent from the old ICE car.
There has come so much out of that 12V system that we cannot live without it.
Growing bigger we got current problems. We pushed up voltage to reduce amperes. Cars and trucks and airplanes with 24V, even radio with 24V but they split the battery to allow 12V to coexist and created a big problem. 36V boats and 48V industry automation increased the pile but with dc-dc converters solved part of the problem. the 12V system is now isolated and the higher voltage battery is untapped.
The 12V system mutated into a universal problem solver, growing independent from whatever was feeding it and running from its own 12V battery.
Silently a 120V dc system evolved. You can use much of your 120V ac stuff with 120V dc. For some gear little adaptation to dc is needed but can easily be done. The heart of everything still is an internal 12V dc system evolved from the old ICE car and with a heart of lead more often than not.
With the i-MiEV for the electronics the 12V dc system is still the heart and it works even with the HV disconnected. It is actually what connects the HV in the first place.
When you disconnect the 12V dc the turtle looses all her memory. She no longer knows whether the battery is full or empty. She assumes it is somewhere in the middle and she needs to get to the point where the 2 lower bars are blinking to recalibrate.
There is no need for jump starting like in an ICE car. We do not need to turn a krank. As soon as we feed a little power through the lighter socket, key in ACC position, the battery and 12V system wake up. There are lots of 12V to 12V lighter socket cables available. You cannot jump start an ICE car from them but an i-MiEV you actually can.
I have seen so many silly people recently who were inviting disaster when connecting 2 cars by connecting the 2 batteries. There is an old rule (12V minus ground system) connect the 2 plus poles with one cable first. Now take a deep breath and think again. Do the cables stay fixed, unmoving? When you really feel like it connect the grounds with another cable.
Unplug the ground first and on both sides! Unplugging the plus cannot do harm now.
Simple rule. Is it really necessary - I am a hamradio operator after all and know what I am doing? Yes it is. You cannot imagine what can go wrong and how silly people including me, can be. A short can wreck both cars!
Those lighter socket to lighter socket cables have fuses on both ends and the are big enough for us even to "jump start". A modified 12V charger can do too. Just replace the alligators with a cigarette lighter plug. As soon as you switch the key from ACC to ready the builtin DC-DC will do the rest for you and now you can use your EVSE again.
Peter and Karin Dambier, DL2FBA, www.piraten-fraktion-bergstrasse.de