In case I was not clear, I was proposing hooking the deep cycle battery to the battery in the C-
So are you saying that when the C-Max uses 12 volt power with the key in the engaged position (engine will go on when needed) the power does not come from the 12 volt battery but kind of comes from the HVB, so the 12 volt battery does not really get depleted. If this is the case, then my idea to hook the deep cycle battery to the car 12 volt doesn't do much when the key is on. To keep the engine from running a lot in the cold, it might work to charge the HVB to a high state by tricking the car to think you want the heater on until the HVB is charged. IF this is the case it might be a good idea to use a electric space heater to heat the car with the key engaged.
In the ready to drive position. I have push button start. Yes, the DC/DC converter is supplying the load (like a conventional alternator would do) whether ICE is on or off. But unlike a conventional car, ICE in the C-Max will be off until the HVB is below a threshold level. ICE will then start to charge the HVB up to a certain level and then shut off. This ICE on/off cycle will continue. This is significantly more efficient than running a conventional car continuously for auxiliary power. The 12 V C-Max battery does not get depleted as the DC/DC converter keeps its charge up.
Like I've said several times in other threads, I've done this to keep car cool (AC on) with my dog in the car. IIRC, you have to lock the car with the key FOB. IIRC, the black button on the handles won't work to lock the car with the car in ready to drive. It's probably illegal to leave the car "running" in most jurisdictions. But when I've done it, I've parked somewhat away from where most are parking so as not to attract attention with a pet in a "hot" car and an unattended running car. When I first started do this, I checked about every 10 minutes or so to make sure the all was fine.
Don't know about a keyed ignition system. But I assume that if you start the car by turning the key, you are in ready to drive just like with push button start.
Edited by Plus 3 Golfer, 14 April 2017 - 06:06 AM.