I'd imagine if the car had enough power to switch on the accessories, then it would switch on the Cig outlet, in which case, you can charge through it. They are normally fused at 10A.

Cars with key activated ignitions physically switch on the accessories, but in these modern cars, it takes some power to activate the circuit. It probably just comes down to if the 12v battery has the minimum voltage available to switch it on.

 

Cars with key activated ignitions physically switch on the accessories, but in these modern cars, it takes some power to activate the circuit. It probably just comes down to if the 12v battery has the minimum voltage available to switch it on.

And that brings up the question of what the idle current is for 12V with everything possible turned off but the car switched on. Of the 5A you have available, what'll actually end up as surplus available to charge the battery? Given the plethora of electronics in the car that idle current is probably fairly high.

As well, a source with nominal 12.6V available will charge a depleted battery but won't charge a battery already in a reasonable state of charge. So as RP5 alludes to, it's questionable whether a battery that can benefit from the power source can actually be connected through the accessory socket via turning the car on.

Meanwhile, if the car can be switched on (and hence the socket connected) and has reasonable power in the traction battery, the car will provide far more power to recharge the 12V than what can come through the accessory socket.

 

Hyundai Ioniq's have a "Go jump yourself" button to recharge the 12V from the traction battery. That's a really cool feature and means no more jump starts. I carry a smaller lithium for jumping, either myself or others.

I'm not sure what problem you're trying solve. You'll have to charge your lithium supply from somewhere. All of that power conversion DC to AC to DC has losses at every step. Jumping a car via the cig lighter is generally frowned upon.
If the car is running and trying to provide 12V and then you add your yellow box trying to provide 12V, the stronger supply will treat the weaker supply like a load, not another source. That's why there's warnings on remotes to not mix styles of batteries and/or charge levels within them. Your little yellow box could, in fact, warm up the cabin, but from melting down when it gets overpowered by the car's voltage. Hopefully, there's circuitry protection in both devices to prevent that, but I wouldn't count on it. I definitely wouldn't risk my new 40k car interior or wiring to save pennies of electricity consumption.

I wouldn't worry much about running the defroster occasionally, especially since you're in a warm climate. If you just want to save more dollars, do a better job of finding free public charging or get on your utility's offpeak plan. If you want to increase your comfort, use departure charging. Then add a precondition if necessary.

 

The "Go Jump Yourself" feature also existed in the GM EV-1...22 years ago.

 

My question was not about regular charging, rather when the screen errors come on, and the 12v is unable to draw in the main drive.

It is just that the portable lithium bank people gave me that cord. If the cigarette plug in the Bolt is inactive when the error screen comes on, then I understand that I would need alligator clips straight to the battery.

Was just curious if anyone had tried the cig plug...to help activate everything. Sure, we all know that the main drive bank will then charge the 12v. However, I believe all this rescue to be a one time event, as I would never trust a 12v that went that low once, and even delayed travel once.

 

Ahh, yes, now I understand. I had that problem in my Prius several times - 12V too low to start the car, but the traction battery chock full.
I would still recommend a lithium jumper (and using the battery terminals) should you ever need a jump, but now I too am curious about what the "starting current" needs to be. I would guess the real current needs are minimal.

 

From other blogs on this topic, it sounds like the 12v need only go down near 12.0 to cause failure. No one is talking about 10 - 11 volts in their stories of failure and towing. So, yes, it sounds like a little help would go a long way...to obtain that last latch and engagement of the drive battery. That is when the dealer says "12v battery", tosses your old one, and installs a new one. It sounds like they left very little head room. Think all of us would appreciate a PRIOR warning...that your over all voltage is dropping under load. And that the warning be done long before the 12v can no longer latch in the big system battery. Seems like a couple of software parameter limit changes might keep a Bolt owner from being towed or needing that jump. Of course, the Hyundai technique of drawing on the big battery, no matter what, sounds superior.

 

Just to clarify, there are 2 types of "on".

The first type simply turns on accessories such as the radio and activate the 12v cigarette outlet.

The second type connects the traction battery to the vehicle electronics and puts the car in ready to drive mode.

Turning on the accessories should take less power than switching the contactors that connect the traction battery. Turning on just the accessories should provide the pathway via the cigarette lighter outlet to charge with a portable charger, and that may be just enough to get the car to fully turn on to ready (or whatever they call it on the Bolt, I don't own one).

 

I wouldn't try it. The car is saturated with electronics. Who knows what will happen if you try something that blows a resister or diode, etc. Could be a very expensive experiment. Stick with a portable device that connects with the battery directly.