Keeping MS plugged into HPWC...still having vampire drain

[Unpilot]

I need a electric car charging guide for dummies!

 

[RandyS]

For those of you who are using the 12v CTEK quick disconnect and coming out the nose, etc., there is an easier way that several of us have used to connect the CTEK to the 12v system (images below courtesy of Ingineer). Scott mentions this above, but here are some photos that show how to make the cigarette lighter plug hot all the time in the car. Amazon carries CTEK accessories such as a cigarette lighter plug. So all you have to do is roll the window down slightly, plug in the CTEK cigarette lighter plug into the socket and power the 12v vampire load with the CTEK. You'll never forget about it and drive away because the wire goes into the driver's window and it is very visible.

In the frunk, remove the top cover to reveal the fuse and relay bank. Remove the black cover on the left bank and remove the relay as shown. Crimp a short jumper to go into the relay socket as shown and bypass the relay. This makes the cigarette lighter plug hot all the time...Pretty easy to do and once you do this and hook up your CTEK, your car will never lose any range sitting in the garage because the vampire load will be powered externally and won't have to be serviced by the main battery pack...

 

[Veritas1980]

I need a electric car charging guide for dummies!

Why not use Teslas then; A plugged in Tesla is a happy Tesla.

In reality, I don’t think it needs more than that, but it’s fun to discover and discuss the details.

 

[obie_fl]

Keep in mind, while charging the car there's a connected DC-DC converter sourcing from main pack supplying the 12v systems. So the 12v battery is not cycling. It's charge state is being floated by the DC converter. Facelift cars have a better 12v design with an added mini DC-DC converter that supplies 12v keep alive systems directly from the main pack even when the car is not charging.

When a plugged in car finishes the charge cycle it disconnects the big DC converter. The old style cars are now on 12v battery duty cycling... but new cars enjoy the mini DC converter (always connected)

This is the first I've read about a second mini converter on the newer models. That would pretty much defeat the purpose of any trickle charger as the 12v is always floating. So the only time you would run into trouble is if you let the HV pack fully discharge. Interesting, learning more every day.

 

[brkaus]

Keep in mind, while charging the car there's a connected DC-DC converter sourcing from main pack supplying the 12v systems. So the 12v battery is not cycling. It's charge state is being floated by the DC converter. Facelift cars have a better 12v design with an added mini DC-DC converter that supplies 12v keep alive systems directly from the main pack even when the car is not charging.

When a plugged in car finishes the charge cycle it disconnects the big DC converter. The old style cars are now on 12v battery duty cycling... but new cars enjoy the mini DC converter (always connected)

Source? If true, this would explain the minimal vampire drain in my s100d.

 

[scottm]

The mini DC conv in facelift cars is a godsend for 12v battery life... so no, you don't need a CTEK trickle charger in 100D cars.

IMHO Tesla should have done this in first gen cars, the electrical engineering team would have seen the 12v battery cycling issue coming a mile away. Maybe beancounters or production pressure pushed the inferior design out.. or they were really hoping to achieve low standby draw for internet connectivity that never materialized.

 

[jmnieves]

Thanks for the great replies, looks like my HPWC kicked in overnight and charged it back up to 90%.