Just made a not-so-fun and dangerous discovery: I melted 😳😳 the EcoFlow car charging cable that has a 12v utility plug on one end and an XT60 plug on the other end!!
The cigarette adapter that plugs into the 12v utility port is not capable of handling anything more than 8A of charge current. I was using this to charge the LTO battery pack in my son's car and I discovered that it wasn't providing the level of charge that I was expecting each day (his battery was losing voltage instead of gaining voltage). As I unplugged things to check it all out, I discovered that the plastic end, just below the metal tip that hits the +12v contact at the bottom of the utility plug, had melted and it was no longer making consistent contact.
I am rather surprised and disappointed. The EcoFlow wire is 14g, so it can handle plenty of current. The fuse in the tip of the plug is rated at 15A, so it can also handle plenty of current, too. But the metal +12V spring loaded contact heats up the plastic tip to the point where it melted and deformed with a 9A current flow! The EcoFlow can be set to charge at rates of 4A, 6A, or 8A. So, at an 8A charge rate, it's fine, but at 9A charge rate, it melts?!?!?!
So, the bottom line is that the EcoFlow utility plug is protected by a 15A fuse, but melts with a 9A current flow👎 It serves their needs (seems to work with an 8A charge rate), but the plastic melts and deforms BEFORE the fuse blows... That's some bad engineering!
I think it is not the current itself that melted the plastic but a poor contact resulting in excessive heat.
That cigar lighter connector is really old and bad design.
Plug’s tip is spring loaded and due to vibrations it pushes the plug out of the socket, which in its turn, is a smooth cylinder without any real locking features.
Finding the good socket-plug combination is almost impossible, because socket is part of the car and because of dimensional tolerance of 70 year old design.
Here is what I do to improve the condition:
Start with quality plug with copper tip and copper spring. (replace the spring if not copper)
Slightly shorten the spring between the tip and the fuse (by cutting or deforming) so it doesn’t push out the plug as hard.
Abrade inside of the socket cylinder with rough sandpaper to create some friction.
I actually deformed one of my sockets out of cylindrical shape a bit, and even melted some solder inside the socket-the only solution that really helped.
On current:
Keep in mind that if charging current into the Battery is 8A, then current out of car would be higher due to charging efficiency and other losses, including bypass power to dashcam in my case.
So if charging efficiency is about 90% the current out of the car is about 8.9A (assuming the charging voltage and out of car voltage is roughly the same for LFP).
My Jeep cigar socket is rated to 13A, but I limited the current out of the car to 10A max and adjust my charging current accordingly. This is because of heat generated by the cigar connector and also, wires behind the connector look like 18AWG to me.
Most car cigar sockets are limited to 8A-10A, this is why dedicated batteries limit the current to about 5A, using the cigar socket.
