Have you ever seen either of the above on your EVIC?
I have, twice. First about two years ago when what looked like the battery in my key was on its way out. I popped the key case apart to get the battery number and found that the battery holding clip had pulled out of its solder joints. I re-soldered the joints, and re-installed the original battery which is still working.
Recently I grabbed my wife’s key ring, with the second key for the “C”, to run an errand. This key has NEVER been used to unlock the car remotely. My wife has never driven our 2005 300C. First the key remote wouldn’t unlock the car, so I unlocked it the old-fashioned way by sticking the key in the lock and twisting. That unlocked the door, but also set off the alarm! Starting the engine stopped the alarm. But then the EVIC showed the RKE battery warning.
Subsequently I popped open her key’s case and, you guessed it, the battery holding clip had pulled out of its solder joints! This condition may have existed for nearly three years because we never used the key before.
This time around I decided to snap some pictures before and after repairing the dumb thing. After removing the little screw and popping the case open, the battery literally fell out. The battery holding clip had pulled off of two of its three solder joints. The third joint didn’t look too good either as it had been pulled too, but didn’t pop after the other two joints pulled and released the pull on the third.
As can be seen in the following pictures the battery holder clip is “C” shaped. There are two “into the board”-type connections (one each at the top and bottom of the “C”) and a surface-mounted tab at the left side of the “C”.
From the looks of it, all of the solder joints were “cold” joints, that is insufficient heat was used to allow the solder to properly bond to the metal of the clip. The spring pressure of that centrally located (battery positive +) tab exerts quite a bit of force as can be experienced when inserting the battery back into the clip after doing the repair.
The repair takes a bit of soldering expertise not to apply too much heat, and care not to dab solder all over everything.
First squeeze the “C” between thumb and index finger to reduce its size to
enable insertion of the little tab at the top of the “C” back into the hole in the board. Then apply a dab of solder to the tab at the left side of the “C” to establish a mechanical bond.
Then flip the board over and carefully apply a small amount of solder at the
points where the little tabs at the top and bottom of the “C” project into the
board. Use care to not use more solder than necessary.
Hopefully anyone who had such a failure didn’t have to pay a stealership for a replacement key because this type of failure simply should not occur!