Battery Charger Connection

[John Vance]

My CTEK 4.3 charger often displays an error indication when I arrive at my hanger before a flight. I connect the negative side to the lower cowl bracket, which appears to provide an acceptable ground. I've noticed that the connection to the positive battery terminal, through the wire that FD provides for that purpose at the lower cowl, seems a little touchy. A slight repositioning of the charger clamp on the wire helps, or sometimes not. I've tried using contact cleaner, but that doesn't seem to make a difference. Has anyone else experienced a similar problem and found a solution?  

[John Vance]

I've tested both the muffler and the bracket with my multimeter and the bracket is actually better.  There's no paint on the surface I clamp to, and I keep it clean. The problem seems to be the wire.  

[John Vance]

I replaced the battery about 30 operating hours ago, so it was good at that time.  It's been about that long since I've checked the grounds, so I should probably check all of these again. When I connect the charger to the wire, sometimes it doesn't start going through the steps until I reposition it on the wire or wiggle it. Yesterday when I arrived it was stuck on step 1 with an error light.  I used contact cleaner on the wire and bracket and reconnected, no luck.  So I twisted the clamp on the wire a little, and it started walking through the steps nicely.  I wondered if there might be some surface corrosion and whether a dab of conducting grease might help.