I got a better trick that Marvin (ladogos) showed me that works really well and now I never have problems with getting my units to charge. After you clean them up good with a tooth brush so that they are charging good. Then when they are done charging just wrap them up with electrical tape. The tape covers the contact points and they never get dirty or exposed to all that mud and crap. And as a bonus I use different colored electrical tape for each one of my collars so that it is easy to identify which one is which.
Sounds like a good idea, i was thinking of different colored ducktape last night. I was thinking about wrapping a small piece around the antenna's.
Yeah, i turn my power points to the dogs chest. keeps them pretty clean. If you put them outside, they are always full of mud.