Like most small automotive battery chargers mine is a piece of crap little 8 amp unit. When I went to use it the connectors were bad and one of the wires pulled out of the connector. Fixed that and there isnt enough spring tension for it to make reliable connection to the battery terminal. By now Im getting a little fumed because I worked to work on my van instead of the battery charger. I had a couple of miniature vice grip pliers, basically toys. I drilled holes in the jaws and tapped them. Replaced the cable on it with some heavy duty speaker wire, I think wires are about #12 and fastened the wires to the screws I installed on the jaws with some crimp-on terminals. These things will now fasten on to anything and break through just about any kind of crud to make a good contact.
Hope this helps someone
Jimmie