A ground wire can be Naked in Fact... no harm in grounding the Ground Wire...
Grounding the plus side of the battery however... breaker suffers... if yer wired with all [including the Voltage regulator] fed thru the main breaker...
good point
I think it was making a poor ground because it seems to be working now
Glad you resolved your problem....not a poor ground but a ground fault or short to ground. You may want to check your charging system too i.e. rectifier and breaker