not sure about specific unit you have.
if it is a 12v battery, and you put a multi meter across the pos and neg posts. a good battery should read above 12v. say 12.4v
when unit is on and running, and the altenator is charging battery, you should get 14v or a little higher say 14.4v
you can take battery out, and most automotive part stores, should be able to do a "load test" on battery as well to see if it can put out the cranking amps (CA)
double check battery also has water in it, if it is old style batteries and not the newer solid state battery.