You're right in that the part on the battery terminal is just a shunt and the system basically works by 'counting' amps/hours out and back in to keep the battery at around 70%. If you have an issue with charging or battery you'll have to use a diagnostic tool of some description to reset it - as when replacing the battery.

Just be aware that you can't test the charging without a road test. At idle it'll only kick out around 12.9V. Max charging is measured on over-run i.e. downhill.