Murray
Sorry to be insistent here but IF everything is 'secure' AND you are seeing this high discharge with everything that's not needed turned off I'd be checking the crimped terminals. ie B lead from alternator to shunt to bus & the 2 shunt wires to Dynon.
If you're satisfied that the system is working ok, ie the volt meter is working correctly, the
indication of a high discharge is
usually caused by the wiring issues as indicated above.
We had another contributor with a similar problem but persistence finally paid off for him
BTW - what engine/alternator do you have ? B lead fuse ? or Circuit breaker ?
Jake J