1906a656_uide_to_Small_Batch_Composting__POSSIBLE_CAUSE
[SYMPTOM] Compost has a bad odor like ammonia. [POSSIBLE SOLUTION] Mix in some dry carbon material. Maintain proper moisture control. [POSSIBLE CAUSE] 
Most likely it has too much nitrogen in the mix.
How to Compost: Guide to Small Batch Composting
POSSIBLE CAUSE