Other assets (Details) - USD ($)		Dec. 31, 2018	Dec. 31, 2017
Consumer battery license fee	[1]	$ 400,000	$ 450,000
Long-term rental deposit		243,128	298,431
Other Assets		$ 643,128	$ 748,431

[1] The Company is amortizing the $1,000,000 cost of the Consumer Battery License Agreement with a License Provider over a period of 20 years on the straight line basis in accordance with the terms of license.