Related party balances and transactions (Details 2) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Investment:
Payment of investment	$ 316,484	$ 0
V-Power [Member]
Investment:
Payment of investment	$ 316,484	$ 0

The cash outflow for securities or other assets acquired, which qualify for treatment as an investing activity and are to be liquidated, if necessary, beyond the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the long-term.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

Name:	us-gaap_PaymentsToAcquireLongtermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration