Schedule of deferred tax asset valuation allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Valuation allowance, beginning of year	$ 9,717	$ 10,310
Allowance for related party note receivable		(65)
Inventory		1
Net operating (loss) income	2,179	(406)
Property, plant and equipment		(27)
Stock options		(57)
Research and development credit	25	(32)
Warranty and other sales obligations		13
Deferred revenue		(10)
Accrued compensation		(10)
Valuation allowance, end of year	$ 11,921	$ 9,717