Mine using every day since June 2016 Until today.
No problem.

Change battery.

Mine still can last about 1hour plus.  Same batt since new.

same with my SJ4000...same battery since new and lasts about an hour+.....

and ive never used the charger that came with the SJ4000

always phone charger... USB from PC/laptop etc etc.

if i go for long rides ill plug it into my USB charger on the bike or powerbank in jacket pocket and ride and record.
all ur batteries lasts 30 mins only? if u wanna change, then i think a camera upgrade might be time hahahahahhaa

where you got sj4000? i lookup online got so many ridiculously cheap price. seems not legit.

you bought at shop or online? im looking at online via shopee scared kena scam. prefer buying cod. but cannot find any shop sell one