i have front and rear dash cams wired for some time so i will tell my experience of hard wired and not so hard wired
the cameras i use are these which iv'e had for a couple of years or so
DDPai M6 plus DDpai Mini 1
the front ( m6 plus ) is hardwired straight to battery live but is magnetically mounted and can be removed easily when not needed leaving just the mount in place
the rear camera ( Mini 1 ) is wired through ignition live and is in place permanently switching on with the ignition
both have 128GB micro sd cards installed
both are WiFi and connect to my mobile via an app although for normal operation the phone app is not needed once set up
iv'e experimented with the rear camera using a power brick to power the camera whilst the ignition is off and get a full 24 hours out of a true 6 amp hour power brick from a full charge
if you use a power brick with fast charge ( type C connection ) and use the car daily you stand a chance of keeping the power brick charged enough to keep the cycle
something i found hard to do and ending up disconnecting the power brick over night when the car was parked putting the power brick on charge on the weekend to fully charge ready for the next week which worked
using 128 gig micro sd cards gives me about a week of continuous recording from the front camera bearing in mind when the car is stationary ( parked up ) the video goes into time lapse mode after a short time of inactivity until woken up by sound rather than movement
the cameras draw about 220 mA each so not a lot of current drain and doesn't really effect the car battery with the front camera wired up for a week which i have done on a few occasions
i would imagine cameras with built in screens would draw considerably more current but they usually have an option to turn the screen off
these cameras are getting on a bit now and have been replaced with newer models but they still do the job and video footage is quite acceptable
the trouble with the budget cameras iv'e had in the past tend give poor video quality and quite a few of them which say they are 1080p resolution are really 720p which is something to watch out for if considering the budget brands
an example is one of these
Find many great new & used options and get the best deals for Dash Cam USB 1080P FHD Car DVR 2MP Camera Video Recorder 170° GPS ADAS G-sensor at the best online prices at eBay! Free delivery for many products!
www.ebay.co.uk
there's a varied amount of these all over ebay boasting 1080p / wifi and a bunch of other wonderful features
the reality is there 720p no wifi and need connecting to an android phone/tablet via usb ( OTG cable ) to set them up via a very poor app
they do use a micro sd card up to 32Gb but there pretty poor
i suppose the price reflects the quality considering i paid less than £12 for it
