You are right.
The car battery is considerably cheaper at only A$200 each, while the Egen Cellink Neo is about A$350 each, so it makes much more economic sense to use the vehicle's PbSO4 battery than a LiFePO4 battery pack in the glove box.
I bought my Cellink Neos brand new for less than A$300 because there was some special at the time, however they have been running since late-2017 fine.
After about a year, park recording off the vehicle's PbSO4, the engine startups were difficult, so we quickly switched to dedicated glovebox battery packs.
All depends how much park recording you do I guess.
It does cost a bit more, but everyone is different; we "personally" prefer the safety of separating the dashcam from the motor vehicle's battery pack for reliable engine starts.
Especially in Australia because local batteries in Australia are now ALL
maintenance-free types nowadays.
In Australia, they have stopped making batteries with six removable caps to top up the water; this is a shame, because a bit of manual topping up with demineralised water can make the PbSO4 last so much longer, with less damage to the environment.
Because maintenance-free batteries are "sealed" so they can't be topped up with demineralised water - the battery's longevity is even more shortened, and is now down to as little as 2 years.
Just me only, but I am uncomfortable with parking dashcams compromising the already short maintenance-free battery life even further.
Nowadays, we personally have four (4) dashcams per vehicle too, including two StreetGuardian SG9663DR's on the rear door left and right vent fixed panes, and that really drains the battery while parking.
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