Custom replacement for Power Magic Battery Pack?


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Jan 14, 2020
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I will buy a new dashcam in the upcoming days, with special attention to (buffered) parking mode, therefore I'm strongly considering the Viofo A129 Duo IR.
I have read a lot about the advantages of capacitor-powered cams vs battery-powered ones for people living in hot environments. I live in a hot and dry climate, and despite my previous dashcam (Transcend Drive 550 Pro) had a battery source for its parking mode, this never lasted long time, so it was useless if I wanted nighttime surveillance (e.g. my car parked in the street overnight).
Thus, I learned that the best option for capacitor-powered and parking mode is either a battery pack or harwiring. I'm a bit unconvinced of hardwiring, because a) There is always a risk that the cam could drain my car's battery and b) If you got a model with a cut-off voltage threshold, that means that eventually your cam *will* shutdown and stop recording. This seems a bit paradoxical to me, so I prefer the autonomy of a battery pack, such as the Power Magic... but being priced ~USD 150, it's kinda expensive.
If you consider that the Power Magic is essentially delivering 12V power to the cams's cigarette lighter, acting like a UPS based on the attached picture, do you think is possible to just replace this system with a cheaper and simpler solution like a >20.000mAh power bank? I have an Anker Astro Pro Series (20.000) with a 9/12 V output that I use to run something very different (a telescope) for ~5 hours, and a Ravpower (23.000) with a 9/12/16 V output able to energize a laptop (see attachments). I don't know how much power uses a dashcam during 6-7 hours (such as parked overnight in the street), but maybe is not too difficult to handle for these devices.
Maybe my suggestion is nonsense (after all, these power banks can't be re-charged while the car is running) but maybe a similar device can do the same job without spending too much money?. If hardwiring is the only solution, can you confirm that 6-7 hours will be a safe autonomy without draining the battery?
Thanks in advance!


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Jul 7, 2014
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United Kingdom
Dash Cam
Gitup F1+G3ꞈꞈꞈꞈꞈ Viofo A139ꞈꞈꞈꞈꞈ Blueskysea B4K+B2K
A 20,000mAh USB powerbank (75Wh) will run the A129 Duo IR for 24 hours.

Your car battery will do the same if you drive for 1 hour per day, or 30 minutes if your car has an AGM battery (as used for stop-start vehicles).

The disadvantage of a USB powerbank is that you need to charge it every day and most 20,000mAh powerbanks take around 8 hours, so it can't be done while driving. The car battery will charge while driving.