M800 70mai 4K (Sony Starvis2 IMX678)+(IMX662) RC14 -1080P eMMC SlimLine Dashcam LN

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70mai M800 Dash Cam Review​

The 70mai M800 is a compact, display-free 4K dash cam that prioritises a discreet, "set and forget" installation. By moving away from a traditional screen-based design, 70mai has created a unit that is remarkably unobtrusive while maintaining high-end optical specifications.
I have been playing with this unit since August 2025 International release but keep in mind what I have found may have been updated since then.

Discreet Design and Ease of Installation​

The primary strength of the M800 lies in its physical footprint and mounting logic.

• Low-Profile Mounting: The design allows the unit to be mounted higher on the windscreen than most competitors. This makes it significantly less intrusive to the driver’s line of sight and far less obvious to passers-by.
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• Mounted to the windscreen. Note the pad on top of the M800 that helped reduce the vibrations. This is my personal experience with an early release unit.
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• Dimensions:
  • Front Camera: 107.7mm without a lead plugged in x 38.4mm including protruding lens x 27.5mm.
  • Rear Camera: 43mm x 30mm x 28mm.
• User-Friendly Ports: Both the power and rear camera ports are conveniently located on the right-hand side of the unit when viewed from behind.
• Proprietary Cabling: The rear camera utilises a proprietary connector. It ensures the user cannot accidentally plug the leads into the incorrect ports during installation. I prefer USB-C ports however.
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• Mounting System: The camera is held by a robust metal bracket featuring an easy slide-in lock system, making it simple to attach or remove the unit when necessary.
• Sliding bracket mount is a neat solution.
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• 70mai stock image showing the metal bracket installed
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Technical Specifications and Optical Hardware​

The M800 does not compromise on hardware, featuring a high-performance dual-channel setup:

• Front Sensor: Sony STARVIS 2 IMX678 (4K) with an F1.7 aperture and a 140° field of view. (*As per published information)
• Rear Sensor: Sony STARVIS 2 IMX662 (1080p) with an F1.55 aperture and a 130° field of view. RC14 rear camera *
• CPL Filter Note: At present, there is no CPL filter manufactured for this unit, though this may change as the product matures.

Optional Enhancements​

To expand the functionality getting a 4G hardwire modem kit is an available add-on.
This allows for real-time remote access (when combined with a SIM), cloud event storage, and battery voltage monitoring with user-definable cut-off levels to protect the vehicle's battery level.

Practical Considerations and Limitations​

Despite the excellent physical design, there are several "buts" that a potential owner should be aware of:

Stability and Vibrations: Due to the overhang created by the mounting bracket, the camera can suffer from micro-vibrations on rougher road surfaces. I placed a thin piece of rubber between the unit and the bracket that helped to reduce the micro vibrations. As mentioned above, this may have been resolved since August 2025.

The Storage Bottleneck: The built-in 128GB eMMC is marketed as "worry-free," but it presents significant practical challenges:

• Memory Corruption: If the internal memory enters a "read-error" state, the unit will announce: "The built-in memory isn't ready. Please format it, and then connect to the computer." I couldn’t find a way to bypass the message. I was hoping I could use Windows disk repair when connected to the computer but it doesn’t allow access when in this state.
• Here is an example from the app with this error.
• I find this unacceptable and a repair process needs to be created.
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• Slow Data Retrieval: With no removable SD card, you must offload footage via the camera's port.
• At speeds of approximately 18MB/s, a full download takes nearly ~two and a quarter hours, preventing the use of the camera as it is unable to record while doing this.
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Summary:

• Things I like are the size and the high quality image on the front Sony IMX678 sensor the compact size of the unit and neat sliding bracket mount.
• 70mai has released a new app that has improved the way you can select the camera you have if you have say two cars it only requires you to drop down the menu to select the other.
• When I was supplied the M800 I was advised that it uses a capacitor however I noticed it took quite a long time for it to shut down which indicated it is using a battery. I asked this question at the time and it was confirmed it uses a capacitor. It seems I was misinformed as the specifications show it uses a 500mA battery.
• I trust that 70mai resolved the vibration issue on later releases so this may no longer be an issue.
• I have also requested that the cable be moved from the side of the camera for two reasons
  • 1. Untidy cable management
  • 2. Having the cables on the end of the unit applies pressure on the sliding bracket and over time it may introduce the M800 to move while driving.
• The rear camera is using the Sony IMX662* but being 1080P seems so low a resolution since the front is 4K UHD.
• Two things that prevent me from purchasing the M800 is the built in memory and the use of a battery. Again I have to qualify this and say I was supplied an early release so things may have changed.

If 70mai made this unit again with microSD, Capacitor/s, Firm non micro vibration and moved the cables and upped the rear camera resolution then this would be a neat little unit.

Here is some real time footage with audio for the first section of the video to help hear the cabin recording.

 

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Here is a video showing the internal battery and the quality of workmanship of this unit.
I made this video for people who want to see how to access the battery and then go on showing some of the internals.
Mainly for curious minds with time on their hands.

I found an extra button i haven't seen in the manual.

70mai M800 Disassembling To Access Battery

 

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For those who want a quick how to find below an abridged three-minute video demonstrating how to open the M800 to replace the battery.