Blind spot camera

First, blind spot mirrors are easy. Other than the many blind spot mirrors for mounting outside, I prefer bigger mirrors for mounting inside. You just need to mount near the side mirrors but inside, facing a little more outward than the side mirrors. If you mirror is fairly big, you just need to check if you can see the back corner of the backdoor window. And for those newer utility cars where you can just pry off the trim and put it back with your fingers, mounting on the A-frame is trivial.

The problem with blindspot mirrors is that, if they are not permanently and securely mounted, you don't know if they are even there at night when there's nothing bright at the back for you to see. Also, you still have to look left and right and up (for the rearview mirror) if you want to be safe. With a cam or cams, you should just need to glare slightly down on the dashboard instead of the windshield.

First, instead of left and right cam and some split screen viewer, just a single wide-angle cam will be fine. It's like something called lane-changer mirror; it mounts on top of the rearview mirror giving you a continuous semi-circular view on your back and sides. The problem of this kind of mirror is that you see the rear passengers as well, blocked by them or the interior of the car. It's perfect if the lane-changer can be moved a bit backward to the windshield at the back. But then you can't see the mirror anymore. A cam will solve all problems.

Now, of course, you need a wifi cam to stream to your smartphone. A wired cam with its own monitor isn't at all bad. You still need wires to get power to your cam and phone.

You need a night vision cam that sees through the glass from the inside of your car. Those relying on infrared LED won't work. Dashcams are perfect as they all work at night from the inside.

You need a mirror of the image facing backward. If not, it will be like flipping the view of the rear mirror horizontally, left becoming right.

So I bought one more YI dashcam. Everything is good except for the mirror image. There's no app for that. So you need some silicon pad to keep your phone level on the dashboard, and a real mirror standing up about 45 degrees up. That would be something like a HUD converter for phones mounting on the dashboard. But you need to cover the back of the semi-transparent "mirror" with black paper to increase the brightness.

You need a phone that can stay on maximum brightness for hours without getting too hot. And you need one where the adaptive brightness can be turned off. Some cheap phones cannot do that.

The best mounting position of the cam is the top middle of the rear windshield, pointing slightly down to a lot down.

With a wide-angle cam, things at the back are a lot smaller. But that's OK. As long as you can see something at your back, it's close enough not to brake suddenly. And the cars on you blindspot are very big, closer to you than the cars following you.

In the daytime, mirrors are superior when there is plenty of sunlight. The phone screen looks dim in comparison and it's hard to see because of the reflections from all sides onto the phone and then onto the mirror. At least you need a piece of black cardboard to shield off reflections from the top of the windshield.

The cam image is perfect on a rainy or cloudy day where you can see which car on which lanes at your rear. It's also very good at night to detect anything at your back. You can see headlights a mile back. But you shouldn't rely it as a lane changer on a busy freeway because all the headlights at your back will be confusing. Use it as a rear warning signal. On a road with occasional or moderate traffic at night, you can drive with your head on a pillow without moving.

The YI cam is OK but the software is not perfect for this application. There is a video server on the cam so you don't need to have an additional wifi router onboard. Indeed you cannot because the software is proprietary.  However, the video startup connection is pretty slow. It's not like you switch on the engine and drive away. Though you can make the connection once you drive away.

The startup is a bit clumsy for real-time streaming. Assuming the YI app is already started, you need to tap on the connect button. When the connection is completed after a few seconds, you need to tap on the full-screen button that is tiny! But why? So lame design! Then you need to tap again to get rid of the camera icon for you to take pictures with one tap. Also, the orientation of the image is fixed. For some phones, you also have to tap again to get rid of the "no internet" warning.

As for the mounting, the easiest is using transparent mailing tapes. You make a cardboard box to hold the cam. There should be taps, wings, or extrusions from the box for you to tape it onto the rear windshield. With tapes, you can take it off anytime without marks.

You can mount your cam with magnets outside at the top of the rear windshield. You need to weatherproof the cardboard cam housing which is easy. You also need to have enough super magnets for your maximum speed. But the problem is that you need a small cam with an unnotable housing. People are nervous around cameras.

For the YI cam, you still need the SD card or the image will be jerky. Your phone also cannot be too old. Some quad-core phone works smoothly but some don't.