I'd always wanted to put a dashcam in my Honda S2000.
But the S2000 is a different animal. I didn't want to tackle the power like I had done on my newer Hondas. But the cigarette lighter in the S2000 is on the bulkhead behind the seats.
Then I came across some OBD power cables. There are a variety of alternatives with various connectors, e.g. mini-USB, micro-USB, USB-A.
But the OBD port supplies power even when the ignition is off. Some of the OBD power cables have a "smart" switch that gives 2 different modes. The first is always on, at least until the battery runs down. Unless your dashcam has a motion sensor that will cut it off when no motion is detected, that's not what you want.
The other mode on these "smart" switch OBD power cables is called "ACC". It kills the power 5 minutes after the car is turned off,
The one I ended up with was the Universal OBD Power Cable for Dash Camera,24 Hours Surveillance/Acc Mode with Switch Button (Mini-USB).
But I'm cautious of recommending it just because of the seller. The seller is in China which normally takes several weeks for delivery. But that seller offered "Local Express Shipping" with expected delivery in 1-2 days. I opted for that.
It didn't work out so well. The shipping took 3 weeks. When I tried to contact the seller, the e-mail address that Amazon had failed. But it did arrive and it was well packaged.
Overall, the cable does exactly what I wanted it to. There are several observations to add, though.
The OBD connector doesn't have any mechanism to secure it to the car's OBD port. I'm not sure that that is even possible but since my car's OBD port faces downward, I'm worried that the connector will just fall out.
Similarly, the mini-USB connector seems loose in the mini-USB port of the dashcam.
But it hasn't fallen out.
I'm using the "ACC" mode.
The other consideration I ran into as I researched these OBD power cables was that sometimes they interfere with the normal operation of the OBD system, even sometimes affecting operation of the car.
Toward this end, this OBD power cable only uses 3 pins.
So far, so good.
This looks like the exact product from an on-shore seller. This one has a USB-A port so you could power anything with a USB-A cable, e.g. a GPS or a cell phone.
This has also led me on a quest for other uses of the OBD port. Since the S2000 sits in the garage all winter, I have a battery maintainer for it. But the battery maintainer uses alligator clips that connect to the battery terminals. This means that to connect the battery maintainer I have to open the hood.
This cable plugs into the OBD port and has a connector for the battery maintainer!
I wonder what else I can use the OBD port for?