I have a wireless rear view camera in my bumper that currently draws 120mA @
8V DC (in the paper specifications) from a 9V PP3 battery - attachment is a PP3 clip. I tested it out with some of those (cheapo no-name crap) super heavy duty batteries and it lasted for about 30 minutes, which is OK for a quick trip, but any more and it means I have to have a load of batteries with me and keep opening the boot to change the battery over.I tried one of those more powerful (and more expensive) alkaline batteries (Duracell Ultra) - I dunno what their capacity is, I googled and found its about 570 mAh, so I figured I should get a good 5 hours or so, but after just over two, I guess the battery ran out as it stopped working and I had to change over the battery again.
So I guess my problem is capacity - I ordered some 2650 mAh AA rechargeables and a battery block with PP3 connector - I suppose 6 x 1.5 is going to give me the 8V that I need to power this thing for a reasonable amount of time.
I was looking at running this thing from the car electrical system, but I don't have any reasonable convertor and I don't want to cook it with too high a voltage/current.
I have a multimeter and I am finding I am getting 12V DC from a pair of wires near the rear, which will probably be too much, but it says 0 amps? How do I get the 120 mA that will run the device?
I am able to solder and am handy with DIY well enough, so could add in a resistor or two to get it down to 8V, but I'm gonna maybe need some tips on how to do this right without blowing the camera.
It was cheap enough, but repeated learning experiences can get expensive! Please point out any misconceptions or probable pitfalls I am likely to encounter on this project - and any suggestions are very much appreciated!