I'm sure this is child's play for an Electrical Engineer

[Jack Olsen]

On track days, I run a video camcorder, which uses rechargable batteries, and a lipstick camera, which uses 8 AA batteries, and I'm now also going to be running a DL-90 data acquisition thingy.

I've got cigarette-lighter adapters for the video camera and the DL-90 box, but of course, I don't want to actually have things popping out of my cigarette lighter when I'm driving. (Besides, what if I take up smoking?)

So, I'm thinking I could tap into the power line that feeds the interior lights, and have that feed the adapter for the video camera. I can also tap into the old radio power feed, and have that supply the DL-90 (and also my transponder, now that I think of it -- jeez, I've got a lot of gadgets).

But here's my question, is there a Radio-Shack method of replacing the 8 AA battery pack with the feed from the car's 12V power?

I know there are volts, amps, impedence and those kinds of issues to tackle -- and I assure you, I have a hard time understanding any of them.

Any suggestions?

[JWest]

Well, most often 1.5 Volt batteries are wired in series so the voltage is additive. 1.5X8 = 12V. I'm sure it does not draw much so amperage is not really a concern - 16 to 18 guage wire will probably do fine. Just tap in to a fused circuit like your other accesories.

BTW, I'm an AE so my answer may not count.

[dhoward]

Solder a couple of wires ( Oh, let's say a red and a black) to the terminals that would normally contact the battery pack inside the device. 8 AA batteries don't supply a lot of current, so your camera or whatever doen't have a high current requirement. Pick up a male/female molex connector and pins (Radio Shack). Crimp or solder 1 pair of pins and a connector to the car side, and the other to the device side.

[IMONBOOST]

I agree with James Adams with respect to the batteries beign in series addign up to 12v, but I would suggest you find out the operating range for the camera since a cars voltage can easily fluctuate from 10 to 14 volts.

I am a Computer Engineer so only my first and a half year at college was equivalent to an Electrical Engineer's, therefore, my answer is still not the most qualified.

[dhoward]

...And sure there's volts and amps and ohms and all that, but for most equipment designed with cigarette lighter power in mind, it's mostly plumbing. So, get out those dykes and wire nuts and have a smokin' good time!!

[Eric86Red911]

First off, verify that your 8-AA batteries are indeed hooked up in series. I don't think you can just assume that it is so. You can inspect the battery connectors or use a volt meter to check the voltage across the 2 wires coming out of the battery holder. If it reads 12V, you're golden. If not, errrr, a little help here?

[dhoward]

If not, you'll need a resistor network or switching power supply to reduce the voltage. Umm... Check the voltage rating on the box, or the battery pack before we start posting schematics....

[dkmartin]

Hope this helps:





There are other ways to draw this and wire this that are essentially the same. This was just a quick sketch for demonstating purposes of your application- so you could "see" what evryone is telling you to do!

[dkmartin]

My diagram assumes each unit is , in fact, 12v and the fuses should be appropriate for each unit (which I have no idea what the amperage draw is of each). You would need an Amp meter to determine the proper fuses, but I would put fuses in to protect ALL of the equipement as well as allow for a fault of (1) unit not being able to affect the others. This means if the DL-90 fails while you are driving and pops the fuse, you will still have power to the camera and lipstick

[Chuck Moreland]

You should be able to confirm the batteries are in series by looking at the battery carrier.

Since the camera and the DL are designed to draw power from the lighter, no concerns about voltage regulation.

If the batteries are truly in series this will be easy.

Doug's drawing needs to be modified, all fused connections need to go directly to the power source eg. Do not put the fuses in series. Ground conections are similarly not in series. I'm sure this is what Doug had in mind, but the picture is unclear.

With an appropriate selection of power source, additional fusing may not be required - but doesn't hurt. Select appropriate fuse sizes for each component.

[IMONBOOST]

I am still worried about the voltage range for a device to work on AA DC batteries. I would suggest you install a voltage regulator and that would garantee you no problems frying the camera. Here is the link for the regulator, it is just $1.49 at radioshack:


Fixed Voltage Regulator 12VDC out

[dhoward]

Ok, now we are talking about engineering a regulating circuit. I don't have a drawing package on this PC or I'd have you something out already Jack.
Chuck's got it right, Doug's drawing just needs a tweek to make it crystal clear..
No need to overthink this......

[dkmartin]

how's this:

[dhoward]

Simplicity itself!
Poultry in motion....

[APKhaos]

Boost is right, Jack - you need regulated DC at 12V.

No reason why all of your gear can't be driven from the car's power, but the video gear is designed to operate on a clean and limited [to 8xAAA] voltage source. Need to protect this from the spikes and noise on the car's power lines. There are several ways to do this, but a simple three pin regulator like this would be fine - I'd use one for the video camera, and one for the lipstick camera. The transponder and DAcq gear have internal regulators designed to handle nominal 12V from the car. A separate fuse for each unit.

The easiest apporach is to put all this stuff in a little box [smaller than a cigarette pack] that you can locate under the dash. Feed it from the cigarette lighter circuit. The box can house the regulators, the fuses for each unit, and the connectors/plugs/sockets needed to plug the units up to the power source. This way everything is nicely contained in one place, and protected.

Would be great if you could find someone on the left coast to help with this. Seems crazy doing such a simple [child's play is right] thing from coast to coast.



Best bet is

[IMONBOOST]

Do what ever you feel like, but I am sure the camera will not withstand a surge of 14 volts. So you can either replace the fuse frequently (Assuming you figure out the correct resistance and not blow the camera) or spend about $2.00 (v Reg + heatsink) and never change fuses. Here you go, good luck and have fun!

[dkmartin]

Remember: this is a race car....wire nuts are light, junction boxes and regulators are HEAVY....at least a couple of ounces, which could rob Jack of a few ponies!!!!

p.s. just kidding, I assumed Jack would install/wire this stuff in a professional manner---the drawing is just to illustrate to Jack how it needs to be done without complicating it.

[APKhaos]

Ooww....OK, make it a little Ti box. The key point here is to provide a compact & secure physical location for the regulators, the fuses, and the connectors.

Light is right, I agree, but Jack does not want a rats nest of wire nuts and crap which is a sure source of unreliability.

[dkmartin]

Ditto-Tony

As for the regulators, the fuses will protect the equipment. He could always add the regulators later if the equipment tends to blow the fuses. Jack's car doesn't have many accesories that would make the voltage fluctuate by that much, however, I DO AGREE THAT THE ITEM THAT IS POWERED BY BATTERIES MAY BE INTOLERANT OF A VOLTAGE HIGHER THAN 12V, SO MAYBE A REGULATOR IS IN ORDER THERE.

[dhoward]

Lipsticks are generally CMOS based with a 1/3 - 1/2 inch CCD and do 12v +/- 10%