In-car video surveillance?

First-time poster -- love the site, love this family of car, can't wait to own one.

I graduate from college this December (B.S. in Computer Science), and as a graduation present to myself I'm going to put myself on the waiting list for a 2005 Prius. (I'm a 27-year-old bank employee, not quite as penniless as your average college student)

When I get my new Prius, I would like to spend a few thousand to wire it up for video surveillance, for added protection against hit-and-run accidents, random dings and scratches, and proving fault in what would otherwise be a no-fault accident. (And maybe get insurance discounts?)

Well, that's the reason I give my family, who have seen me blow too much money on toys before. I think I just want to do it for fun and for pure geek-cool-factor: I could then use these cameras as a platform for various geeky projects, such as a mobile webcam or something...

I have a friend I used to work with who still works in a local casino's surveillance department as an a/v tech. I don't know much about surveillance technology, but I'm pretty confident when I start asking specific questions he can give me good advice. ("good advice" maybe == "don't do this, you don't know what you're getting yourself into" )

Has anyone ever removed their headliner, ran some wires underneath, and glued it back up? Is that a really bad thing to do to a new Prius?

In a normal car it would be a major drain on the 12V lead-acid battery to run a/v equipment 23 hours/day every day with the engine off. Can the Prius support a large load, like 12V at 1 to 2 A running 24x7, any better than a normal car? Is there any way to (ab)use the high-voltage battery to support some equipment at that kind of load? That's a lot of power -- I'd need three large (and heavy) 24 amp-hour SLA bricks, recharged every day, to supply that much power if I had to bring my own batteries. I guess this is wishful thinking, but I'm hoping I can get that much power from my Prius, maybe at the cost of a few bars of battery charge per 3 days or so. I'd be willing to accept the risk that Bad Things could happen if I went more than a few days without starting the car.

Last, I've heard there are ways of displaying a video signal on the car's display. Has anyone played with reading touch screen coordinates from the display's touch screen hardware? Both of those together might provide a useful interface to a computer (for the passenger, of course )

Sorry for the extremely weird questions, but I'm still brainstorming about what kind of interesting in-car geek projects this car's new technology might enable. I stand a good chance of building something that's never been built before if I'm taking advantage of some feature of the Prius that other cars don't have.

And even if none of this geek-frankenstein-project stuff pans out, I'm still getting the car because it's pretty cool on its own.

--Michael Spencer

 

Great reply, Eisenson, I appreciate it very much.

Hmm...thinking about in-car recharging... at first I completely dismissed extra batteries for power since I'd have to bring them inside and recharge them, and I'd probably forget to do that. In-car charging seems interesting. The only problem with that is, I'd need huge battery capacity and lots of charging current to support a 1 hour on / 23 hours off charge/discharge cycle, and not sulfate the batteries. I'm thinking batteries large enough to charge at C/4 for one hour and a charge rate that would replace 23 amp-hours in one [strike:4c2cd8abf8]day[/strike:4c2cd8abf8]hour. To make it round, 24 amp-hours, *1.5 charge efficiency, *4 so the batteries don't complain about the fast recharge, comes to about 144 aH, or about 1.7 kWh. A single 24 aH battery, over the Internet without shopping around, costs $80 plus shipping and weighs 19.10 pounds. I'd need 6 of those batteries, and would need nearly 500 watts for 1 hour from the car to recharge it while driving.

I know very little about cars, or the power available over various 12 volt "rails" (probably not the right word), but 40 amps constantly for 1 hour seems like a bit much to ask. Right?

So basically, I shouldn't count on a bunch of toys being on and running 24x7 unless I'm willing to do some work to supply that power, like hand-carry 6 20-pound batteries in and out of the house every 2 days. (and perhaps replace those batteries every 6 months)

The Prius is still an amazing vehicle, and (again) I'm still buying one for all of the other reasons. I think I had this mistaken idea that the high-voltage battery system used to power the vehicle was also available to power my goofy amateur projects, and the vehicle's automatic charge management would give me "free power" at a small hit to its already-amazing fuel efficiency.

So I suppose, no matter how much electrical tape I have, I should leave the orange cables alone, huh? That much voltage and current capacity with no circuit breaker between me and the energy source does seem kinda dangerous...

(edit to correct a mistake, above)

--Michael Spencer

 

Thanks for all the great information!

Hmm, I never thought of that: replacing the wimpy just-enough-to-start-the-car 12V battery with a large battery in the trunk, connected to the battery up front via thick cables. What kind of charge current does the Prius give that battery? Does it give that onboard battery the same kind of smart charge it gives the high-voltage system? If so, will it complain about the much-larger-capacity battery? Will it say "there's no such thing as a battery that fits in the compartment with capacity greater than X, and I've been charging at C/4 for that X for 5 minutes and haven't seen a voltage increase. PANIC!"

I've never seen automotive batteries rated in Ah, just cold cranking amps. How do I find the right capacity of battery?

Do I need to worry about reversing batteries, if I have a high-capacity 12V lead-acid battery in parallel with a low-capacity 12V of the same chemistry? Or is it only in series hookups that one strong battery could try to charge a weak battery backwards (after everything's been sufficiently depleted to drain the smallest battery), ruining it?

Also, one problem with a single camera (unless it's one of those expensive HD cameras or something) is resolution: if someone hits me in the parking lot, but my first opportunity to see their license plate has them nearly a car's length away from me, their license plate may be represented by only, what, 20x10 pixels. That's not enough to read fine detail like that.

Well, that's the whole point of this exercise: have the car somehow supply enough power to give me a platform to experiment with. Maybe somehow learn to detect when a reportable event has happened, and collect information intelligently and upload it somewhere. " I've just been stolen, and this is what the thief looks like. I am *here* right now." Mount communication stuff in a lockbox with its own (short-lived) internal power, with a sticker on the outside: "If you can read this, your picture is already on the Internet."

(Or most likely, what'll really happen is I'll buy a few things, figure out this stuff is HARD to implement, and give up. I'm no hardware-hacking genius, I just think this stuff might be fun to play with.)

 

Yeah, I hadn't given much thought to the specifics of the recording setup yet. I just figured if I had enough power to run a laptop or small PC I should be able to do just about anything. Now it seems brute force really is an option: I can put a massive battery bank where the starter battery goes, perhaps keeping the original battery as a backup in case I drain the deep-cycle batteries too much to start the car.

I don't mind the ICE running longer to keep everything charged and happy, but (assuming my projected power consumption is realistic, which it may not be -- 12 watts constant drain, but 400 watt charge current for an hour a day to put it all back) will the car deliver as much charge current as I'm asking? Is it safe to charge those marine deep-cycle batteries at C or higher?

(charging/discharging at C means enough current to equal the battery's capacity for one hour. An 18 amp-hour battery being discharged at C is supplying 18 amps, and will be dead in one hour. A 100 amp-hour battery being discharged at C is supplying 100 amps and will be dead in one hour. A charge current of C/4 is charging at one-quarter the capacity of the battery, which would in a perfect world charge the battery in four hours. (realistically, multiply by 1.5, so 6 hours) This C ratio thing is a good way to measure how quickly you charge a battery, because with most batteries if you double the capacity then you double the amount of current you can charge or discharge. Charging at C is brutal for some kinds of batteries, shortening their life and making them overheat or leak acid; but not a problem for other kinds of batteries. That's why I said I wanted to charge at C/4 before: it's a hefty charge but not too strong, and will fully charge a dead battery in 6 hours. I only have 1 hour to charge with, so my batteries had better be only 1/6th dead after 24 hours.)

(I probably explained the above very poorly, so if it doesn't make any sense it's my fault, not yours.)

Here's hoping my family doesn't read this: I think my real goals for this setup are:

1) It must be safe -- no burning down the car, no causing accidents while driving.
2) It must be an interesting toy. I may change my mind several times and redo things, and hopefully the system I put together will be flexible enough to allow that. Having lots of available power helps.
3) It should eventually be an "install-and-forget" recording system I can forget about when I get bored with it, yet will still be there to protect me if someone scratches/dents my car in the parking lot or causes an accident while driving. (but we all know it'll probably be unplugged/in the house/malfunctioning when it's really needed)
4) It would also be nice if it had some anti-theft use, reporting back to me (and sending data off-site somehow, perhaps via wireless) when someone uses the car without logging in first.
5) Last, it would be nice if I built this in such a way that it didn't make my car look like some kind of science project. Wireless sounds like a good idea.

Thanks again very much for entertaining this goofy idea.

--Michael Spencer