Question for battery experts.

Question for battery experts.

I built and installed my city-lights flasher setup. Right now I have the timer set for 28 seconds off, 2 seconds on, 28 seconds off, 2 seconds on..repeating...while the ignition is off (when the ignition is on a relay cuts power to the whole thing).

So, the bulbs are on for 4 seconds per minute. 4 seconds x 60 minutes (hour) = 240 seconds the bulbs are lit per hour. If I park the car at 3:30 after driving home, and I don't start it again until 7:30 the next morning, that's 17 hours. 17 hours x 240 seconds means the bulbs will be on 4080 seconds total per night. 4080 seconds / 60 seconds per minute, means the bulbs will be lit 68 minutes total per night.

The bulbs are five watts, there are two of them. 10 watts @ 12.6 volts is about 800 ma. The timer circuit itself draws about another 200ma, so make it a even 1 amp draw when the lamps are lit.

Will drawing 68 amps out of the battery overnight mean I won't be starting it the next morning?

Yeah, I know, wait until tomorrow morning and see. But if someone tells me it will drain it, I'll go pull the fuse on it now.

This is only until I find some high-bright 12V yellow LEDs. Then this would be moot.

as far as i know, u can leave ur flasher on for atleast 8 hrs before the battery will be dead, but i dont know the breakdown that u just did for ur system, if it works, can u make me one as well???

Man this sounds like my first year electronics exam all over again!

I'm not 100% sure when it comes to car batteries, but i do know that they have a lot of amperage. I remeber wanting to purchase a bench power supply at 30 amps, so that i could simulate a car battery, and i was told by one of my professors that it wasn't even close. Car batteries have a low voltage, but a very high amperage, i'm guessing that you'll be fine for the night (typically 10 hours). BUT DON'T QUOTE ME ON THAT!

I have a good friend that is an electronics mechanical engineer, teaching at my college. First thing tomorrow, i'll send him this thread and i'll tell you what he thinks 8)

It's working as we speak. Looks either nifty, or "ricer". :?:

But my wife called me a "geek".

Sure I'd build you one. It was somewhere around 40 bucks, without the light sockets. Toyota wanted 20 bucks A PEICE for the real city light sockets. Screw that, I found some generic sockets at AutoZone for 3 each.

I just found the LED I want to use and used a dropping resistor calculator I found on-line. So I'll be switching to white LEDs tomorrow, and won't have to worry 'bout it.

Oh i forgot to mention this earlier....

would you mind capturing a couple of snap shots of the final product, i'm really curious to see what it looks like...sounds interesting

I'll give it a shot. I've got a ancient digital camera, not sure it's gonna get anything without the flash.

what is the city-lights flasher? does it have something to do with the low beam headlights?

hey 03ToyMan, is there any way i can contact u via AIM or something instead of doint a lots post thread, i had a question bout this and dialup makes it a pain in the ass to keep coming back, let me know or if u want hit me up, the info is in my sig

Not in my case. I bought a timer kit and assembled it.

http://www.electronickits.com/kit/complete/elec/ck1614.htm

I used a 12V 10A SPDT relay from Radio Shack to control when the flasher is active. I tapped off my corner light, when it is lit it pulls the relay in and cuts power to the timer. Put it in a Radio Shack project box and mounted it on the plastic shield under the car on the left side.

The timer is pretty nifty. You can set it to cycle from between once a second, to I think something like 4 days. Was pretty easy to assemble, took about a hour, with interruptions from my family.

Sure, I'm AlwaysOverLoaded on AIM. But I'm heading for the sack now, I'll be on IM about 8 AM tomorrow.

I'll PM you my e-mail address tomorrow also.

J

thanx i'm a total noob when it comes to electrical stuff, i mean i can hook up stuff, but makin stuff from scratch, i dont know how to do it....

When you lights are on, the lights will consume 800 mA, the relay (assuming you're using one) will consume another 200 mA, an the timer circuit will likely consume another 200 mA. When the lights are off, only the timer circuit will consume power (assume 200 mA again). If they're on for 2 seconds and off for 28, the average current draw will be 267 mA. Over a 16 hour period the total energy consumed will be 4.25 Ah. Car batteries are typically rated at 40 Ah, but in practice you don't want to consume more than 10 Ah - once batteries get below 75% capacity their life expectancy decreases. You should be fine, but you might want to get the current draw down either by reducing the on time, or by going with LEDs.

The other night I accidentally left the interior dome light on overnight. It's an 8 watt bulb and was on for about 9 hours. That translates to 5.7 Ah. The engine did crank just a bit slower than usual.

Good calculating oxy, I didn't consider doing a "average" draw.

The car fired right up. I'll get my LEDs today, so looks like I survived Johnny's Latest Frankenstien Project!

Thanks for the replies everyone.

Good stuff 03man, just wondering if you got around to taking a couple of pictures, i'm still interested in what the final project looks like

P.S I love the new avatar...too funny!

Didn't try last night, didn't wanna dig the camera out. Probably can't tonight, since it's raining now and supposed to storm tonight. :cry:

My "new" old car will be here Sunday morning, so I'll have to get all three Toys together, stand my family in front of them and bug the neighbor to press the shutter. I'll get the city flasher pics then too.

I tried to get that pic for the avatar into my signature but couldn't finger out how to do it?