I need to automatically start my car for a set amount of time

>>1123455
You can get a remote start kit. Is your battery draining or something?

Well, seems like a descent job for a cheap volt meter and an arduino.

Not smart enough to help. Bump for interest tho. I would like to rig mine to a timer. It doesnt have remote start but m-f i start my car af the same time.

>>1123457
Yea, it doesnt like the cold. Also its just getting old, but its got plenty of juice to start the car. I just cant leave it sit for a couple days or else I have to jump it. But if I let it run for 20 minutes It will start up the next day.
Just cant justify the price of a whole new battery yet.

Also after dealing with this, I jsut want to know the car is watching the battery for me.

right now my concerns are the car wont shut off and will drain the tank if I dont hear it running (i should but covering bases here), and my biggest concern is the device tries to start the car again when its allready running.. need a good way to detect the car is running. Im thinking of having it only work when voltage is (9.5V < volts && volts < 11V)

This way it (with a nonfailing alternator) will not start when the car is running since the on voltage should be around 14V, and if it doesnt have enough power to turn over the motor it wont even try, so it doesnt burn out the starter motor.

>>1123458
>cheap volt meter and an arduino.
Thats my thoughts, but Im not sure how Id go about feeding data from the volt meter into an arduino though

(btw its cheaper to just buy atmel chips with the arduino bootloader in it. arduino costs around $40, the parts cost just a few cents each, the whole thing can be made for $5.)

Sounds more like an job for some relay and an Voltage sensor.
Sensor closes circuit of continuous plus to relay and the relay closes the ignition circuit. A second sensor opens the first circuit if the alternator comes in.
Also make sure you are in neutral.

All in all I wouldn't recommend to do this in the first place. Recondition your Battery or buy a quality one from the net.

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>>1123455
Just buy a battery tender there like $20

>>1123465
>neutral
Its automatic so its in park whenever Im not there. Id probably get in the habbit of using the parking bread too, not that it actually stops the car should it really want to go
>dont do it
Yea Im weary of this too
>buy a battery online
The price of shipping legitimatly terrifies me. Id rather buy one locally.

Thanks for the suggestion, I often forget about analog

>>1123472
>Output Voltage: 12 Volts DC @ .750 MA.
what the fuck...

Just get a capacitor bank and hook it up instead of a convoluted idea like this. You can buy 12v caps with more than 200mf of capacity to easily start your car. YouTube has plenty of test Vids and tutorials.

>>1123475
thats a trickle charger, car should not be pulling anywhere near 0.75A when off, and probably 0.1A max - otherwise, Problem Houston - vampire/parasitic drain somewhere.

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

- check that first, what it dont say there, some modules may take 30 minutes or more to shut down. If thats all good, where is the problem? You should be able to leave your car with a good battery (near 13v) 30 days plus, and it'll start. Mine currently, battery half-fucked (ca 12V max charge) - still OK 7-10 days. And if your hitting 10v or whatever, you already lost.

So either your battery is fucked to begin with, your leaving shit on unnecessarily, you have a drain somewhere (hidden lo-power boot bulb that dont switch off or some shit), alternators fucked (should read around 14v), you running a disco as soundsystem, or, your leaving your car for really extended periods.

Regardless, I'd agree with previous, a device that switches a car on remotely by volrtage drop is a fucking moronic idea, especially on an automatic. Might get you on local TV tho as remote murderer celebrity. And how the fuck are you bypassing the 'foot on the brake to start', or, was it only mine you needed that?

All figures random plucked from ass BTW, should be more or less correct tho.

>>1123606
Not sure where you are or what you're driving, but I've never seen a vehicle that you have to put the brake on to start. To shift out of park sure, but not to start.

>>1123612
Automatic, i thought most of them you needed to do that?

Random: http://www.driving-test-success.com/driving-articles/driving-automatic-car.htm

>Ensure the gear lever is in Park (P) and that your foot is firmly pressing the brake pedal before starting the engine, as most automatics will not start unless these precautions are taken.

Personally, Yurope, only automatic I actually had was a vintage BMW 7 - that certainly went nowhere without 'foot on brake first' and Im fairly sure, one or two others Ive driven were the same - manual, fuck no, and, obv. not ALL automatics need this, as noted. Just most of them ;) maybe not Murica..

>>1123571
The fuck? 200mF @ 12V can supply 2.4A current for 1s. If you mean RC car, yeah it could probably start. You would need at least 50F, if your car would start in 3s

All good but how you gonna bypass the key code?

>>1123461
I had this problem too. Get a solar panel for the car.

>>1123647
Great thing about a solar panel is you can just plug that thing into the 12v power point inside the car and toss it on the dashboard

>>1123618
Interesting. All the cars I've driven start with no brake, but only if they're in park or neutral. If the transmission is in drive or realfast 1, 2, or 3 they won't even turn over, brake or no brake. Standard is a whole different story.

>>1123455
instead of doing all this stupid bullshit why not just find the problem? its probably just a small drain from a light bulb or something easy to fix. even if its the battery, you probably just need to top up the acid.

if you want to get stupid about it, you are going to hack some wires. get an arduino, run a signal from your battery through a voltage divider and into an analog input pin. find the wire from the ecu that goes high when the car is running and send that to a digital input. find the start and run wires from the ignition and send those to a digital out. program accordingly.

you are basically building a remote starter that starts based on voltage rather than remote signal. go look up the wiring for a remote starter for your car to find out what wires you need to hack

>>1123650
Anything small enough to fir on dash will do nothing to keep a battery topped off

>>1123455
>I need to automatically start my car for a set amount of time in the event of the voltage dropping down to 10V or 11V.
>starters usually need 12.7V to crank over sufficiently and have enough juice to fire the plugs
think about what you just said, and then make sure you belong on /diy/.....

>Does anyone have any suggestions on how to determin when the voltage level is reaching unnaceptable levels and trigger the car start/stop?
yes, its called buy a new fuckin battery you cheap piece of shiet, preferably one that is above the manuf's suggested CCA so even when one cell sulfates, it still has enough oomph to crank over your spoiler'd-out VTEC Civic.

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>>1123679
if a dashboard solar panel doesn't keep it topped up when the engine is off theres a major parasitic draw

>>1123664
I've driven standards that required the brake to be pressed to start more recently. Seems to be a thing with recent vehicles

>>1123706
I never said 12.7 was needed and it sure the fuck isnt.
Ive started my car many times with it at 10.xV.
Maybe do some research before you try to talk shit off of /b/

>>1123606
Id rather not have to un/plug the car in every time I go anywhere.
Also I misread the rating as 0.75 ma the whole time I was reading it, probably due to being tired.

Thanks for the link and info, Im sure there is a parasitic draw and will look for it, but thats probably unrealted to this issue. The batter is 10 years old and is really just shot. But since it will fire a the car up 3 days later, and since its rare for me to not leave for 3 days, I cant really justify the price.
I took it in to get it charged one day about 2 years ago, they tested it and said "the batter is no good. we charged it anyway but its so far gone the car wont even start". I took it home and the car fired right up, and ive been using it still this whole time with no problems other than what was caused by corroded terminals, which was promptly fixed.
My problem is the drain of the battery itself and mostly this cold weather. I killed the battery trying to start the car, and the car also doesnt like the cold. Starts just fine on the first try all summer, but once winter hits its over.

>moronic idea, murder, and bypass brake
If it was that dangerous then remote start would have been outlawed years ago.
On my car, automatic, inorder to start it, all you have to do is turn the key. it will stay in park (whichs acts like neutral) until you (have to) press the brake and shit it into drive. It wont go anywhere if you dont press the brake, but it wills start just fine.

>>1123618
>most of the do that
crazy, I had never even heard of that being a thing. Maybe things are just more relaxed here in 'murica, or maybe its the same saftey standard (have to press the brake before moving) but they just applied it to putting it in drive instread of inorder to start it. It acheives the same goal, though ours makes reaching in to start the car when worknig on it easier.

>>1123461
Dude, your battery is failing, time to get a new one. Whatever you rig up may work for a month, and then one day that will be it.

just get the new battery now and save the hassle.

>>1123650


>>1123647
those are worse than trickle chargers, especially in winter where there is no sunlight and 2-6 inches of snow on the windshield

>>1123664
Thats how mine is. Its nice if the car dies on the highway, just pop it in neutral and restart it. God help you if you accidently shift into reverse though.

>>1123667
>if you want to get stupid about it, you are going to hack some wires. get an arduino, run a signal from your battery through a voltage divider and into an analog input pin. find the wire from the ecu that goes high when the car is running and send that to a digital input. find the start and run wires from the ignition and send those to a digital out. program accordingly.
This is what I needed to hear, thanks. I didnt know the ecu had a wire that goes high just when the car is running.
Does it go high when it is starting too or just when it is running?

I have access to the complete wiring diagrams for my car too btw.

>>1123455
Didn't read the whole thread but.....
Just buy a new battery, it's only gonna get worse from here on out. Or you can keep a battery charger/conditioner plugged.

>>1123776
I accept this as fact, though it will probably extend the usage of this batter another year or two. And then the system will allready be in place for when the new battery fails.

>>1123779
Why don't you just fix it?
Get battery tested for free at autozone
use meter to check current when turned off.
start pulling fuses until it stops.
replace fuses and start disconnecting things on that branch until you find the one that's draining the battery.

Legalwise, there are several places that have made it illegal to allow a car to run unattended since it attracts thieves or children or whatever.

You will spend more time and effort jury rigging this thing that adds points of failure to your vehicle than just fixing the damn thing right.

>>1123612
You have to put the clutch down to start Hyundais

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>>1123455

this shit is fucking moronic

just disconnect the battery with this every time you know you're not going to use the car

If you run your battery to failure, that failure can sometimes take out your alternator too. Weak batteries are also harder on starters than one that holds a good charge.

Disconnect battery ground when not in use and get a fucking battery soon.

>>1123782
modern car batteries don't slowly decline and die, they catastrophically fail. Don't expect 1-2 years, expect 1-2 weeks.

>>1123782
Sounds like you have a parasitic drain and battery that's gone to shit because of it. You need to fix the drain and just buy a new battery. Go to Autozone or whatever your local low-cost auto parts store is and buy one. They're not that damn expensive, especially if you're willing to shell out on equipment to rig something up that starts the car automatically.

Also, 10-11V is low for a nominally 12V car battery; I wouldn't trust it to start the car at that point.

>>1123461
>Can't justify $100
Get a fucking job.

>>1124686
>sometimes
the problem with modern alternators is they can output 120+a

and they fucking will until they burn themselves up

>>1123461
how about instead of putting all this effort into this dumbass idea you spend that time looking for a job.

Or just suck a few dicks real quick to raise the money. Probably only need to suck like 8 dicks. big fucking deal.

>>1124714
walmarts value line new car batteries start at like $60, one from a recycler or junkyard for less

>>1123455
its illegal to leave a car running without someone to attend to it. if youd ever had to repair an auto gear select mechanism you'd understand why its a bad idea. if the switch is out of adjustment it can drop it into drive or reverse without moving the gear selector.

This is one of the worst ways I have seen some one tried to solve a problem..
You are making this problem way more difficult to solve than it needs to be..

Buy a new battery, if the battery is not that old, then buy a trickle charger. This is way more efficient and cheaper in the long run. The fuel consumption will add up.. Cycling you battery increases the wear. Your idea also results in unnecessary wear on the starter motor..

If you do continue your weird idea, then: A better "on" signal would.be from the alternator, is has a wire to show that is is charging. Or 12 v from the headlights.

Find a off the shelf MCU. Pic, renasas or Atmel no big difference. Be sure it has a build in Adc..

sage because Im done here.

>>1124714
>>1125053

It gets deader over time.
Im sure there is a drain, but the damn thing is 10 years old so drain or not, the battery is fucked.
It doesnt just die overnight, but if I dont leave for several days then it might be too low to actually start, but that takes days, weeks in the summer.

asfor shelling out money, this whole thing can be rigged up with bits of wire and some relays I have sitting around with an off the shelf $2 micro controller, or without one like some other anon suggested.

053 is sorta right though, the problem cant get much worse but I am just prolonging the suffering, or maybe just inventing mad savings. Either way.
It probably would only need to run for 20 minutes a week

>>1124737
>>1124746
Make me.

>>1124865
No it isnt, maybe some places, but not here.