Best non-alarm theft deterrent?
#62
TECH Senior Member
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Originally Posted by NoTicketsPlease
Here is my setup. I guess I dont understand why the cig lighter doesnt work. When the relay is triggered it closes the 30/51 - 87 circuit. The 85 - 86 circuit stays closed as well correct? Doesnt that mean current is still running through the cig lighter and it should heat up? What am I missing here?
Originally Posted by WhiteBird00
No, electric current always follows the path of least resistance to ground. If you reconnect the original lighter ground and then tap into it for power to the relay coil, no current will flow through the coil. Even the small resistance of the coil is more than the straight path to ground so all the current will continue to flow through the original ground path.
There is also no way to prevent a wrecker or flat bed from towing the vehicle. That would be considered a hard core thief. Best defense against that is Lojack or some other type of tracking device. I think some thiefs will drop off the car after stealing it if they suspect a lojack and then wait to see if it is recovered. After a certain amount of time, they'll take away to be stripped or whatever. There are a few different traacking devices, you need to see what your city uses. Plus some can be tracked by the owner through cell phone towers and costs a lot less.
#63
Ungrounded Moderator
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Originally Posted by NoTicketsPlease
Here is my setup. I guess I dont understand why the cig lighter doesnt work. When the relay is triggered it closes the 30/51 - 87 circuit. The 85 - 86 circuit stays closed as well correct? Doesnt that mean current is still running through the cig lighter and it should heat up? What am I missing here?
A cigarette lighter works much like a dead short in a wire. It passes so much current that the element heats up. The heating causes the retaining clips on the side to bend and release the lighter element so that it pops out.
When you wire the relay coil inline with the lighter (series connection) it acts as a current limiter because of its resistance. Although current still flows, it is reduced and that keeps the lighter element from heating up (or makes it heat up very slowly).
#65
Ungrounded Moderator
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Originally Posted by NoTicketsPlease
Okay, now that I understand why it doesnt work, how do I get it to work?
You could try connecting the relay in parallel with the ground (i.e. tap into the ground wire but don't pass all current through the relay) and add a resistor matching the relay coil resistance inline in the original ground wire. This will cut the total resistance to ground in half and still provide current through the relay coil. Cutting the resistance in half should be enough to let the lighter heat up since there wasn't much resistance to start with. Make sure you get a resistor rated for the proper current flow.
Another alternative is to use something other than the cigarette lighter as your trigger. I've had great results using the dome light switch portion of the dimmer switch. When you turn the dimmer all the way up until it clicks you're actually closing a separate switch unrelated to the dash dimmer. It is a grounding switch that gets input through the gray wire and goes to ground through the black wire. Since most people seldom, if ever, use that dome light feature, you can cut the gray wire and use it for the ground of your relay. When you want to activate the relay just push the dial all the way up until it clicks. You could retain the dome light usage and just tap into the gray wire rather than cutting it but that means your dome lights will turn on when you activate your relay.
#66
TECH Senior Member
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Originally Posted by WhiteBird00
You could try connecting the relay in parallel with the ground (i.e. tap into the ground wire but don't pass all current through the relay) and add a resistor matching the relay coil resistance inline in the original ground wire. This will cut the total resistance to ground in half and still provide current through the relay coil. Cutting the resistance in half should be enough to let the lighter heat up since there wasn't much resistance to start with. Make sure you get a resistor rated for the proper current flow.
What about a little button where the other 12v lighter circuit is under the hand brake?
#67
Banned
iTrader: (115)
Simple way is a ground interupt with the battery. But you lose your pre-sets on the radio. Wiring an interupt to the fuel pump is a good idea as well. In the end if someone wants it bad enough they'll get it or vandalize it. Make sure your insurance covers what you have into it and keep your receipts. Bout all you can do. Keeping a low profile helps a lot as well. Advertise and you'll get attention. I've seen POS cars broken into just to get the change that was seen in the console.
#68
Ungrounded Moderator
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Originally Posted by JasonWW
A regular resistor may catch fire if you don't know what your doing. I wouldn't recommend that. Try it my way just to see if it works. If it doesn't, then we can try something else.
In this case, unless the ground wire is small enough to create enough resistance to divide the current flow (which we know it isn't), all current will flow directly to ground through the ground wire and the relay won't trip.
#69
TECH Senior Member
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Originally Posted by WhiteBird00
You know, one of the interesting things about electricity is that there are certain principles that govern its flow. These laws can be expressed mathematically, they never change, and everything about current flow in a circuit can be calculated without a need to "try it just to see if it works".
In this case, unless the ground wire is small enough to create enough resistance to divide the current flow (which we know it isn't), all current will flow directly to ground through the ground wire and the relay won't trip.
In this case, unless the ground wire is small enough to create enough resistance to divide the current flow (which we know it isn't), all current will flow directly to ground through the ground wire and the relay won't trip.
NoTicketsPlease needs to learn too. Just trying things is like learning from experience. Yes, technically it shouldn't work as resistance will always take the path of least resistance, but it might. Wouldn't it be great if it did work?
#72
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IMO, the only real deterrent is full coverage insurance. If they cant drive the car, they are more than likely going to damage the inside in a rage of fury.
Most of the worthless criminals around here are meth heads and they just want something inside the car that they can pawn for a quick fix anyways. An autolock is a good idea, but it wont stop a broken window and a stolen head unit/damaged dash.
Sad world that we live in.
Most of the worthless criminals around here are meth heads and they just want something inside the car that they can pawn for a quick fix anyways. An autolock is a good idea, but it wont stop a broken window and a stolen head unit/damaged dash.
Sad world that we live in.