DIY Batteryless SmartTag

[stupidcar]

I think is a good idea but not recommended. Will fry the chips inside later.
Like they said in car chargers are not good for our phone. Eventually our phone battery lifespan ends faster.

Voltage in the car is not stable. Can be high or low at times.

That where a calculations of resistor needed.
Put a resistor that resist 4 volts.
Car: 12V
Needed: 9V

 

[shiroitenshi]

That where a calculations of resistor needed.
Put a resistor that resist 4 volts.
Car: 12V
Needed: 9V

Actually car is not 12V, car is 14.5V. 12V is the battery, once you start your car, the alternator kicks in and you get 13.5-14.5V, I always use 14.5v for car to calculate resistance required based on voltage and amp draw.

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[stupidcar]

Actually car is not 12V, car is 14.5V. 12V is the battery, once you start your car, the alternator kicks in and you get 13.5-14.5V, I always use 14.5v for car to calculate resistance required based on voltage and amp draw.

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Really?
If i resist base on 12V, my leds are gonna burst!

 

[shiroitenshi]

not really, overvolting leds a bit don't usually do much apart from shorter lifespan. overvolting a lot that usually kills it.

But yes, you can try with a multimeter to see before and after you start the car. its 11-12, before start, 13-14.5v after start engine and it runs the alternator.

dont test at the ciggy plug area, rarely you get full voltage unless its a new car.


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[stupidcar]

not really, overvolting leds a bit don't usually do much apart from shorter lifespan. overvolting a lot that usually kills it.

But yes, you can try with a multimeter to see before and after you start the car. its 11-12, before start, 13-14.5v after start engine and it runs the alternator.

dont test at the ciggy plug area, rarely you get full voltage unless its a new car.


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But dude, i know input is more than 12V.
But output, the voltage is 12v right, TO those electronics(air cond, lights)?

 

[shiroitenshi]

But dude, i know input is more than 12V.
But output, the voltage is 12v right, TO those electronics(air cond, lights)?

nope, most cars actually run fine with 14.5v, they were designed to, but they can also run with less voltage. Thats why I said if car, always calculate resistance required based on load using 14.5v

The battery is 12v. It only works to power the ecu, blower fan, lights, accessories, and the starter UNTIL the alternator takes over. The alternator will be the main source once engine starts, and the battery actually becomes a (consumer) or more accurately. a "load" on the electrical system in the car.

But this is also not 100% true that all accessories run 14.5v. Do remember that most car sensors runs on 5V, so your ecu does already have circuits to bring down the 12v/14.5v to 5v for the sensors. But never tap these wires for power, as the sensors use resistance/inductance/voltage to measure stuff, and you never ever want to simply add a load on its circuit.

Do understand that electronic do work in a "range" of voltages, not a single voltage. most auto specific electronics work up to 15v or 26V (for lorries)

You cannot consider voltage inductance and resistance in isolation as they are closely related.

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[punk]

That where a calculations of resistor needed.
Put a resistor that resist 4 volts.
Car: 12V
Needed: 9V

Why so hard?

----------------------------
This charger regualate to 9V 0.5A output.
Dont go simply buy any charger at supermarket and modify the connector because different output.

 

[stupidcar]

nope, most cars actually run fine with 14.5v, they were designed to, but they can also run with less voltage. Thats why I said if car, always calculate resistance required based on load using 14.5v

The battery is 12v. It only works to power the ecu, blower fan, lights, accessories, and the starter UNTIL the alternator takes over. The alternator will be the main source once engine starts, and the battery actually becomes a (consumer) or more accurately. a "load" on the electrical system in the car.

But this is also not 100% true that all accessories run 14.5v. Do remember that most car sensors runs on 5V, so your ecu does already have circuits to bring down the 12v/14.5v to 5v for the sensors. But never tap these wires for power, as the sensors use resistance/inductance/voltage to measure stuff, and you never ever want to simply add a load on its circuit.

Do understand that electronic do work in a "range" of voltages, not a single voltage. most auto specific electronics work up to 15v or 26V (for lorries)

You cannot consider voltage inductance and resistance in isolation as they are closely related.

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So when I actually tap those electronics wires, its 12V ma. NO?

---------- Post added at 02:58 PM ---------- 6 hour anti-bump limit - Previous post was at 02:58 PM ----------

Why so hard?

Hard weh. :hahaha:

 

[shiroitenshi]

So when I actually tap those electronics wires, its 12V ma. NO?

Yes, but only if engine is off/alternator not running.

Always estimate for 14.5V for car stuff since you run most stuff with the engine on.

Those 12V they put on amplifiers is to simplify things only, they already design for 14.5+V

but seriously since got adapter, the only reason you'd want to do mod to smart tag is to relocate the sensor somewhere. I plan to do, but so far cannot find spoiled unit i can crack open and see.

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[stupidcar]

Yes, but only if engine is off/alternator not running.

Always estimate for 14.5V for car stuff since you run most stuff with the engine on.

Those 12V they put on amplifiers is to simplify things only, they already design for 14.5+V

but seriously since got adapter, the only reason you'd want to do mod to smart tag is to relocate the sensor somewhere. I plan to do, but so far cannot find spoiled unit i can crack open and see.

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Really confused here.
My friends all said its okay. They have done their own lights.
Base on 12v as voltage source. Its fine.

Hmm, there are 2 things weh, can't really desolder it.
1 sensor another 1 i forgot what but both are important.

 

[punk]

Really confused here.
My friends all said its okay. They have done their own lights.
Base on 12v as voltage source. Its fine.

Hmm, there are 2 things weh, can't really desolder it.
1 sensor another 1 i forgot what but both are important.

i lagi confuse on what r u going to do .:hmmmm:

u wanna tap that 12V to the smart tag input?:vroam:

 

[stupidcar]

i lagi confuse on what r u going to do .:hmmmm:

u wanna tap that 12V to the smart tag input?:vroam:

For any electronics. we can tap it, just a resistor. Easy.

 

[shiroitenshi]

Really confused here.
My friends all said its okay. They have done their own lights.
Base on 12v as voltage source. Its fine.

Hmm, there are 2 things weh, can't really desolder it.
1 sensor another 1 i forgot what but both are important.

lights. are different, they have operating voltage range, they can use 12v - 24v. some bigger trucks use same lights bulbs but some of them run 24V+ , for leds, automotive types built in resistor, and overvolting them a bit is still no problem.

You're talking about a smart tag, which has sensitive components. They don't like being overvolted.

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[goohtj]

lights. are different, they have operating voltage range, they can use 12v - 24v. some bigger trucks use same lights bulbs but some of them run 24V+ , for leds, automotive types built in resistor, and overvolting them a bit is still no problem.

You're talking about a smart tag, which has sensitive components. They don't like being overvolted.

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simple solution
get a ic regulator lm7809 cost only <rm3
got 3 legs(connections) in, out, ground
just solder out -> red wire at s. tag
gnd-> black wire of s. tag (o volt or ground or car chassis)
in -> input or car battery

input range 10v ~ 30v and output is always 9v
can get the pin connections details online or pasar road sellet.
this is a simple diy..

 

[shiroitenshi]

thanks. i didn't know that ic solutions are available

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