Blue Wire Laptop Charger.. Help!

[Moh001]

i have laptop charger caple with three wires black blue white, i cut off the blue one and use the black and white to charge the laptop from 12v acid battery using boost converter 19.5v, the problem is the current is too high 3 to 4 amps!!! how can i reduce the current to 0.5 amp??? the blue wire for information i dont know how to use it with the boost converter.. when adding resisors the charging stops i think due to voltage drop.. help!

 

[(*steve*)]

Which current is to high? 2A to 3A to a laptop while charging it's battery seems reasonable. With the boost converter that could easily be 3A to 4A or even higher.

If you remove the laptop's battery the current may be lower.

 

[Audioguru]

The laptop or its battery has either a circuit to measure charging current then feed a signal on the blue wire to reduce the charger current or the blue wire connects to a thermistor in the battery that feeds the charger to tell it to reduce the current because the battery is getting too hot. That is why you should always use a charger that is designed for the product.

 

[Moh001]

Which current is to high? 2A to 3A to a laptop while charging it's battery seems reasonable. With the boost converter that could easily be 3A to 4A or even higher.

If you remove the laptop's battery the current may be lower.

when i measure the Amp whith the AC Adapter the current is 0.5 amp so i assume 3 amps is high, the boost converter gets very hot and even starts to smoke, i want the current to be 0.5 to 1, how?

 

[Moh001]

The laptop or its battery has either a circuit to measure charging current then feed a signal on the blue wire to reduce the charger current or the blue wire connects to a thermistor in the battery that feeds the charger to tell it to reduce the current because the battery is getting too hot. That is why you should always use a charger that is designed for the product.

thank you,but i want to use acid battery to charge it, do you know how? i just know boost converter circuit but i have problem with current as u see

 

[davenn]

you already have another thread on this subject

this thread is closed