how to decrease current??

i have 12volt 8.5amps battery with me i want the output of 12v & 4amp 
i dont knw how plz anyone suggest me

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iceng2 months ago

You need to look and understand this kids cartoon...

Yonatan24 iceng2 months ago

I wish I saw this years ago... Saved :)

iceng2 months ago

How to measure ohms.

Set an appropriate multimeter to the ohms scale (the low cost units have 4 or 5).

Start with the lowest scale

A] Touch the Leeds together and verify meter reads zero..

B] Touch leeds across the load component and read the resistance.

C] If the meter reads - - then go to the next higher scale and repeat step [A]

D] Now you know the Voltage divided by the Resistance gives the Current that will flow !

Downunder35m2 months ago

Hmmm, my batteries only provide the current the load requires.
If the load is higher than what the battery can supply it wil be at the max the battery can provide.
Seems I am unable to understand your request because you don't (yet) understand how voltage and amps work together....

rickharris2 months ago

Just to add my little bit:

Current is drawn FROM a power source. As much as the load required (assuming a resistive load)

So to set the current of say an LED - which may require 20 milli amps of current but had a VERY low forward resistance you need to insert a suitable resistor in series with the LED to limit the current flowing to a safe amount.

If your load will only draw 12 volts at 4 amps that your OK. - the battery can supply more than that but all that will flow will be the current the load demands.

If you describe what your load is we may be able to be clearer.

seandogue2 months ago

The amount of current will depend on the load. If your load (the thing you want to power) requires 4.5 amps, you should be fine, although if your battery is an 8.5Ahr battery, it won't last all that long operating it.