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# Problem with current loss with increasing length of wire

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#### rajaram04

Hello
i am using a 12v 7Ah battery to run a motor with a fan attached to it. Problem is the decrease in speed or say load handling capacity when I am increasing the wire length. I need to run a 7 mtr length of wire but in 5 mtrs only I am facing the problem . . .Normal LED lamps are working at that end but motor is not working . just I feel a bit vibrations there . . I then connected low voltage motors but they are too not working like the original one . . how to overcome ??

#### betwixt

##### Super Moderator
Staff member
The only option is to use thicker wires I'm afraid. The voltage drop is caused by the resistance of the wire (Voltage drop = Current * Wire Resistance). As the voltage and current are fixed, you have to reduce the resistance by using heavier grade wires.

Brian.

#### KlausST

##### Super Moderator
Staff member
Hi,

You need to understand Ohm´s law.

V = R x I.

The voltage drop is: the wire_resistance x load_current.

Wire resistance is proportional to wire_length and indirect proportional to copper_cross_section.

Klaus

rajaram04

### rajaram04

Points: 2

#### wwfeldman

have you tried running the motor with the battery with 25 centimeters of wire?

you have specified the source (12V and 7Ah) what are the requirements of your motor?
nominal voltage and operating current?
start up current?
what gauge wire are you using?

what does "...just I feel a bit vibrations there..." mean?
is the motor vibrating?

you wrote "...I then connected low voltage motors but they are too not working like the original one..."
what voltage is the low voltage motor? what voltage is the original motor?

rajaram04

### rajaram04

Points: 2

#### rajaram04

The only option is to use thicker wires I'm afraid. The voltage drop is caused by the resistance of the wire (Voltage drop = Current * Wire Resistance). As the voltage and current are fixed, you have to reduce the resistance by using heavier grade wires.

Brian.

Ohh ok thanks . . here local shops provide wires on the basis of MM millimeter . . So what should I ask for in that case ? please guide

#### BigBoss

Ohh ok thanks . . here local shops provide wires on the basis of MM millimeter . . So what should I ask for in that case ? please guide
First, you should check the current consumption of the motor then search which copper area ( mm^2) should be used to prevent voltage drops across the cable.
There are tables in the internet that signify the effective copper area vs current consumption for grid voltage.

rajaram04

### rajaram04

Points: 2

#### Easy peasy

keep doubling up or tripling up the wires .....

rajaram04

### rajaram04

Points: 2

#### rajaram04

have you tried running the motor with the battery with 25 centimeters of wire?

you have specified the source (12V and 7Ah) what are the requirements of your motor?
nominal voltage and operating current?
start up current?
what gauge wire are you using?

what does "...just I feel a bit vibrations there..." mean?
is the motor vibrating?

you wrote "...I then connected low voltage motors but they are too not working like the original one..."
what voltage is the low voltage motor? what voltage is the original motor?

ya ya firstly it was working with I metre wire very efficiently. Even today I installed the motor in the vicinity of the power source and its working as usual.

and ya the motor seems like it's trying to rotate the shaft or say its try to work with the available parameters. But its too dull to detect.

i connected a 3v motor, a 5v DVD player motor, etc but no response & then also today i tried the same with a 5v relay and issues are again there . . .

- - - Updated - - -

keep doubling up or tripling up the wires .....

ya sure! ll try with that... thanks!

- - - Updated - - -

Hi,

You need to understand Ohm´s law.

V = R x I.

The voltage drop is: the wire_resistance x load_current.

Wire resistance is proportional to wire_length and indirect proportional to copper_cross_section.

Klaus

I see.... Ya as per that let me check the same . . thanks

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