# supply power -Can a Nicd battery supply 20 amps to a coil?

#### minh

Joined Nov 24, 2010
41
Dear all
Please help me to know: 14.4V Nicd Battery, 1.7Ah can full supply ( to an coil) 20 amps in 20 millisecond (other problem( issues )don't care) Many thank you

#### crutschow

Joined Mar 14, 2008
34,697
14.4V Nicd Battery, 1.7Ah can full supply ( to an coil) 20 amps in 20 millisecond
How often do you need to generate this pulse?
The batteries internal resistance may prevent supplying 20A, but a large capacitor charged by the battery could.

#### MisterBill2

Joined Jan 23, 2018
19,034
If there are no intermediate fuses or protection devices, YES, the battery can probably deliver 20 amps for a few seconds, if it is charged and in good condition.

#### WBahn

Joined Mar 31, 2012
30,251
Dear all
Please help me to know: 14.4V Nicd Battery, 1.7Ah can full supply ( to an coil) 20 amps in 20 millisecond (other problem( issues )don't care) Many thank you
How big is the coil? What is the winding resistance?

Those two things alone might make it impossible for even an ideal 14.4 V source to get you to 20 A in 20 ms.

#### BobTPH

Joined Jun 5, 2013
9,174
Don’ forget the inductance.

dI / dt = V / L

20 / 0.02 = 14.4 / L

L = 14.4 x 0.02 / 20 = 0.014

So the coil can have at most 14mH inductance. That is if it has zero resistance.

#### minh

Joined Nov 24, 2010
41
How often do you need to generate this pulse?
The batteries internal resistance may prevent supplying 20A, but a large capacitor charged by the battery could.
How big is the coil? What is the winding resistance?

Those two things alone might make it impossible for even an ideal 14.4 V source to get you to 20 A in 20 ms.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
Don’ forget the inductance.

dI / dt = V / L

20 / 0.02 = 14.4 / L

L = 14.4 x 0.02 / 20 = 0.014

So the coil can have at most 14mH inductance. That is if it has zero resistance.
Many thank you for your help
Don’ forget the inductance.

dI / dt = V / L

20 / 0.02 = 14.4 / L

L = 14.4 x 0.02 / 20 = 0.014

So the coil can have at most 14mH inductance. That is if it has zero resistance.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
How often do you need to generate this pulse?
The batteries internal resistance may prevent supplying 20A, but a large capacitor charged by the battery could.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
Don’ forget the inductance.

dI / dt = V / L

20 / 0.02 = 14.4 / L

L = 14.4 x 0.02 / 20 = 0.014

So the coil can have at most 14mH inductance. That is if it has zero resistance.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
Don’ forget the inductance.

dI / dt = V / L

20 / 0.02 = 14.4 / L

L = 14.4 x 0.02 / 20 = 0.014

So the coil can have at most 14mH inductance. That is if it has zero resistance.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
If there are no intermediate fuses or protection devices, YES, the battery can probably deliver 20 amps for a few seconds, if it is charged and in good condition.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
How often do you need to generate this pulse?
The batteries internal resistance may prevent supplying 20A, but a large capacitor charged by the battery could.
Many thank you for your help

#### minh

Joined Nov 24, 2010
41
How often do you need to generate this pulse?
The batteries internal resistance may prevent supplying 20A, but a large capacitor charged by the battery could.
How often do you need to generate this pulse?
The batteries internal resistance may prevent supplying 20A, but a large capacitor charged by the battery could.
Many thank you for your help

#### BobTPH

Joined Jun 5, 2013
9,174
One thank you is enough!