Wire size consideration.

Hi, i am working on a circuit that is used to measure the battery's voltage. The battery is rated at 12V,100Ah. The 100Ah should be the supported load current by the battery right?

Another question is can i use normal size jumper wires or do i need to go for thicker wires? What is the difference if i use thicker wires for the circuit compared to normal wires? ( The wires will first be used on breadboard(testing) and if is working fine, it will be used in veroboard to make point to point connections).

Would thicker wires damage the components due to its wire width?(Just assuming).

Should i use thicker or normal wires just to be in safe side?

Thanks.

The size of wire you choose will be dictated by the amount of current through the wire.
The current will depend on the load (resistance) drawn by the measuring device.
A typical voltmeter presents a load resistance of 10MΩ.
At 12V the current is 1.2μA. The smallest gauge wire you can find would still work at this current.

MrChips said:

The size of wire you choose will be dictated by the amount of current through the wire.
The current will depend on the load (resistance) drawn by the measuring device.
A typical voltmeter presents a load resistance of 10MΩ.
At 12V the current is 1.2μA. The smallest gauge wire you can find would still work at this current.

Click to expand...

Thanks for the answer. I have another circuit which i need to find out what is the suitable wire size. Its basically a timer circuit operated by a thermistor and the timer will drive a 12V relay to run a water pump.

The load is a small 12vdc water pump. Lets assume if the pump's load current is 1A. Can normal wire handle this current value?

Just use some 20 to 24 AWG wire for 1 Amp

24 AVG will work, for higher currents use this chart:

@ Mrchips, There is no chart attached!

100ah has nothing to do with the maximum amps that can flow from the battery, it only tells you the product of amps and time without reference to the time. It may be 1 amp for 100 hours ; .01 amps for 10000 hours or even; 10 amps for 10 hours are all possible depending on the chemistry or design of the battery. Look for a C rating on the battery. For example, a C10 rating means max current can be 10x the capacity (numbers this high are usually only on lithium polymer batteries). On the other hand, a C/10 rating means 0.1x the capacity. Some batteries, like watch batteries will have extremely low discharge rates.

mrmount said:

@ Mrchips, There is no chart attached!

Click to expand...

There is something strange with .jpg files that I upload to AAC albums and post. People claim not to be able to see them. I and others can see them.
What OS and browser are you using?

Expanding on Gopher's post (#7)

A car battery might be rated at 12V, 100 amp hours, and throw 350 amps through the starter motor for a few seconds. Repeating, 100 AH means almost nothing about the maximum amps that the wire must carry.

and yes, I can see the chart with Firefox as my browser.

.jpg does NOT show up on iPad but does show up on Internet Explorer (Windows 7)