[Galaxy 3 General] nrk_2k:
No, we are not of the same opinion, I say the percentage of a batteries voltage used has nothing to do with how quickly it is discharged, it is all dependent on the current being drawn from the battery. If both batteries have the same mAh rating then both batteries will last the same amount of time. The mAh rating on a battery shows how many mA it is capable of producing over a 1 hour period, taking the battery from fully charged to fully discharged, regardless of the load attached to the battery or percentage of the batteries voltage used. If you draw more than this amount, it will last less than an hour till fully discharged, or if you draw less, it will last longer than an hour.

By no way, shape, or form can Voltage EVER be changed into Amperage, this is totally impossible!!! Current is the flow of electrons through a conductor, voltage is the potential difference between the positive and negative terminals of the battery. It is physically impossible to convert a difference between electrical charge into a flow of electrons outside the battery, or inside the battery. Yes V=IR, but when V is changed, the change in I is not from converting the voltage, it comes from a change in current draw from the battery. The only time you can increase amperage in a circuit while also causing the reduction of voltage is using a transformer in an AC circuit, and this doesn't convert voltage into amperage, it's a conversion of electrical energy into magnetic energy then back again with a different ratio. The Wh of a battery is calculated at no load, I never said that it changes. I'll use the below example to try and explain things.

e.g. If you have two very basic circuits each with a battery, 2 wires and a resistor. Both circuits use the same 10v, 1000mAh batteries, but the first circuit has a 10ohm resistor, and the second has a 1ohm resistor. Using these figures we are able to calculate the current drawn from the circuit, and therefore the watts used by the resistor, and then from there the Wh consumed by the resistor.

Circuit 1, 10ohm resistor:

V = 10

R = 10

Ah = 1

therefore V=IR, or I=V/R, I=10/10, I=1A

Battery Watt-hour Wh=V*Ah, Wh=10*1, Wh=10Wh

Resistor power consumption P=V*I, P=10*1, P=10W

In this case, the battery would last 1 hour, as the battery has a rating of 1Ah (1000mAh) and the circuit draws 1A

Circuit 2, 1ohm resistor:

V=10

R=1

Ah = 1

therefore V=IR, or I=V/R, I=10/1, I=10A

Battery Watt-hour Wh=V*Ah, Wh=10*1, Wh=10Wh

Resistor power consumption P=V*I, P=10*10, P=100W

In this case, the battery would last 6 minutes, as the battery has a rating of 1Ah (1000mAh) but the circuit is drawing 10A so the battery will only last 1 tenth of an hour (6 mins).

Now in the above simple examples, you could use Wh just as easily to measure battery capacity, even though it requires a little more calculation, but once you step outside these basic examples into real world examples, using Wh as a measure of battery capacity becomes a LOT more complex, where as Ah remains arbitrarly easy to calculate, as components usually have their current draw listed/known so total maximum current draw can be easily calculated (where as a wattage listed on the component cannot be easily added, as the component may require lower voltage than the batteries total, so the wattage draw from the battery may be different). As with real world circuits, you introduce capacitors, inductors, voltage regulators, oscillators, transistors, negative/positive feedback loops, internal battery resistance (which does not affect battery output, but does affect total circuit resistance, this is very complex to explain face to face, let alone on a forum, so i won't try), series-parallel subcircuits, and the list goes on. This is why Wh is not used as a measure of battery capacity.

sharukins, I have been professionally trained in electrical engineering, so my knowledge has come from worldwide industry standard training, and real world practical experience, I have internationally recognised qualifications, so you are not just arguing against me, but the entire worldwide electrical community :D there is a lot of information out there on various different websites, I know, I have had a look through some of it (unfortunately a lot of what I have read online takes either too basic a look at things, and provides reasoning which just doesn't match up with the real world, or fails to explain things properly. So I can understand that if this is where you got your understanding, why you may find the information I have provided as being contradictory. I hope that our discussion on this forum post has taught others something they didn't previously know, or even ecourages others to seek education or a career in the field as it is a very rewarding field to be in :D