Battery Capacity Calculator

This calculator will allow you to determine an appropriate battery size in Amp-hours given load, supplied voltage, duration, battery type and charge. 
Choosing the most appropriate battery for a circuit is a critical choice in designing a selected circuit. The type of battery also plays a crucial part in implementing this. 
CalculationInputs﻿﻿I 
:1.25 A​
﻿
﻿﻿t 
:20 hours​
﻿
﻿﻿Q
:50%​
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Outputs﻿﻿B (Lith) 
:40.201005​
﻿
﻿﻿B (Lead)
:25.13 A​
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⛔️ No Load Current Given... 
If the supplied load doesn't give a rated amperage, you can use the following calculation to manually determine the load current: 
Inputs﻿﻿Rated power, W
:5 W​
﻿
﻿﻿Rated voltage, V
:4 V​
﻿
Parameters
Output﻿﻿Rated current, A
:1.25 A​
﻿
﻿
I=PVdcI= \frac{P}{V_{dc}} I=Vdc​P​
ExplanationThe most important specification of a battery is its current rating. The rated capacity of any battery expresses the average amount of current it releases over a period of time under normal use. For example, a 4000Ah battery can deliver 100 A for 40 hours. 
The type of battery selected also plays an important role in battery size. Lead-acid batteries have a battery rating proportional to their discharge rate. 
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For lithium-ion batteries: 
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Bli−ion=100∗I∗t100−QB_{li-ion} =  \frac{100 \ast I \ast t}{100 - Q} Bli−ion​=100−Q100∗I∗t​
For lead-acid batteries:
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Blead−acid=100∗I∗t(100−Q)∗(0.02∗t+0.6)B_{lead-acid} =  \frac{100 \ast I \ast t}{(100 - Q) \ast (0.02 \ast t+0.6)} Blead−acid​=(100−Q)∗(0.02∗t+0.6)100∗I∗t​
Where: 
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B=Battery size (Ah)I=Load current (A)t=duration (h)Q=Remaining charge (%)B = Battery \: size \: (Ah)\\I = Load \: current \: (A) \\ t = duration \: (h) \\ Q = Remaining \: charge  \: (\%)B=Batterysize(Ah)I=Loadcurrent(A)t=duration(h)Q=Remainingcharge(%)
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