Amp Hours and Watt Hours Explained in Solar Power Systems (Ah and Wh)
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🎁 Free diagrams: https://cleversolarpower.com/free-diagrams/
▶ Link to video about C-rate: https://youtu.be/3jYuIMuOhPU
📖 My best-selling book: https://cleversolarpower.com/off-grid-solar-power-simplified
When exploring the world of batteries, two terms often pop up: 'amp-hour' and 'watt-hours'. But what's the difference? Let's break it down.
First up, amp-hour.
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Amp-hour, abbreviated as 'Ah', is a measure of a battery's electrical storage capacity. It tells you how much current a battery can theoretically provide over a period of time.
You can have a 100Ah battery at 12V, a 100Ah battery at 24V or a server rack of 100Ah at 48V. All of these batteries have a different energy capacity. Now when someone asks how big your battery is, you shouldn’t say its 100Ah, because it depends on the voltage of the battery.
That’s why we will use Watt hours to accurately measure the energy capacity of a battery. Because Watt hour takes into account the voltage of the battery.
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Watt-hours, or 'Wh', represent the total energy a battery holds. It's the product of the battery's voltage and its capacity in amp-hours.
For instance, a 12V battery rated at 100Ah stores 1200 watt-hours of energy. While the 100Ah battery at 24Volts stores double that for a total of 2400 Watt hours. Or a 48Volt 100Ah battery that stores 4800Watt hours of energy.
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This watt hour rating gives a clearer picture of how long a battery can power a device. If a fan requires 100 watts to run, the 1200Wh battery can theoretically power this for 12 hours. Because 1200Wh/100W=12 hours. I say theoretically because a battery should never be discharged to 0%, whether it be lead-acid of lithium. Use 50% of the capacity for a lead-acid battery and 80% for a lithium-iron phosphate battery.
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In essence, amp-hours give insight into a battery's capacity, watt-hours reveal the total energy it can store. So why do we use Amp hours? This should be used to calculate the charge and discharge rate of a battery, also called C-rate.
The C-rate of a lithium battery is 1C while it is 0.2C for a lead-acid battery. Knowing this, we can calculate the maximum charge and discharge current for the battery under normal conditions.
For example a 100Ah lithium battery can provide a current of 100Amps. while a lead-acid battery can only provide a current of 20Amps. A battery can provide more current, but that will decrease it’s lifespan because the cells will degrade faster.
I talk more about C-rate in my dedicated video about it. There will be a link in the description.
________________________________________
Did you like this explanation? Give it a thumbs up, and subscribe for more off-grid solar tutorials. Do you have video suggestions? Let me know in the comments and I will make a video about it.
And before you go! If you're interested in off-grid solar power, I'm giving away 7 different diagrams that you can use for your projects. These diagrams are designed to help you set up your solar system efficiently.
All you have to do is click the link below, provide your email, and I'll send them your way.
00:00 Introduction
00:10 Amp Hours
01:10 Watt hours
01:48 Charge/Discharge time
02:35 Why use Ah?
03:41 Outro
▶ Link to video about C-rate: https://youtu.be/3jYuIMuOhPU
📖 My best-selling book: https://cleversolarpower.com/off-grid-solar-power-simplified
When exploring the world of batteries, two terms often pop up: 'amp-hour' and 'watt-hours'. But what's the difference? Let's break it down.
First up, amp-hour.
________________________________________
Amp-hour, abbreviated as 'Ah', is a measure of a battery's electrical storage capacity. It tells you how much current a battery can theoretically provide over a period of time.
You can have a 100Ah battery at 12V, a 100Ah battery at 24V or a server rack of 100Ah at 48V. All of these batteries have a different energy capacity. Now when someone asks how big your battery is, you shouldn’t say its 100Ah, because it depends on the voltage of the battery.
That’s why we will use Watt hours to accurately measure the energy capacity of a battery. Because Watt hour takes into account the voltage of the battery.
________________________________________
Watt-hours, or 'Wh', represent the total energy a battery holds. It's the product of the battery's voltage and its capacity in amp-hours.
For instance, a 12V battery rated at 100Ah stores 1200 watt-hours of energy. While the 100Ah battery at 24Volts stores double that for a total of 2400 Watt hours. Or a 48Volt 100Ah battery that stores 4800Watt hours of energy.
________________________________________
This watt hour rating gives a clearer picture of how long a battery can power a device. If a fan requires 100 watts to run, the 1200Wh battery can theoretically power this for 12 hours. Because 1200Wh/100W=12 hours. I say theoretically because a battery should never be discharged to 0%, whether it be lead-acid of lithium. Use 50% of the capacity for a lead-acid battery and 80% for a lithium-iron phosphate battery.
________________________________________
In essence, amp-hours give insight into a battery's capacity, watt-hours reveal the total energy it can store. So why do we use Amp hours? This should be used to calculate the charge and discharge rate of a battery, also called C-rate.
The C-rate of a lithium battery is 1C while it is 0.2C for a lead-acid battery. Knowing this, we can calculate the maximum charge and discharge current for the battery under normal conditions.
For example a 100Ah lithium battery can provide a current of 100Amps. while a lead-acid battery can only provide a current of 20Amps. A battery can provide more current, but that will decrease it’s lifespan because the cells will degrade faster.
I talk more about C-rate in my dedicated video about it. There will be a link in the description.
________________________________________
Did you like this explanation? Give it a thumbs up, and subscribe for more off-grid solar tutorials. Do you have video suggestions? Let me know in the comments and I will make a video about it.
And before you go! If you're interested in off-grid solar power, I'm giving away 7 different diagrams that you can use for your projects. These diagrams are designed to help you set up your solar system efficiently.
All you have to do is click the link below, provide your email, and I'll send them your way.
00:00 Introduction
00:10 Amp Hours
01:10 Watt hours
01:48 Charge/Discharge time
02:35 Why use Ah?
03:41 Outro
