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What is a 200Ah battery? [for beginner]

Updated: Mar 28

Have you ever find yourself confused, while searching the purchasing 200Ah battery over the internet and there is no one in front of you to explain what it means by 200Ah battery and how much power can be stored in it.


If you take your search one step further you will find that there two different voltages (12V and 24V) of 200Ah battery available and this will further confuse you. Do you know there are also two class of 200Ah batteries available that is class 10 and 20?


In this blog, I will give definitions of 200Ah battery and some in-depth details on how much backup it can provide as well as what is the difference between C10 and C20 battery.


Before jump into the details of a 200Ah battery, here is an explanation of


What means by a 200Ah battery?.


200Ah is mean that battery is guaranteed to provide a continuous current of 20A over the discharge period of 10 hours (20A x 10h =200Ah) if the battery is of Class C10 and if it is of Class C20 it will provide a continuous current of 10A over the discharge period of 20 hours (10A x 20h =200Ah).


Content table

Definition of a 200Ah battery


Generally, there are only two details you will find on the sticker of the battery other than warranty, that is the battery voltage (‘V’) and battery rating (in ‘Ah’).


Where Ah or Ampere/hour capacity is current a battery can provide over a specified period of time to a specific End of discharge Voltage at a specific temperature. Whereas End of discharge Voltage is the level to which the cell voltage is allowed to fall to before affecting the load.

As the battery starts discharging, the voltage across its terminals starts reducing too but the rate of voltage drop throughout the discharging period is not too much high.
The voltage battery provides before it fails is called End of discharge Voltage.

Also, the battery voltage is the nominal voltage across battery terminals. Generally, the battery voltage for a 200Ah battery is 12V or 24V.


A 12V, 200Ah battery is the most common battery available in the market over the globe and it is made of 6 numbers of 2 V cells with End of discharge Voltage per cell is varied from 1.75 V to 1.8 V. Hence the End of discharge voltage for 12V battery varies from 10.5V (1.75x6) to 10.8V (1.8x6).


[Lead acid cells generally produce an electrical potential of 2V while Nickel-cadmium cells generally produce an electrical potential of 1.2V]

If you try to find the details of “End of discharge Voltage” for the battery on its sticker, you won’t find the same. To get the same you need to ask for the battery specification from the battery retailer or you can download the same from the manufacturer’s website.


Following is an example of battery specification I found on the internet, you may found a completely different format of specification because there is no such standard for the same.


As per the above specification of battery, the capacity of the battery is defined as 200Ah at a 10-hour rate to EOD of 1.8V per cell at 25 Degree Celsius. As you can see, the number of cells is also defined in the above specification, which is ‘6’.


This means that this 12V, 200Ah battery is guaranteed to provide a continuous current of 20A over the completely discharge period of 10 hours (that is 20 Ampere x 10 Hour=200 Ah) and the end of discharge voltage of the battery will be 10.8V (6 x 1.8V per cell) at 25 Degree Celsius.


Difference between C10 and C20 200 Ah Battery


In some specification, you will find that capacity of the battery is mention as 200Ah at a rate of C10. Where ‘C10’ refers to the guaranteed performance of the battery for 10-hour. Similarly, for the ‘C20’ battery, the battery is guaranteed for the performance of 20-hour.


But in both case the Ampere-hour of the battery remains the same, that is for the 200Ah Class C10 battery, the battery is guaranteed to deliver a continuous current of 20A for 10 hours. Hence the Ampere-Hour of C10 will be equal to 20A x 10H = 200Ah.


Also for the 200Ah Class C20 battery, the battery is guaranteed to deliver a continuous current of 10A for 20 hours. Hence the Ampere-Hour of C20 will be equal to 10A x 20H = 200Ah.


But if we compare the discharge ampere of C10 200Ah and C20 200Ah battery we will find that 200Ah C10 battery can deliver 10.3A of continuous current which is slightly higher than 10A of 200Ah C20 for the same discharge period.


But 200Ah C20 battery can deliver 18.3A of current over the discharge period of 10 Hour which is lower than the 20A of 200Ah C20 battery for the same discharge period.

Table-1


Table-1 shows the difference between the discharge current of 200Ah C10 and 200Ah C20 battery with identical EODV (End of Discharge Voltage)


Difference between 12V 200Ah battery and 24V 200Ah battery


The difference between a 12V and a 24V 200AH battery is the voltage across their terminal and the power store in them.


In electricity, the formula of power is, Power = Voltage x current


Hence the amount of power store in a 24V, 200Ah battery will be 24V x 200 Ah = 4800 Watt-hour (4.8kWh).


And the amount of power store in a 12V, 200Ah battery will be 12V x 200Ah = 2400Watt-hour (2.4kWh).

This means that for a similar load 24V, 200Ah battery will give twice the backup time as compared to 12V, 200Ah. And for similar backup time 24V, 200Ah battery can run twice the load as compared to 12V, 200AH.

Refer to the below table for a better understanding of the comparison between the power store in 12V 200AH and 24V, 200 Ah batteries.


Before jump to a conclusion that a 24V battery is better than 12V after a comparison of price and power store in them. You need to understand that to charge as well as extracting power from a 24V battery you will require a 24V inverter too. And the price of a 24V inverter is higher than that of 12V.


Also, you cant charge a 24V battery from a 12V inverter, but you can charge two 12V battery (after connecting them in series) from a 24V inverter.


There are other reasons like availability of 24V battery as well as 24V inverter is very low as compare of 12V battery and inverter. Makes going with a 24V battery instead a 12V battery could be a bad decision.


How long will a 200 ah battery last?


The backup time of the 200Ah battery depends upon the discharge rate of the battery. That is, the backup time of the 12V, 200Ah C10 battery will be different from the C20 battery.


Let us compare the backup time of the C10 and C20 battery


Backup Time fo C10 battery:


Refer below table you can see the discharge rate of 12V, 200Ah at 10-hour rate to EOD of 1.8V per cell at 25 Degree Celsius


From the above table, you can see that 12, 200AH C10 (at 10Hour rate) gives only 118A x1 = 118Ah (1398 Watt of Power for 1 Hour) if you completely discharge it within 1-hours. But if you completely discharge it in 20 Hours battery will give 20A x 10 = 200Ah (118 Watt of Power for 20 Hours)


Due to the efficiency of the inverter (which is 90% to 95% for a high-end sine wave inverter) the AC output power will be 5% to 10% lesser than the battery output.


Backup Time fo C20 battery:


Refer below table you can see the discharge rate of 12V, 200Ah at 20-hour rate to EOD of 1.8V per cell at 25 Degree Celsius

From the above table, you can see that 12, 200AH C20 (at 10Hour rate) gives only 93.68A x1Hour = 93.6Ah (1087.8 Watt of Power for 1 Hour) if you completely discharge it within 1-hours.


But if you completely discharge it in 20 Hours battery will give 10A x 20= 200Ah (114 Watt of Power for 20 Hours)


Comparison between the backup time of 200Ah C10 and 200Ah C20 Battery


Refer to the below table, which shows the comparison between backup time for C10 and C20 battery of the same Ampere hour (200Ah), End of Discharge Voltage (1.8V) and terminal voltage (12V).


From the above table, it is clear that C10 batteries provide much more backup time than C20 batteries. And that's the reasons why C10 batteries are more preferable to C20 batteries, especially for off-grid solar power plants.


In off-grid solar power plants, you have only 5 to 7 hours of sunshine to charge your batteries and the remaining 17 to 19 hours of power will be provided by batteries.

If you are interested to learn how much solar panels are required to charge 200Ah of batteries in sunshine of 5 hours. I highly recommend you to read my blog on the same. Click here to read the blog.

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