Summary of How to make Automatic Charger for a 7Ah Battery
This article explains the characteristics of 7Ah sealed lead-acid batteries, ideal for medium-power devices like fans and LEDs. It details the charging requirements, specifying a source voltage of 14.4V (20% higher than the 12V battery) to prevent overcharging. The text describes how constant voltage sources allow batteries to draw only the current they need, ensuring safety and longevity without manual cutoff.
Parts used in the 7Ah Sealed Lead Acid Battery Charger:
- 7Ah Sealed Lead Acid Battery
- 14.4 Volt Charging Source
- Automatic Charger Circuit
7Ah Sealed Lead Acid Battery
7Ah Sealed lead acid battery is a very popular battery which people use in most places like fans, LEDs etc. The reason behind popularity of 7Ah battery is due to its medium size and medium Ah rating. By medium means, its size and ratings lies between the small batteries and large batteries. For medium purposes, the size and rating of battery is ideal.
For example if you want to glow a 20Watt LED then this battery will serves the purpose really well.Before go further, studying the articles related to battery basics, rechargeable batteries and non- rechargeable batteries would be fruitful. Here we will design a 7 Ah charger for this battery.
For example if you want to glow a 20Watt LED then this battery will serves the purpose really well.Before go further, studying the articles related to battery basics, rechargeable batteries and non- rechargeable batteries would be fruitful. Here we will design a 7 Ah charger for this battery.
How to Charge a Battery
You probably already listened that to charge a battery the voltage of charging source should be greater than the battery voltage but the question is how much voltage should be greater and when will I know that you should stop charging now?
There are two questions here. Let’s answer it one by one.
Want to buy a 12 volt battery charger? Click on the image below:
How much source voltage should be greater than the battery voltage to charge?
It’s not a single value that you can rely on. But an average value at which you can surely charge your battery without hesitation is 20% more voltage than the battery voltage.
To charge a 12 volt battery the charging source should be 14.4 volts. Now the question is that how to attain this volts. I will answer this question later.
When Should you Stop Charging?
During building a charger, the most important question comes in mind that when should I cut off the charging source. This is the very critical point during making automatic chargers because mostly batteries do not bear overcharging and their life drastically decreases due to overcharging. Before I answer this question first understand anot should be charge at C/10 current no matter how big the battery is.
Here, C=Ah
Which means if you have 100Ah lead acid battery then its charging current must not be greater than 100/10=10 A. So the question is how to maintain 10 A current going inwards the battery? The answer is that the internal resistance of ‘12 volts 100Ah lead acid batteries’ is adjusted in such a way that whenever you apply the voltage of 14.4 volts then the battery will automatically draw 10 Amps.
Now our question was that when should you stop the charging? You don’t have to!! If you are able to apply the constant voltage source of 14.4 volts than the battery will draw current from the source according to its need.
For example in 100Ah battery, if the battery is fully discharged then it will take 10Amps from the 14.4 volts source and if the battery is fully charged then it will not draw any current from the source and at 50% charging it will draw 5amps from source.
Now I think you are able to understand the procedure of making an automatic charger for sealed lead acid batteries. You can apply this procedure for any sealed lead acid battery but the charging source should be big enough to give the required current to the battery.
Read More: How to make Automatic Charger for a 7Ah Battery
Read More: How to make Automatic Charger for a 7Ah Battery
- Why is the 7Ah battery popular?
It has a medium size and rating that lies between small and large batteries, making it ideal for medium purposes. - How much should the charging source voltage be greater than the battery voltage?
The average value is 20% more voltage than the battery voltage. - What voltage is required to charge a 12 volt battery?
A charging source of 14.4 volts is needed. - When should you stop charging a sealed lead acid battery?
You do not have to manually stop if you apply a constant voltage source of 14.4 volts as the battery draws current according to its need. - What happens if a battery is overcharged?
Batteries do not bear overcharging well and their life drastically decreases due to it. - How is the charging current determined for a lead acid battery?
The charging current must not be greater than C/10, where C equals the Ah rating. - Does the battery draw different currents based on its charge level?
Yes, a fully discharged battery draws maximum current while a fully charged one draws no current from the source. - Can this charging procedure be used for other sealed lead acid batteries?
Yes, you can apply this procedure for any sealed lead acid battery provided the source is big enough.
