Question

Take four 12VDC/7.5AH lead acid batteries. How different associations of these batteries affect the power? What’s the key on defining the best arrangement?
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Answer 1

Before finding which configuration of battery arrangements is better, we need to learn some important thing about battery voltage and Amper hour rating. 12 v and 7.5AH rating it means that 12 v can supply 7.5A of current for 1 hour after that battery will be discharge. This battery can run for half hours if current drawn from battery is 15A. Now suppose we have 24 v 7.5 AH battery, again it will draw 7.5 A current for 1 hour and 15 A current for half hour. If we use 48 v battery with 7.5 AH then it will draw 7.5 A current for 1 hour and 15 A current for half an hour. Then why battery voltage is important?? Because if we use higher voltage rating battery then it will provide more power to perform work, though it will draw same current but it will give high capacity to do work without damaging battery.

Now come to our point, we have three configuration in series we are getting 4 times voltage but AH will be same, in parallel configuration voltage will be 12 v while AH will increase to 30 AH. And in series parallel configuration, we are getting 24v and 15AH current rating. In series configuration voltage is more which will give you more power to work better but it will draw only 7.5 A current for an hour. In parallel configuration, voltage is 12v but it gives you 30A current for an hour but it will not give you power to work with an efficient means battery life will degraded. But if we consider series parallel configuration then we can see that it gives us 24 v and 15AH which is better in both current rating as well as voltage rating, it gives you better current rating per hour and capable to provide power to do work very well. Again we must note that these configuration have their own use. If we want to perform some taks which needs longer life of charging then we can uses parallel configuration where we can run 4 hours with 7.5 A current flow.

But if we want overall things then series parallel combination is good option.

Note- please find me in comment box if you find any difficulty. I tried to give you total clarty of how voltage and current rating works and which is useful. Good luck.