I was working over the topic Battery management system where now I have encountered a problem due to lack of proper knowledge in this field.
My Problem statement is to achieve an uninterrupted power supply to my load using switching between batteries at proper time.
Find the attachment below,this will give the basic circuit diagram(only a part of PS)
where only I am facing problem
My key concept is that first I will extract power for the load from first battery while tracking its STATE OF CHARGE(SOC).At this point of time by second battery that is backup battery will remain

disconnected.But when the SOC of first battery will swoop down to 10% I will shift the backup battery to the supply(Using a micro controller and power relay).I have TWO OPTIONS:
1st Option:I will only shift the backup battery to supply and wont remove the firs battery from supply.That will stay connected.
2nd Option:I will shift the backup battery to power supply and later after few seconds will remove the first battery from supply line.
I know my PS will be achieved but I don't know the disadvantage that will take place later.
For example,I know that when 1st option will be followed ,charging of first battery will take place simultaneously.Will that create any problem to the power supply to my load?What will be the Outcome for the First battery?
Thanking you in anticipation!!!

 

what attachment...?

 

Details, details, details.

What is the voltage and capacity of each battery?
What is the load current?
Why do you want to switch out batteries? It is common practice to connect batteries in parallel.

 

yeah...actually the battery that I will be shifting will be backup battery which will be used only when I will specify(that is when my first battery goes to 10% SOC).moreover,The Same backup battery is used at different parts of my whole power system whenever needed.That is my power system consists of 4-5 power independent circuits where I am giving power to each of them through separate battery,and whenever any of these battery will drain the backup battery will shift there and provide power
Each battery used is 26Ah and 12V.My

what attachment...?