Hi All,

I have a problem which may have a simple solution but I just wanted to make sure that I was going the right way.

I have a load which draws 40A of current at 48V. I am seting up battery banks which can provide power for 4 hours minimum. With all other factors, required battery capacity comes upto 388 Ahrs.

I have 4 batteries (48V, 150A) in series to form a bank/string.

So I will require minimum of 3 strings of batteries (450Ahrs) in pararllel to meet the requirement.

Now the question is....

For N+1 setup, can I just have 4 strings of batteries in parallel to full fill the required redundancy set up or will I need 6 strings in parallel (i.e. 3strings+3strings).

I am thinking its 6 strings but just wanted to make sure.

Hope someone could help me with this confusion.

Thank you in Advance.

Amar.


Battery Set up

|---------------0 Load 0----------------------|
| |
|---B1-----------B2--------B3--------B4----|
| |
|---B1-----------B2--------B3--------B4----|
| |
|---B1-----------B2--------B3--------B4----|
...........
......
...

Edited: 04 November 2010 at 01:16 PM by amarlama

If you are wanting redundancy to manage single fault condition, then you need only one more string of cells than required to meet normal use current requirements - the redundancy is to cover the case of any one cell (string of cells) going open-circuit.

So with 3 strings required by design (N = 3), you would need 4 (N+1) to comply with the redundancy requirement.

My initial thoughts were similar, its just I got the second thought of assuming N being 3 strings and for back up similar second set up hence requiring 6 strings.
But its making more sense to have 4 strings for N+1.. then 6 strings or else it would have been 2N setup..

Thanks for the help Paul.