# Is it possible to add 5s battery pack to 10s lithium battery pack

Hi

I am building 10s6p battery pack with 18650 cells from old laptops.

I have read somewhere that if additional cells added at the end of battery pack it will increase capacity and performance.

My question is;

What happenes if we build a battery pack with 5s6p+(5s6p+5s6p) Total pack will be 10s.

The reason for this is to merge and use capacity of weak and unstable cells instead of throwing them away.

Thank you.

It is a very bad idea to mix good and bad cells. You will destroy the entire pack that way.

Thank you Jremington.

Is this (5s+5s+5s) combination possible if all cells are good?

Of course that will "work", but how do you plan to balance the charging?

Perhaps I don't understand what you mean by + or "at the end" but I can't think of any practical combination of 3 x 5S packs that will end up as 10S. How EXACTLY are thinking of connecting them?

In my world 5S+5S+5S will always be 15S unless + means "in parallel" in which case it will be 5S.

Steve

PHOTOGUY: The reason for this is to merge and use capacity of weak and unstable cells instead of throwing them away.

Your really building a battery pack with unstable cells ?

Where does the Arduino get used in this unstable power pack ?

Ever seen a LiPo explode ?

PHOTOGUY: Hi

I am building 10s6p battery pack with 18650 cells from old laptops.

Series packs must use identical cells, and you must use a balancing charger... Get this wrong with lithium cells are you'll risk starting a fire.

I have read somewhere that if additional cells added at the end of battery pack it will increase capacity and performance.

Sounds like nonsense to me. You can produce a higher voltage, but not capacity or performance, thats a property of the weakest cell in the chain (and as mentioned above, you don't want any weak cells in the chain).

My question is;

What happenes if we build a battery pack with 5s6p+(5s6p+5s6p) Total pack will be 10s.

Clearly 5S is series with 10S is 15S, but you've broken the essential rule of building batteries of cells, everything must be matched.

The reason for this is to merge and use capacity of weak and unstable cells instead of throwing them away.

Not with lithium you don't, that is flipping dangerous

Thank you.

Sorry for not explaining combination of battery properly;

Ok we have 5s+5s=10s battery pack.

We will add one more 5s parralel to 2nd 5s pack.

It will be 5s6p+5s*12p*

I will use diode for this additional pack to make sure it will only give power not consume the power.

I have balance charger to balance each individual cell.

Is it ok like this?

No.

PHOTOGUY: Sorry for not explaining combination of battery properly;

Ok we have 5s+5s=10s battery pack.

We will add one more 5s parralel to 2nd 5s pack.

It will be 5s6p+5s*12p*

i don't understand how it will end up looking - can you just DRAW it ?! (how does the 6p and 12p suddenly come into it ??)

you really should forget about "mixing and matching" Lithium-ion batteries because they are a very "special kind of breed" that needs specific handling - you can't just add and "boost" and "help along" like other more common (consumer) batteries by connecting in series and parallel.

just stop what you are trying to do with "old" batteries unless they were a single pack to begin with.