# Lithium ion battery pack anatomy

Does the anatomy of this battery pack make sense ?

Its meant to be 8 in series and 4 in parallel.

I don’t think I got the 4 in parallel right ?

Also do you guys know what type of wires I need to buy for this, I have already bought a nickel/battery tab machine and the lithium ions (samsung) but I don’t know which wires to pick?

looks good.

your scheme is not incorrect, but in your case you need to balance 32 cells and in “normal” 8s4p - only 8

Not sure what you mean, but I’m gonna have a BMS to balance cells. I have created another one but I do not know which is correct.

Right now Im just designing the basic anatomy of the battery cells so I do not do anything wrong.

What do you think of this one?

This gives me an idea for a modular type battery pack. I am very new to building packs and know very little about it so Im not sure if this will work at all but here goes. What if instead of soldering the packs in parallel, you took the positive lead and the negative lead and put them into and XT60/XT90 connector. Then did the same for each pack and connected them. This would be useful if you were flying and needed to break them down into smaller <99 WH packs (83.7=29.6) (29.63=88.8 WH) I was assuming a 3000mah cell for that last equation. Here is a digram that represents what I am saying.

U have 4 rows of 8 cells in series. Each cell is individual in this way. If u putt four in parallel…and then put that four in series with 4 in parallel etc. …then the parallel four cells will be working together as one and ull only need one balance wire for those 4

Im curious about these diagrams as well as I am trying to learn as much as possible about building your own pack. Would you point me in the direction of a diagram fro a compact or flat 10s3p 10s4p, or 8s4p? Preferably one that is easy to understand for a beginner in the field like me.

your second is the same as the first

“normal” sheme:

I am using 18650 samsung 3.7v with 2500mah each.

So my question is once I add a BMS will the first battery diagram post I made earlier work as a 8s4p battery pack making 8 series = 29.6 volts and 4 parallel = 10,000 mah in total??

Sorry guys I’m bit of an amateur at this, don’t know what “normal” sheme means?

the first you posted will make it very difficult to add a bms as while it’s said the cells are in parallel, they really aren’t and instead it’s 4 strings of cells in parallel. you want to put them in parallel so they are effectively one battery when in parallel. yes you’ll have 10ah either way but it’s about being able to add a bms. the last pic above the cells are grouped in parallel so they behave as one cell and you could add a bms volt sensor to one and they willl all show the same…as they’re truly in parallel normal scheme

@hummie

I made a new layout what do you think?

The green is the nickel strip and I know once I add the BMS i will have to attach each of the 8 wires to each 4 in parallel group?

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looks good - just make sure to use multiple layers of nickel on the series connections - or even better reinforce with copper.

i wouldn’t say you have to attach each of the 8 wires to EACH of the 4 in parallel. you only need to attach to one in the four in parallel or just the tab and they’ll all have the same voltage

Hello, I am thinking of using a design like this my only question is where on each parallel group would you put the balance wire, and how exactly to make the bottom connection (the one that looks like a U on the very bottom) with nickel strip and a spot welder.

you can put the balance wires anywhere on the parallel pack and it’ll get the same voltage. maybe do a long strip of nickel for the bottom and spot weld the ends

Could I well the bottom + and the - by having the cells vertical then bending them flat after welding?

dont know how much bending the tabs can do. likely. but if you just spot weld the two tabs at the bottom…no bending necessary. you’ll need longer tabs in that instance

Im sorry but I need a visual or something to understand exactly what you are saying as I am having a hard time understanding it. I am very new to building packs which is why.

cant understand u either. If u do a drawing we will know

I am saying something like this. This is a mockup with AA and AAA batteries and only a pack of 2.

Weld them like this

Then bend them flat