Building my very first battery pack.

Kesiux

1 µW
Joined
Aug 5, 2022
Messages
4
Hello Sphere,

So I've been following Facebook group for a while and finally got my cells delivered. I have 73Ah (Supposedly, haven't tested capacity yet) cells. 219A continuous discharge (0.8mohms IR) 325A peak.

I'm building a pack and I want it as safe as possible but at the same time as light and simple as it can be.
Here I'll attach all the pictures and its worth noting that I'm a true beginner. So any and all comments are very much appreciated but also some explanation as to why I should be changing things up would be nice.

So far I've built 11S but I'll be making 22S, just not sure of shape yet, either 1 big stack or 2 stacks next to one another. I'll know tomorrow. I don't have BMS just yet, so I know I'll have to tear some apart.
Anyway, please see my way of building and raise any concerns and provide with better solutions.

Most important aspect from this is education, so please be ever so kind and educate me on the things I'm blind to.
My main concern is loosening nuts and tab connections + isolation.

Dimensions:

16.5cm
34.2cm
10.2cm

11S 39.5V
Estimated weight 10.5kg

P.S, first half I used shrink wrap around 6 cells to hold them together, that was a bad idea, I'll be taping them together with kapton tape instead and shrink wrap at the end.
 

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Welcome Kesuix. Jp here.

Looks like a good start. You are keeping the cells isolated from one to the next, and insulating the buses well. Remember, this bus must carry full current without detriment.. and survive a short circuit event for a few milliseconds so a simple accident does not fry your entire pack. Electrical connections must be very strong and current capable. I will tell you the precautions I take, and the methods i have proven, shortly when i get time. The reasons I do what I do.. however.. It looks like you are off to a good start.
 
999zip999 said:
What's this for ? 73ah ??? That would be a big cell. 37ah ?

73Ah bro. This is for a currently 1.2kw hub motor scooter I have. Hope to get 150km range.
 
Kesiux said:
This is for a currently 1.2kw hub motor scooter I have. Hope to get 150km range.

Why? You like to ride your scooter past the point of discomfort? You can only charge once a week when you visit your mom? You want to go on century rides with bicyclists just to annoy them?

And where are you going to fit a cubic foot of cells and BMS on your scooter?
 
Chalo said:
Kesiux said:
This is for a currently 1.2kw hub motor scooter I have. Hope to get 150km range.

Why? You like to ride your scooter past the point of discomfort? You can only charge once a week when you visit your mom? You want to go on century rides with bicyclists just to annoy them?

And where are you going to fit a cubic foot of cells and BMS on your scooter?

Think I’ll fit it underneath the floor board or under the seat. I love to sit on dynamite.
 

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Maybe he just want to assure a long and healthy life by only ever using partial cycles, Chalo.

So 73Ah per cell. 3.7v nominal. 270 watt hours per cell expected capacity.

22s pack will be 81.4 volt nominal.

(81.4Vn) x (73Ah) = 5,942.2 watt hours total.

It will be interesting to see your final weight, in kilograms, and volume encompassed.
 
Have any more pictures of how you built it? And your source for the cells? I'd honestly like to do something similar and everyone here has different methods of bonding the tabs.
 
Not any more pics. Really these encompass all the process. On face I use Kapton tape, on the back I use (the tape that is green, it’s battery tape, don’t recall the name). And then tabs come different lengths so one folds over the other side with 2 screws. Although I’m thinking I might change it to be more sturdy. And then I use tape again, and Kapton tape to bond together. Afterwards I’ll be looking to make a case.

I work with suppliers, buying in bulk and resel. Coming from china.
 
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