What to expect?

B

brafi

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Jul 12, 2017
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Hi

I just got a box of used laptop-batteries, and have harvested all the 18650s. Now I have 244 batteries, and are waiting for my TP4056 for chargingandLiitokala Lii - 500 fordischarging.

How many batteries should I expect to be dead?

My plan is to useall above1800mAh for 1s100p bricks, but is this to much?
 
I expect 45% to work ok on random packs.

Dont build your bricks untill you have all batteries you need for the full string. I say this because then you can apply random on it and will get all cells spread equally among the packs. Thats how i do it.
 
Thanks. I'll start building packs, when I have all the cells.
Is it correct that I should mix the cells, to have almost the same amount of 1800, 2000 and 2600 mAhs in the same pack?
How low on capasity would you recommend pr. cell?
 
Firstly i sort all my cells available. Then i pick out the cells that suits best to build the string im aiming for. If I have 1000 cells and i need 800 i pick out the best 800 cells to build with. then i mix those up and then just build the packs.
This way it "should" stay somewhat even. I dont like ranging them with any utilitity or by single mAh.
Why? Because first of all the testers are very very inaccurate if you ask me. It differs alot. Secondly we are handling with 2nd hand cells. If we would take all scenarios of a cell including meassuring with expensive equipment it may work to arrange specificly but i dont think it works for this purpose.

I run BMS so i can do a full cycle every now and then and this will tell me if I have any pack that is way off. And if so i can look into that pack and swap out cells.
I think the time i save on this by just meassuring once and then just mix em will in long run work out if i need to swap out a pack. I have seen several packs done 100% by per 1mAh but still it didnt last much longer.

Its still worth understanding that i have only done the diy cells for about 2 years and the cell for solar for roughly 1 year. So im not an expert nor do we have enough numbers to state whats what.

I only go to 2Ah currently. Because that have suited the cells i have. Ie 2-2.8Ah cells.

I have built packs down to 1800 but they are their own strings.
 
daromer said:
Firstly i sort all my cells available. Then i pick out the cells that suits best to build the string im aiming for. If I have 1000 cells and i need 800 i pick out the best 800 cells to build with. then i mix those up and then just build the packs.
This way it "should" stay somewhat even. I dont like ranging them with any utilitity or by single mAh.
Why? Because first of all the testers are very very inaccurate if you ask me. It differs alot. Secondly we are handling with 2nd hand cells. If we would take all scenarios of a cell including meassuring with expensive equipment it may work to arrange specificly but i dont think it works for this purpose.

I run BMS so i can do a full cycle every now and then and this will tell me if I have any pack that is way off. And if so i can look into that pack and swap out cells.
I think the time i save on this by just meassuring once and then just mix em will in long run work out if i need to swap out a pack. I have seen several packs done 100% by per 1mAh but still it didnt last much longer.

Its still worth understanding that i have only done the diy cells for about 2 years and the cell for solar for roughly 1 year. So im not an expert nor do we have enough numbers to state whats what.

I only go to 2Ah currently. Because that have suited the cells i have. Ie 2-2.8Ah cells.

I have built packs down to 1800 but they are their own strings.
Click to expand...
Thanks. I'll collect all the batteries first and then start building it as you wrote.

Thanks, and keep up the great work with vlogs and so on! [emoji3]
 
Daniel, do you mix them really all together, or do you random'ly try to distribute from similar ranges of mAh? like random distribute all cells from 2000-2100 to all 14 packs, then similarly 2100-2200, and so on?
 
Frnando. I mixe so i get same amount for each 100mAh span to each pack.

So if I dont have enough of the 2100mAh range (2100-2200) I first spread those out evenly and then go to next range (2000) and spread those out.
 
I didn't mix mine but I put them in order of biggest to smallest going back and forth between the 4 packs.
If your loging usage and volts, you should be able to tell if you need more or less cells in a pack.

I have the SBMS100 so I am just going to cut fuses if I have too much amps in 1 pack to balance it out.
 
video from back in the old days :D

 
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