Questions about building 48v battery pack for the first time

Hi all,
I'm building my first battery pack and have some questions,
A month ago i got 10pcs of 2200mAh 36v packs with 10 cells each that seems to be a brand new but a little bit old (about a year or 2),
After testing each cell out of those 100 individually, the average capacity of them is 2050mAh (between 1500 to 2300).
Now i'm thinking if i should go for 13S7P or 13S6P,
if i'll go for 7P the lowest cell capacity will be 1500mAh,
if i'll go for 6P the lowest cell capacity will be 1800mAh,
considering that i want to get as much Amps as possible (and of course capacity as well) i'm thinking to go for 7P but i'm afraid that using those extra 13 weaker cell will affect the whole battery performance.
is it true? what should i go for?

another question - i also checked the resistance of each cell before discharge and after discharged, the results was between 66ohms to 160 while most of them are around 110, after full discharge the resistance was a little bit higher.
which one is the correct result ? and what should i think of when i'm splitting the cells to parallel groups resistance wise ?

Hope it was clear enough,
Thanks!

After playing with probably the same cells I decided to take 98 cells of the lg variety and make a 14s7p pack. I use 6 amps on my journey with no voltage sag, compared to my 20a 48v luna pack that sag like crazy. My end result is pulling the nrcb cells out of the 48v and making a 52v pack. What I’m getting at is using a slight elevation in volts you can use a few less amps making the battery happier and your ride a little faster. If your using the cells like mine then build in as much amperage as you can if you have the room. It’s a hard call weither to go 48 or 52v, I’m converted but I had the luck of buying a statiator so I didn’t need a new charger, the financial implications may make this a non starter but if you can build in more amps you problably won’t see much difference this year, but getting away with charging to 80% and having the battery run cooler will pay dividends in the extra cycles you will see at the end of the pack. Go with the extra parallel group if your whole system does not exceed the weakest group.

Thanks for your reply.
so do you think using also the weaker cells will perform better than building a pack with one less cell in P ?

and what about the resistance ?
what should i think of when i'm splitting for groups of 6/7 cells? (in addition to balanced total capacity of each group)

Thanks again

From what I gathered you balance like for like, so your worst cells go together and that is your lowest performing group, it still increases your overall amperage but the whole pack will only perform as well as the weakest group meaning when that group discharges it doesn’t matter how much is left in the remaining cells because your weak group has reached their limit, but that limit will take longer to reach the more parallel groups you have, if you have a known bad group of cells then they should be eliminated but if they are recoverable I would try that first. I took the weakest group and put them in a paralllel configuration and did the same with the strongest. Charged the weakest ones to 4.1 and discharged using a few light bulbs. Then compared that with the supposed strongest group, the difference with groups of 7 was 0.6Ah and I built 50% more capacity than needed as I use it on my heavy scooter as well so losing 0.6 Ah overall was of little consequence being the cells are so cheap. I used the cheap watt meter to measure the discharge rates and the voltage is inaccurate for measurement but I figured I want repeatable results rather than the set value but be wary as mine read .4v over making me think I over charged my cells. If your weak group is unacceptable ( I’ve yet to find some that haven’t settled down after days of balancing and slow chargeing and discharging to even them all out) you need to think if you really want them in your pack because they will be the first to reach full voltage on charge cycle and have a high risk of overcharging, that’s not acceptable to me. Also on ripping apart my luna pack I saw what a difference a Ali-express bms vs a decent one looked like, the cheap ones next to them look pityfull but I didn’t know any better and my one is performing just fine, but for extra protection especially if your taking a risk with the cells it’s probably wise to buy a bms with higher balance rates to get the charge out of any cells over charging quicker.

Didnt read anything but the title.

First is study
Next is TRIPLE CHECK EVERYTHING - You know the old motto, measure 10 times cut once
Finally - Be VERY CAREFUL

I am checking my battery pack right now, I have the bare tabs showing, and making sure as shit there are no conductive materials that can accidentally drop on the tabs.

markz said:

Didnt read anything but the title.

First is study
Next is TRIPLE CHECK EVERYTHING - You know the old motto, measure 10 times cut once
Finally - Be VERY CAREFUL

I am checking my battery pack right now, I have the bare tabs showing, and making sure as shit there are no conductive materials that can accidentally drop on the tabs.

Click to expand...

that's exactly what i'm doing,
if you're checking your battery pack right now, maybe can you share some testing methods?
i know it is one step forward but it will be great to read thanks