18650 golf cart battery build (14s40p)

Hi everybody ! Looking at some tips on bulding a golf cart battery out of 18650s this is what I would like to do.

1. Build a 48v 100ah battery to give a range of about 50km this is based on 90wh per km at 80% dod.

So my initial calculations and research suggest building 14 packs (3.7vx14) in series to give me 51.8v nominal.

Each pack must produce between 60 and 200A peak and average is about 80A on flat hill.

Looking at 2.6A cells capable of 4C (10A) such as the M26 or close I'm thinking of 40 cells in parallel per pack and an array of 4x10 cells with 2 busbars each with 5A fuse wire to each cell spot welded.

Now I have read that the lugs from each side (+ and -0) must be at opposite ends for best flow of energy
Or can keep them to one side of each parallel pack for securing ?.

I could build different pack configuration but I figured this would be the best for 560 cells also from a balancing point of view I will be using 2x ISDT 8T charger each on 7s of the pack side by side at 30A charge which will feed about 0.75A of charge per battery or about 0.35C on an M26.

Looking for ideas and possible mistakes I'm making in my calculations and also to open up a thread on building your own golf cart batteries.

This pack should replace my 4 Trojans lead acid batteries that weight 160kg for 7.2kwh or more like 3.6kwh since 50% discharge is recommended on lead acids to prolong life. And will only weigh about 25kg for 5.3kwh at 80% dod or 4.2kwh of usable energy !!!

If you haven't bought anything yet, maybe consider some kind of prismatic cells. There's a lot of easy ways to do the interconnects, including bolt together type so you can replace a cell, and the reduction in balance wires, and the reduced need for cell level fusing (you're taking a pretty deeply paralleled pack to where it's getting important) and the fact that you probably have a big blocky battery space to fill might make it worth thinking about.

https://www.techdirectclub.com/nissan-leaf-battery-g1-solar-back-up-lithium-ion-2-kwh-24-volt-66-amh-lot-of-4/

Something like this maybe?

Buying two lots= 8 modules each has a 2S2P battery inside, put 7 of them in series for a 14S2P 66Ah Battery.

@eee291 I think its a nice option but would you trust batteries that are already 7 years old (GEN 1 is 2011) ? I would if it was a new product I guess the price reflects the age ! But thank you for the idea.

I've had similar (NMC LG Chem) batteries from 2012 and they still show the same capacity after sitting 4 years in storage. I recently tested them and they showed
1-2mOhm internal resistance.

If I lived in the USA I would buy all of the batteries they offered. Most of them are Lithium manganese Cells which IMO have the best longevity and high power balance. They also don't catch fire like Lithium Cobalt when abused.

And the price is good, if you somehow managed to buy some directly from LG or Samsung you would be paying at least 2-3 times more.

Fair point ! I guess it's hard to tell if your getting value for money these days and even if.its a little dated it's still quality kit !