Building an ebike... Just a few charging related questions.

So, I've built a 48v scooter that rips around great (Running on Lead Acid 12v 7.2ah batteries). I have a sound knowledge of how to put it all together, I've just never messed around with Li-ion batteries before (let alone configuring them to be super awesome).

Goal:
I'm looking to put together an actual town driving eBike. I happen to have found a source for LGABD21865 Li-ion cells. I've got about 70 so far. These are coming from new unopened and unused packages. So I could assume they're new. I was hoping to either make a 13s5p or I guess I can go higher if I wanted to(14s5p?). I've been looking into arduino spot welders https://malectrics.eu/product-category/arduino-spot-welder/, however I've come across these guys @ VRUZEND https://vruzend.com/product-category/battery-kits/. Are these useable? Also they offer BMS's https://vruzend.com/product-category/bms/. All that is great and assuming they work fine, I just have one problem... What's the best charger to use to charge these puppies once they're locked into configuration? Keep in mind I'm attempting to build this as low cost as possible. My main costs will be the largest hub motor I can buy, motor controller and Battery charger.

So to summarize:
1. Are the VRUZEND battery mechanism and BMS good enough to use?
2. Should I just invest in a Spot Welder for a similar price?
3. What's the best battery charger for $ ratio? (Just something off aliexpress?)
4. Any suggestions on Hub motors etc would be appreciated as well (otherwise I'll be doing the eBay route)

Thanks for any help I really appreciate it.

I have a lot of your same questions myself. Wondering about VRUZEND as well, and the best BMS if I use them.

So I've gone and purchased an Arduino welder https://malectrics.eu. And went to eBay to grab about 10 Meters in nickle. I've also ordered a 4 bay 1865 li-ion smart charger so I can equalize each cell in each section. I'm pending delivery on all of those items. I'm still wondering what's the best BMS and charging system to work into this (If I could get some input)

I've found this
for $179.99

I see this is a single gear bicycle, but it looks pretty sweet and would be awesome for my purposes with the welded rack on the back. Would putting a hub on here be a good idea? I have a pannier bag already so I can hide the batteries and any wiring inside. I have no experience with hub motors, the scooter I built has a mid drive setup and only a single gear.

I have enough to create a 13s5p battery (or a 14s5p if I wanted more)

Is there a decent place to get a BMS and charging solution other than eBay? Is there something I should be looking out for? I'm just trying not to waste money on junk. I'm hoping to create something half reliable.

I kinda did something similar to cruiser like this. It was a nice 7-speed, with front and rear rim brakes. Wanted the biggest motor so I wouldn't be lacking. Also wanted a rear hub motor,... want of conventional drive maybe, and wasn't fond of the thought of regen and powering the front.

And THAT'S where it all got outa hand.

I gotta 1500w rear-hub,... a bit of "overkill" for jus cruisin' about. But I figured the frame could handle it. Things started getting REALLY outa hand then!

Battery??? Considered lead/acid,... briefly. Thought about buildin' a brick too,... got good skills and knowledge. Some how, talked myself into a good quality battery,.. and that would mean a well built LiPo. MORE overkill as I chose a 52V over a 48V,... don't ask! But now I got 2000w of a screamin' monster, for jus a bit cruising. UGH!

The bike You have shown has coaster brakes,... that's gone with a rear hub conversion. And adapting disk brakes without welding tabs on the frame, is a damn pain!!! I quickly found my stock rim brakes to be grossly inadequate when cruisin' at 20mph or even more. Mine easily hit 40 and shocked me! Converting the front to disk??? It was absolutely necessary, so I ended up with new forks with tabs for disks AND a front disk wheel assy!!! UGH! Happy I got good disk brakes,... even if most of my cruising is below 20mph, rim brakes jus wouldn't cut it. BTW,... your choice has NO front brake, nor any way to accommodate something decent.

A build can easily get outa hand!!! Some is necessary to accommodate the basic conversion, some is necessary for reasonable safety. And some is jus foolish desire!!! Don't get me wrong,... I LOVE my cruiser. It CAN be extreme,... but I keep it reasonable and mild.

Now if your jus considerin' something easy, as I should have,.... you'll find a 48V 1000w front hub is more than quite adequate. Reasonably controller adjustments of output and light regen braking would be fine with the expected 20mph max speed, a bit of reasonable controlled slowing regen on the "brakeless" front end, and sufficient torque without to much trouble on anything but extremely loose surfaces, you know,... a simple town and country cruiser. That coaster brake will be fine,.. the added battery weight above, an advantage. You'll lock it up when necessary! No problem. Heck,.. can't stop much quicker than skiddin' to a stop.

And a simple town and country conversion should be easy, dependable, reasonable,... and NO PROBLEM! IMO!

I do have the full ability to TIG weld any adjustments necessary. I kinda want this thing to go faster than my scooter which does about 30kmph and it's hilarious to ride. honestly I didn't even put a thought about the brakes. lmafo jesus. I've got these batteries, so I might as well use them and build myself a big Battery with a BMS. I laughed when I saw no front brakes, and that old style coast brakes and laughed to myself, but the price is right. (I currently have a mountain bike with a derailleur and more gears than I've ever used/seen as a kid so idk what I'm going to use.)

I was going to grab a 1500W rear hub as well. and if you're pulling 40mph @ 52v it sounds exactly like what I'm trying to build. I'm curious to see how far I can get on a charge once it's all ready to go.

I have a small 11.5ah 52V pack that will push 45amps. With my 40amp controller on max settings,... it's an ASTONISHING cruiser!!! Motorists sometimes seem frustrated with a bicycle nearby,.... till I leave them at the light and they find they can't catch up on the 35-40mph village streets. Some would think of me as "an outlaw",... but even the outlaws are shocked as I cruise thru town beside them, all, nodding in approval.

Those maxed settings see 38-40 easy enough, the front gets real light from a dead stop. The small shift in weight from a laid-back seat-post often saw the front end "flying" in abrupt starts. Only about 10-12miles of wild riding. By the time any temps get to affecting levels,... I've run out of battery. But cut my controller back a bit, and limit my speed to 20mph and I'll double my mileage to 20 or so with no issues. With 20A output settings and speed limit of 15,.... I can enjoy a 35+mi cruise. Hills have an effect, of course,... but those findings are based a pretty heavy 29" cruiser over gentile paved terrain.

Bear in mind that those max settings can place me in an "unlawful motor vehicle" with some sever penalties in violation of many laws!!! So mostly I keep it mild,... then I'm jus "an old man on a fancy bicycle".

I too like having a tig set-up,... will make my next build much easier.