Looking for a "get 'er done" no weld no solder battery assembly solution

I ordered a kweld spot welder with the intent of building a battery pack for my home-built KMX-framed velomobile the right way, but it will take months to arrive due to the disruption in the global shipping of goods.

I have everything I need to get my velomobile converted to electric except for a functioning battery pack. I'd like to get it rideable as an EV within the next month.

I have some A123 26650s in my possession that I intended to make a 24S4P pack with but a 24S LiFePO4 BMS I ordered back in July still hasn't arrived and has been sitting in a warehouse multiple states away for almost 2 months.

In order to speed up the prospect of me getting this thing rideable as an EV, I ordered 150 of the Panasonic NCR18650GA cells that were stripped from unused packs with minor blemishes(spot weld marks) on them, and a 20S 80A LiIon/LiPoly BMS that I ordered a week ago just arrived today. I'm intent on eventually building a 20S6P pack of the 18650s in the longer term, but in the short term, I may just do a smaller 20S3P or 20S2P pack just to hold me over until I get a spot welder.

I need a no-weld, no solder solution to assembling a 20S 18650 pack that allows for the following:

-No permanent damage to the cell
-Pack must be able to be disassembled at a later date for reusing the cells in a larger and/or more powerful pack
-Pack must reliably make at least 750W peak
-The risk of catastrophic failure and/or fire must be minimized during both use and during charging
-I need to be able to get the parts without waiting for months, preferably locally available at a hardware store for physical pickup

I looked at various topics on this subject throught the forums but it left me without an ideal solution.

The Vruzend no-solder kits tend to vibrate themselves apart, use unreliable components, and individual replacement pieces are near impossible to get. Then there's the issue of cells becoming extremely imbalanced over time. In spite of this, I'm tempted to order two of these kits just to get the trike converted, but I do not trust them and am confident that they are junk, and would prefer not wasting money if avoidable.

The NESE modules look like they would work, but if I ordered them, I am likely to be waiting 10 weeks. My spot welder will most likely be in my possession before then, defeating the purpose.

myzter's method looks appealing from this perspective(https://endless-sphere.com/forums/viewtopic.php?f=14&t=85714), and he seems to have had good results, and it is inexpensive, BUT I do not trust that this would be reliable for my application. The roads where I live are not in great condition and I regularly exceed 40 mph as it is without a motor, and worry that WITH a motor the vibrations will prove too much for the pack and maybe cause a catastrophic failure. Plus, I would not want a battery fire to randomly start between my legs while I'm mixing with automobile traffic at 30+ mph in an enclosed coffinmobile.

Magnets, copper busses, and foam might work, so long as I can cut through the foam at a later date and take everything apart again.(https://endless-sphere.com/forums/viewtopic.php?f=14&t=60517) But how easy/hard is it to do?

It would be easy to just order a pack, but I have yet to come across a 72V pack that is under $500, and for that price, I could build multiple 72V packs myself, IF I had the tools, and I do plan to build multiple battery packs once I get them, so this sort of expenditure seems to me an egregious waste of money. A 48V or 52V pack would only end up slowing me down due to motor cogging losses and the lack of deliverable power after it reaches max rpm, because as is, I can reach 37 mph on flat ground in a sprint just pedaling the damned thing without a motor at all, so a lower voltage pack is no solution either unless I can get it for extremely cheap(after all, I'm sure it would increase my rolling average speed and speed up hill, since cruising speed on the flat for me is more like 23-24 mph, but I really want to cruise at 35 or so and top out around 50+, which 750W may allow me to do when coupled with enough pedal force as long as I have 72V).


This is only meant to be a temporary measure. Once I get the spot welder, I plan to take apart whatever ghetto rigged contraption I end up building and put the pack together the right way so that I can draw 5 kW peak or more from it, which was the original intent for this vehicle.

But in the meantime, does anyone here know what would work well for my specific set of requirements?

Here's the main components I am going to convert the trike with:

-Leafbike 1500W 5T wind motor with cassette laced to a 26" rim
-Phaserunner controller
-Satiator charger
-Cycle Analyst v3 computer
-Sempu torque-sensing bottom bracket
-Banggood 20S 80A BMS
-Panasonic NCR18650GA batteries, probably initially as a 20S2P or 20S3P pack

The A123 pack is absolutely going to need a spot welder, as I plan to use that for racing and random acts of jackassery, which may entail a controller upgrade as well to the Nucular Electrics or ASI types on the market, but the Phaserunner will be plenty for now.

reinvent the wheel with your own jerry rig, and contribute it back to the community

A dozen bricks of RC lipo seems so simple after reading your post. I wonder why so many are into building batteries with hundreds of round cells.

MadRhino said:

A dozen bricks of RC lipo seems so simple after reading your post. I wonder why so many are into building batteries with hundreds of round cells.

Click to expand...

Automotive cells don't take dozens of bricks, and don't burn your house to the ground nearly so often.

Balmorhea said:

MadRhino said:

A dozen bricks of RC lipo seems so simple after reading your post. I wonder why so many are into building batteries with hundreds of round cells.

Click to expand...

Automotive cells don't take dozens of bricks, and don't burn your house to the ground nearly so often.

Click to expand...

Actually, since lico chemistry had taken over the round cell format, there are more fires caused by round cells than prismatic.

I'm probably going to try my own variant of myzter's method then, as it seems more reliable and less likely to unbalance my cells than a Vruzend kit. I'll wrap it in plastic wrap used for food storage, make a rectangular wooden box of tight fit that can clamp around the batteries at 4 corners using allthread and locking nuts to put the plastic wrapped pack in, put that in a fireproof bag, and use c-clips and cut up used innertubes to attach it to the trike frame. The cells might arrive today, and I have a choice of two 20S BMS in my possession to pick from to use in this first pack build(There's an 80A continuous one of questionable quality I got from banggood.com and a 35A cont/70A peak one I bought yesterday from ES user DanGT86). I probably will make a 20S3P pack and limit it to 750W.

I do not have a camera though to document this. I need to get one. I had one and it got stolen during a burglary years ago, and I haven't replaced it since, nor do I own a smart phone.

750W will make this little velomobile fly. I'm confident that this output combined with my pedaling could get me to 50+ mph on flat ground. A 20S3P pack should also, in theory, get me an 80-100 mile range at 30-35 mph with my pedaling accounting for 1/3 of the load. I've already been over 50 mph down hill without a motor at all.

I'll hopefully find out soon how this actually performs.

My 72V packs are two 36V packs in series. They are one battery with a switch to the bms that drops the voltage down to 36V or splits it in two. I use this when disconnecting and connecting the battery, cuts down on arching. Yes i'm sure most 36V batteries would not like to be in series but grins batteries would be good for this.

Grins batteries are currently beyond my budget. I'd be considering them right now if I hadn't already spent $350 on cells, $160 on BMSs, and another $250 for a spot welder that's on the way, but I already have enough LiFePO4 26650s to build a 700 Wh pack or thereabouts and enough LiIon 18650s on the way to make 2 kWh worth of packs.

My major gripe with Grins batteries, moreso than the high price, is the limited power draw. I'm looking to eventually come close to the limits of my selected motor and controller, and Grins batteries are not conducive to that, even though they are high quality, safe, and reliable systems. For the price I'd be paying for them, I could build a pack much better suited to my application. In the meantime, I'd be happy to run this thing with a ghetto-rigged pack at 1/10th of what it will eventually be run at once it is turned into a properly constructed pack.

It would be nice if I knew someone in my area with a spot welder, but I don't.