Is THIS the Battery of the Future (Weldless)
video description
Date: 2026-03-07
Related videos
Comments and reviews: 20
GENcELL2014
Finger or flexure contacts with an elastomer backing for compression element is a far superior approach vs having pcb fiberglass core or a conductor material be flexure and compression element.
Lets the flexure be weaker and more easily moved or flexed with a greater compression range, while the elastomer can be made from different elastomeric compounds to fine tune contact force. They already need a paper insulator between pcb and metal cover so just make it out of an elastomer or adhere or impregnate the paper insulator with an elastomer in the region directly above of each pcb flexure aka finger contact.
The elastomer compression element approach can provide far higher contact forces with a greater compression range and works better in high vibration or g force applications, like a ebike or emotorcycle. I don't doubt they can have decent contact force with a fiberglass flexure but it'll inherently have less compression range and potentially less contact force a mobile solderless battery application truly needs.
reply
Finger or flexure contacts with an elastomer backing for compression element is a far superior approach vs having pcb fiberglass core or a conductor material be flexure and compression element.
Lets the flexure be weaker and more easily moved or flexed with a greater compression range, while the elastomer can be made from different elastomeric compounds to fine tune contact force. They already need a paper insulator between pcb and metal cover so just make it out of an elastomer or adhere or impregnate the paper insulator with an elastomer in the region directly above of each pcb flexure aka finger contact.
The elastomer compression element approach can provide far higher contact forces with a greater compression range and works better in high vibration or g force applications, like a ebike or emotorcycle. I don't doubt they can have decent contact force with a fiberglass flexure but it'll inherently have less compression range and potentially less contact force a mobile solderless battery application truly needs.
reply
MegaSteamfreak
I think it is dangerous to rely for a long time on a 3D printed battery pack case like the one shown.
Plastic always de forms over time, thus the pressure on the contacts decreases constantly! Your contract resistance will go up and with higher temperatures the plastic gets even weaker.
The spring loaded one is a better way, but I still would use it for rather low currents.
The bought pack works, because the pressure is applied by materials that don't deform by time and heat.
And claiming 1W power loss is not much/negligible is simply bad advice. A 2. 5Ah, 7. 2V Pack has 18Wh of energy. Wasting 1W to heat wastes 5. 6% of the total energy. And this does not even factor in, that with higher currents you can't use the full capacity. So at 10A or even 20A you might loose 10% of your energy to heat and have the risk of your pack melting!
reply
I think it is dangerous to rely for a long time on a 3D printed battery pack case like the one shown.
Plastic always de forms over time, thus the pressure on the contacts decreases constantly! Your contract resistance will go up and with higher temperatures the plastic gets even weaker.
The spring loaded one is a better way, but I still would use it for rather low currents.
The bought pack works, because the pressure is applied by materials that don't deform by time and heat.
And claiming 1W power loss is not much/negligible is simply bad advice. A 2. 5Ah, 7. 2V Pack has 18Wh of energy. Wasting 1W to heat wastes 5. 6% of the total energy. And this does not even factor in, that with higher currents you can't use the full capacity. So at 10A or even 20A you might loose 10% of your energy to heat and have the risk of your pack melting!
reply
gendragongfly
Bolted connections need to be loaded in tension (not in compression) and require a length / diameter ratio of 1. 5 to get a good stretch in the bolt to resist loosening over time as a result of vibration and temperature changes. (Bolts need to be long) Springs are a better solution, but the spring type used in the AliExpress product is wrong. You want high load in a compact form factor and coil springs are not that. Leaf springs, or more specifically disk springs would likely be ideal. Additionally, using nickel strips with spring loaded contacts is sub-optimal. Nickel plated copper is a much better option. Higher conductivity, better ductility (better compliance under pressure. There is a reason the wago connectors also use leaf springs
reply
Bolted connections need to be loaded in tension (not in compression) and require a length / diameter ratio of 1. 5 to get a good stretch in the bolt to resist loosening over time as a result of vibration and temperature changes. (Bolts need to be long) Springs are a better solution, but the spring type used in the AliExpress product is wrong. You want high load in a compact form factor and coil springs are not that. Leaf springs, or more specifically disk springs would likely be ideal. Additionally, using nickel strips with spring loaded contacts is sub-optimal. Nickel plated copper is a much better option. Higher conductivity, better ductility (better compliance under pressure. There is a reason the wago connectors also use leaf springs
reply
kapitan. unitaza
Always liked your videos but I'm going to call BS on this one. 1. Sure it is difficult (but not impossible though not recommended) to tear off a spot weld with your bare hands! Needle nose pliers, however, do a great job of removing spot-welded nickel strips. With a little practice and some luck you can even do so carefully enough to be able to re-use (also not recommended) the strip and / or cell. 2. As you have stated: the only reason to remove a cell from a pack is to replace it. Then why would you care about saving either the bad cell or the nickel strip Just snip it with regular scissors and weld a section of new nickel strip on top! Additional resistance of a spot weld itself, again as you have measured it, is negligible.
reply
Always liked your videos but I'm going to call BS on this one. 1. Sure it is difficult (but not impossible though not recommended) to tear off a spot weld with your bare hands! Needle nose pliers, however, do a great job of removing spot-welded nickel strips. With a little practice and some luck you can even do so carefully enough to be able to re-use (also not recommended) the strip and / or cell. 2. As you have stated: the only reason to remove a cell from a pack is to replace it. Then why would you care about saving either the bad cell or the nickel strip Just snip it with regular scissors and weld a section of new nickel strip on top! Additional resistance of a spot weld itself, again as you have measured it, is negligible.
reply
PhilippG88
When using the 3d printed or the Aliexpress holder, be careful about the clamping! Not only can your screw loosen over time, but the screws (or the studs in the Aliexpress holders) brace against the housing. The housing will weaken, if the battery pack gets warm due to being used or due to outside heat. This can cause the housing to deform, further increasing the resistance. Also, with several thermal cycles, the material can get brittle and deform or break.
How do i know that About 13 years back, i got such a clamp arrangement approved for the use in Formula Student Electric Germany and we had a very lengthy discussion about clamping cells while including plastics in the stack up.
reply
When using the 3d printed or the Aliexpress holder, be careful about the clamping! Not only can your screw loosen over time, but the screws (or the studs in the Aliexpress holders) brace against the housing. The housing will weaken, if the battery pack gets warm due to being used or due to outside heat. This can cause the housing to deform, further increasing the resistance. Also, with several thermal cycles, the material can get brittle and deform or break.
How do i know that About 13 years back, i got such a clamp arrangement approved for the use in Formula Student Electric Germany and we had a very lengthy discussion about clamping cells while including plastics in the stack up.
reply
junkerzn7312
That 3D printed pressure retention, which is what you are relying on, is NOT safe. It isn't even close. Any heat will, over time, cause the case to distort and will loosen the cell contacts. Guaranteed. Welding / spot-welding is far better and far safer. when it is done properly. which it wasn't with that dinky little spot welder. 4 spot welds per cell.
Doubly or triply-so if using NMC or NCA cells and not LFP. Don't mess around with NMC or NCA. To be honest, I'd stop using NMC and NCA entirely, in fact. LFP or nothing. But I know that's a hard sell to people who like the energy density.
-Matt
reply
That 3D printed pressure retention, which is what you are relying on, is NOT safe. It isn't even close. Any heat will, over time, cause the case to distort and will loosen the cell contacts. Guaranteed. Welding / spot-welding is far better and far safer. when it is done properly. which it wasn't with that dinky little spot welder. 4 spot welds per cell.
Doubly or triply-so if using NMC or NCA cells and not LFP. Don't mess around with NMC or NCA. To be honest, I'd stop using NMC and NCA entirely, in fact. LFP or nothing. But I know that's a hard sell to people who like the energy density.
-Matt
reply
kraftzion
I really would like to see further exploration on this topic. Maybe copper strips with idk dielectric grease or something to prevent oxidation at the interface. I am currently sitting on some molicel 21700 batteries p42s 45a. Probably going to soldier. Some knowledge I can bring to the table that maybe you or somebody else can benefit from. The green makita charger will charge a battery when the green and black one declares it dead. Probably not useful in this scenario lol but can be. Aka depth of discharge limit lower on green charger I believe is the difference.
reply
I really would like to see further exploration on this topic. Maybe copper strips with idk dielectric grease or something to prevent oxidation at the interface. I am currently sitting on some molicel 21700 batteries p42s 45a. Probably going to soldier. Some knowledge I can bring to the table that maybe you or somebody else can benefit from. The green makita charger will charge a battery when the green and black one declares it dead. Probably not useful in this scenario lol but can be. Aka depth of discharge limit lower on green charger I believe is the difference.
reply
horrovac
Sooo. Battery packs without spot welds suck
Dealing with low tension, losing tension, deforming due to combined tension, corrosion, galling, arcing etc. is WAY more hassle than just welding it all together. I have some thick nickel strips and also nickel-plated copper strips (also thick, and you can put as many spotwelds on them as you wish.
I would have used something like wide desoldering braid with the flux washed off. That should create a whole bunch of quite good contact points and is probably your best bet for getting the contact resistance low.
reply
Sooo. Battery packs without spot welds suck
Dealing with low tension, losing tension, deforming due to combined tension, corrosion, galling, arcing etc. is WAY more hassle than just welding it all together. I have some thick nickel strips and also nickel-plated copper strips (also thick, and you can put as many spotwelds on them as you wish.
I would have used something like wide desoldering braid with the flux washed off. That should create a whole bunch of quite good contact points and is probably your best bet for getting the contact resistance low.
reply
henninghoefer
TBH, I think carbon fiber nylon might be the worst possible filament to build a battery enclosure:
Carbon fibers are electrically conductive (as everyone finds out when they try to dry their CF filament in the microwave)
Nylon creeps under constant tension (as everyone finds out when they print their Voron parts from Nylon instead of ABS)
So with a nylon case you'll soon have the same issue as your badly welded pack.
And if you're _extremely_ unlucky, your case might be a bit conductive, too (depends on random fiber orientation though.
reply
TBH, I think carbon fiber nylon might be the worst possible filament to build a battery enclosure:
Carbon fibers are electrically conductive (as everyone finds out when they try to dry their CF filament in the microwave)
Nylon creeps under constant tension (as everyone finds out when they print their Voron parts from Nylon instead of ABS)
So with a nylon case you'll soon have the same issue as your badly welded pack.
And if you're _extremely_ unlucky, your case might be a bit conductive, too (depends on random fiber orientation though.
reply
greatscott
the guys from second ride are genius. but especialy in my non-suspensioned e-scooter, the enviroment for the pack is hard. can't imagine that this maki batteries principe eats vibrations like a spot weldet pack. so, genius but not for every situation i think. the next thing is, i build a bunch of battery packs for e-scooters in the past, also my own too, and i never had to replace a bad cell. especialy the 21700 cells are quite robust in high peak loads. the best usp of the maki battery is the cooling tapped to the cell bottom.
reply
the guys from second ride are genius. but especialy in my non-suspensioned e-scooter, the enviroment for the pack is hard. can't imagine that this maki batteries principe eats vibrations like a spot weldet pack. so, genius but not for every situation i think. the next thing is, i build a bunch of battery packs for e-scooters in the past, also my own too, and i never had to replace a bad cell. especialy the 21700 cells are quite robust in high peak loads. the best usp of the maki battery is the cooling tapped to the cell bottom.
reply
skopyhoTechChannel
I think those spotweld free battery connection will have much lower reliability than welded packs. spot welded packs with 18650 cells are used 20 years. and even at maker level, you can buy decent spotwelder for 200Eur which makes reliable spotwelds. (or build k Weld for 100eur. those single cell spot welders from aliexpress could make good spot weld only in perfect conditions. Weld less packs make sense only for very low power application, like flashlights or phone chargers, but i will never used them for 20A load
reply
I think those spotweld free battery connection will have much lower reliability than welded packs. spot welded packs with 18650 cells are used 20 years. and even at maker level, you can buy decent spotwelder for 200Eur which makes reliable spotwelds. (or build k Weld for 100eur. those single cell spot welders from aliexpress could make good spot weld only in perfect conditions. Weld less packs make sense only for very low power application, like flashlights or phone chargers, but i will never used them for 20A load
reply
geekmystique
good for small projects, but it simply makes -no- sense for bigger packs. The risks of pressing are too high- what if the terminals are not clean, what if the springs lose springiness - also cost is just too high, nickel strips and equipment needed are cheap and fool proof. If you build a good pack it is not very likely a single cell will go much sooner than the others. Also with the low cost of lithium cells it is not worth the effort financially, encasing, BMS, assembly is already over 25% of pack cost at the moment.
reply
good for small projects, but it simply makes -no- sense for bigger packs. The risks of pressing are too high- what if the terminals are not clean, what if the springs lose springiness - also cost is just too high, nickel strips and equipment needed are cheap and fool proof. If you build a good pack it is not very likely a single cell will go much sooner than the others. Also with the low cost of lithium cells it is not worth the effort financially, encasing, BMS, assembly is already over 25% of pack cost at the moment.
reply
douglasvaughan9483
What was the resistance of cutting a cell out and replacing it with a new cell with new spotwelded tabs/flanges. Think of three capital T standing next to eachother. The vertical portion represents the cell and the horizontal is the conductive material between the cells. You cut the arms of the bad cell as tight as possible, so it looks like an I. Then you replace that cell with a new T that gets spot welded to the adjacent T. Basically what is the impact of multiple layers of spot-welded material.
reply
What was the resistance of cutting a cell out and replacing it with a new cell with new spotwelded tabs/flanges. Think of three capital T standing next to eachother. The vertical portion represents the cell and the horizontal is the conductive material between the cells. You cut the arms of the bad cell as tight as possible, so it looks like an I. Then you replace that cell with a new T that gets spot welded to the adjacent T. Basically what is the impact of multiple layers of spot-welded material.
reply
bythelee
It is far too easy to put a cell into the spring loaded (or any removeable / replaceable battery) the wrong way around.
I've done this myself, particularly when it is not obvious which way around the cells should go.
The danger is not so much the spot weld coming adrift, as the user messing up with a facepalm error.
As such, I feel these batteries should NOT be produced in a way that invites user maintenance or user replacement. Otherwise, make sure your fire insurance is good.
reply
It is far too easy to put a cell into the spring loaded (or any removeable / replaceable battery) the wrong way around.
I've done this myself, particularly when it is not obvious which way around the cells should go.
The danger is not so much the spot weld coming adrift, as the user messing up with a facepalm error.
As such, I feel these batteries should NOT be produced in a way that invites user maintenance or user replacement. Otherwise, make sure your fire insurance is good.
reply
sjbechet1111
You might want to check out Prof Paul Christensen or Patrick Durham (StacheD) on just how dangerous Lion chemistry is. EV's with this chemistry have destroyed 3 car container ships (2 of them sank) the Felicity Ace 2022 - Freemantle Highway 2023 - Morning Midas 2025.
A scooter size battery pack is more than capable of creating a vapour cloud and subsequent deflagration (explosion) that can destroy a house - This is the reason EV's are being banned from contained parking.
reply
You might want to check out Prof Paul Christensen or Patrick Durham (StacheD) on just how dangerous Lion chemistry is. EV's with this chemistry have destroyed 3 car container ships (2 of them sank) the Felicity Ace 2022 - Freemantle Highway 2023 - Morning Midas 2025.
A scooter size battery pack is more than capable of creating a vapour cloud and subsequent deflagration (explosion) that can destroy a house - This is the reason EV's are being banned from contained parking.
reply
LackofFaithify
Been using 4 26650 LFP in series held in a 3D printed case with heat fit spring tabs to power LEDs for a while (4 years or so. Works fine, have 4 in reserve so when I need to once every 4-5months, I just swap them out and recharge in a SKYRC 3000. Batteries are all still healthy. Of course they are pulling nothing like 20A, I think it is closer to 2. 5-3A (they are rated for 15A or 20A continuous, don't remember which) and they are totally stationary.
reply
Been using 4 26650 LFP in series held in a 3D printed case with heat fit spring tabs to power LEDs for a while (4 years or so. Works fine, have 4 in reserve so when I need to once every 4-5months, I just swap them out and recharge in a SKYRC 3000. Batteries are all still healthy. Of course they are pulling nothing like 20A, I think it is closer to 2. 5-3A (they are rated for 15A or 20A continuous, don't remember which) and they are totally stationary.
reply
anon_y_mousse
I've always liked battery compartments with springs. They provide continuous pressure yet make it easy to swap cells. You can print a slot in that first case instead of a hole and slide the end of a spring in there with it already pre-welded to connect them all together. If you look at the battery compartment for portable devices that use AA batteries, you'll see the same design. You should try those out and see what kind of resistance you get.
reply
I've always liked battery compartments with springs. They provide continuous pressure yet make it easy to swap cells. You can print a slot in that first case instead of a hole and slide the end of a spring in there with it already pre-welded to connect them all together. If you look at the battery compartment for portable devices that use AA batteries, you'll see the same design. You should try those out and see what kind of resistance you get.
reply
peppi0304
I have a wifi thermometer that is not really made for outdoor use. Despite that i put it outdoors. And after a year of use. The spring got really stiff and the contact stopped. I had to stretch out the spring again a bit for it to work again. Im guessing it depends on the metal you use for the spring if it can handle daily temperature ranges. Then again i know from my grandfather that you always loosen every spring as long as you dont need it
reply
I have a wifi thermometer that is not really made for outdoor use. Despite that i put it outdoors. And after a year of use. The spring got really stiff and the contact stopped. I had to stretch out the spring again a bit for it to work again. Im guessing it depends on the metal you use for the spring if it can handle daily temperature ranges. Then again i know from my grandfather that you always loosen every spring as long as you dont need it
reply
CM-tq4zv
18650s and 21700 cells have been used to dangerous failure in weldless setups. The micro fracturing of the cell can at the point they are compressed by the springs or torqued pressure connectors after vibration work hardens and vents the cell. These setups have no listing or certification because they fail and can fail catastrophically. Bad idea and dangerous that comes back every few years and flames out again - pun intended lol
reply
18650s and 21700 cells have been used to dangerous failure in weldless setups. The micro fracturing of the cell can at the point they are compressed by the springs or torqued pressure connectors after vibration work hardens and vents the cell. These setups have no listing or certification because they fail and can fail catastrophically. Bad idea and dangerous that comes back every few years and flames out again - pun intended lol
reply
LerrySanders
Im so sick of bambu lab sponsored segments. With the amount of money they are shilling on their products it makes me NOT want to buy their stuff. Im sorry. I just cant keep watching this video. I love your videos and the tech you do but Im so sick of them I just have to stop watching. Its gotten to the point where I wonder if people are making videos are put ads in them, or making ads and wrapping a video around them.
reply
Im so sick of bambu lab sponsored segments. With the amount of money they are shilling on their products it makes me NOT want to buy their stuff. Im sorry. I just cant keep watching this video. I love your videos and the tech you do but Im so sick of them I just have to stop watching. Its gotten to the point where I wonder if people are making videos are put ads in them, or making ads and wrapping a video around them.
reply
Add a review, comment
Other channel videos
11:23
