Community spotwelder? I’m kinda confused lol. Is this like, a loaned out spotwelder? I think it’d make more sense for me to just buy a budget one outright 
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Yep, that’s right there is a shared community one, it’s been around for years and to a lot of people. We just pay postage from the last person to us. I believe @Halbj613 donated it.
Just in case you wanted to save money bc it’s a once-off thing and you wouldn’t use it for building esk8 packs.
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The 18650 ‘tabless’ Ampace JP30 and Eve 30pl should add some more spice, to the hot rod mod, but who knows when they will be available.
Torque test channel on Youtube recently had a Molicel p28a modded pack perform very well. A while back they tried to modify a battery with p42a, and were underwhelmed, as the series connects were too thin. When they got a fatter welder and stacked thicker strips it performed quite well.
I’ve sucessfully welded 0.1mm copper with 0.1mm nickel plated steel sandwich, with a 22$ ’ purple’ spot welder, using a 36$ 3s 5.2 ah ‘Zee’ lipo, which are kind of bottom of the barrel Lipo. I modified it slightly for better performance, and first feed it a second 12v battery, via a xt90s, to keep the gate switching voltage high and inrush current down on powerup.
Red Weld probe Uses a + off lipo weld battery xt90s itself, welder just triggers -, so just hook both batteries - to Cirbuit board -
If gate switching voltage falls too low during a weld, magic smoke escapes as mosfets fry.
I’ve built a 10s1p and 10s2p with it, so far, and 2 3s1p packs as well, and it has endured a couple hundred test welds too.
I think a better Lipo would allow it to weld 0.15mm copper and 0.1mm NPS sandwich, which should be the equivalent resistance of 0.6mm pure nickel.
My heart is breaking right now.
To be fair tho, I’ve never used a cheap one, not sure on what the options be
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I think there’s a P28B rated to 40A but it doesn’t actually outperform the P30B in current but it does at low power it’s a little weird.
I went looking for 18650s to recommend instead of the P30B for ac53n but it’s tough the P30B is solid. Maybe the VTC6 but for some reason the tests put it at 15A maybe it’s an older version or something.
I have P30Bs coming for my grandad too he wanted 18650s to last a while so I thought I would do my best.
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I was unaware of the p28b. It does seem like the p30b is the best available 18650 power cell, at the moment.
Deal wise, in USA, this might be the current winner chicken dinner.
vtc5d for 2.50$
I got a hankering to build a cordless vaccuum battery, but the one it came with lasts longer than I need, for now.
The VTC6 is rated at 15A continuous by the manufacturer. It has a 30A temp-limited (to 80°C) rating too though.
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Agreed.
The P28B was a test cell with a short production run to validate the chemistry for use in the P30B. The P28B was not a full production cell and is not made anymore,
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That’s only about a 2.4% difference in delivered energy at 5A though, easily accounted for by a grade change or cell to cell differences. It would be unnoticeable in actual use.
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I bought one of the cheap red spot welders you can find on eBay, amazon, aliexpress, etc. Mine was an “upgraded” one that no longer has the issue where the controller gets low voltage regularly during the welds and causes the whole thing to blow up, but what version you get is mostly a roll of the dice, and you need to be able to identify the version and check if there are any necessary fixes. There is some good info about the versions and fixes on youtube. I’ve only welded a couple of smallish packs, but it has survived and produces passable welds on 0.2 mm nickel. You do have to go slowly or take breaks, though. I’d say if you do ~25 individual welds, so about four cells at three welds per end of a cell, it starts getting hot enough that I thought I should let it rest some.
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There has been at least 4 versions of the CheApo Red spot welder going back 5 years now.
The one I got was slightly different than any I saw modified online. I used it a bunch without any modifications.
The early recommended modifications were designed to keep low weld battery voltage from frying the mosfets. There is also the inrush current blowing up a diode after a few power ups. The mods were largely add a capacitor here, add a resistor there or desolder it and change its value.
I performed no capacitor or resistor modifications to my Red, or purple cheapo spot welders
I swapped my Zee lipo from xt60 to Xt90s.
I used a second 12v battery to power circuit board, also via an xt90s antispark connector. These seem to eliminate the major FET frying issues.
I found my Purple spot welder to have about 40% more power than my red one using the same welding pens and weld battery. Im thinking about acquiring a backup purple welder, if/when I next build a battery, just in case. There is a newer double pulse purple welder out now too.
More info on the cheapo spot welders here:
Neither of my cheapo welders had issue with 0.15 pure nickel, but 0.15 copper with 0.1 nickel plated steel sandwich was not happening at all with the red, and had about a 30% success rate with the purple.
The red had about a 30% successful weld rate on 0.1 copper, 0.1 nickel plated steel sandwich with a 99 millisecond pulse. The purple had a 100% success rate on same at 85 milliseconds. I switched out the 10awg on welding pens to 8awg, and got this down to 70 to 75 milliseconds.
I’d like to do 0.15 copper, 0.1 nickel.plated steel. I think a better weld Lipo, or a second in parallel would allow it.
I tried a third chePo spot welder, black circuit board. Same leads to and from as purple and red. Maxxed out it could not reliably do 0.15 pure nickel.
I tried it with 2 large 6v AGM Lead acid golf cart batteries in series, and it went full spark throwing machine gun on me, tried to drill a hole into the battery can. Mosfets shorted closed.
I think there is a goldilocks sweet spot on weld battery size/power with these cheapo spot welders. Too little will definitely fry them. Have not tried the big AGMs again as the weld battery.
Obviously it is far better to get a malelectics.or Kweld or Glitter. These cheapo welders can be more miss than hit and might even be dangerous.
My black welder browned my underwear.
Huh. Neat, maybe i will have to do this, buying a budget one seems like a huge hassle in comparison lol. How easy is it to use? I don’t want to be the idiot that blows it up 
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Gen2 stubby, sky is the limit. P30b should be a good bump for the short term. I saw some 3p enclosures on Ali that can do something wild. 3s3p p30b. We should see tabless 18650s in the near future too.
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Oh, torque test channel has a video with some hotrod batteries and a gen2 stubby. Whatcha using it for? I use mine with a 2.5HO for automotive shenanigans. I have a 5.0 but don’t like the bulk
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Getting into working on my car, since i finally have one worth modding I saw the 3P enclosures, but they definitely are a bit too bulky. I think 3S2P of P30B should be plenty
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Post 58 has a yt video link to TTC, where there are modded Milwaukee packs.
3s2p of P30b should be a beast, if the specific tool can take advantage of it.
My old 10s1p AA 12v nimh electrolux vaccuum cleaner was an absolute beast on an 18v Ridgid pack, but woukld not fire up unless it was under 19.4v, and it fairly recently burnt out, the motor still hot enough to burn my fingers after a non rushed disassembly.
Should be easy enough, it’s the larger flipsky one. It has the stuff like a short early pulse for cleaning the connection, triggering automatically, with the foot pedal or with the pen that holds the electrodes if you aren’t using the handheld probes but uses milliseconds instead of joules.
It needs 12v LiPos or a car battery on an xt90.
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Thanks for clarifying on the VTC6, I saw a few places selling them as 30A cells but only tested up to 15A.
And it’s interesting P28B are for sale on Nkon rated to 10 more amps than the P30B I just thought if it’s accurate it’s worth 200mah.
Considering the difference between voltage over p groups, those which completely discharged had significantly higher self-discharge rate/capacity.
It is almost the same as build a pack with different cells in different p-groups.
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With the storage being for so long, the cells being essentially empty (big voltage change for small charge drop), and all with slightly different capacities, I’m not sure we can say there is a big difference in the self-discharge rates.
IMO it’s not nearly that severe a cell-to-cell difference and I don’t think we can say it’s unsafe. Not great, certainly, and let’s retire the pack. But I think we need to see or know more before we can say unsafe.
And it’s inevitable that normal cell aging causes some differences in the IR and capacities of the different p-groups, leading to an unbalanced pack as you discharge down further and further. It’s a normal part of how a pack ages and is what the BMS is designed to handle.
Building a pack with different cells in each p-group is no problem if a properly working BMS is used. You’ll be limited by the lowest capacity/poorest performing p-group but that’s not a safety issue.
But I hear what you’re saying, it’s certainly always best to be very conservative when it comes to pack safety…retire the pack.
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