Spot welder / lithium packs thread. Recently discovered that

>>1043705
Smh. 4got link. http://m.ebay.com/itm/50PCS-5800mAh-Li-ion-18650-3-7V-Rechargeable-Battery-For-Flashlight-From-USA-/111849969876?nav=SEARCH

Looks pretty good for a power cell, transformer could give it many uses

File: FSNBWHIHAQ2TMS2.MEDIUM.jpg (75KB, 620x620px) Image search: [Google]

75KB, 620x620px

King of random spot welder.

Mine will be similar but not as fancy.

Probably run a foot switch for power and 2 hands use for build packs.

Anyone ever build there own packs?

Pic related.


https://youtu.be/vrlvqib94xQ

>>1043709
Kinda what i was thinking. Mostly diy ev stuff. Lawn mower, bike, scooter.

I am an amerifat so the weight and performance would greatly increase my vehicles.

>>1043705
I know it won't help you now, but 'the gold standard' in BMS for hobbyiests is in testing right now and should be out within 6 months. I'll post here as soon as it's done. In the mean time, most Chinese solutions are half-trustworthy, so check on them periodically.

As far as spot-welding goes, I've done it a fair amount and I still prefer soldering packs with a big-ass iron, some copper braid, and lead-free solder. Sure, some amount of capacity is lost in the soldering process from heating of the cell, but this gets minimized with practice. Almost all DIY spot-welder solutions I've seen and used have given welds that are inconsistent at best, and you'll end up spending more time on the welder than actually making a pack. Soldering iron done right is cheaper and stronger, with capacity for higher discharges.

The big thing you want to watch out for with batteries is the third variable, discharge rate. With Lithium Ion, it's usually quite low meaning that you can only pull a few amps from each cell before damaging it. With Lithium Polymer or Lithium Iron Phosphate, you can get discharges in the tens of amps, with the "gold standard" being the A123 26650's capable of discharging up to 80A burst each. You can still use poor discharge cells for heavy loads by putting a lot of cells in parallel, which is especially important in stuff like e-Bikes.

>>1043761
Actually does help a bunch. Reason for spot welder is cheap diy. Am fuckall broke for 3 months. Planning a 2,000 watt scooter. I am a fat and probably build a used 20-30ah 48v setup. Havent got the frame mocked up or measured for packs yet.

Thank u for the tips.

>>1043708
>no brand
>current max capacity of actual trustworthy brands is around 3500 mAh
Avoid like the plague.

>>1043711
>2:19
>Orbital sander

>>1044247
Lost. Good catch

>>1043711
Spot welders for batteries are a little different, if you try to weld between the terminals you'll kill your battery. Gotta weld from the sides of the same terminal, its a pain to nigger rig but its still doable.

>>1043761

Most batteries have terminals made of metals (stainless normally) that are a pain in the mother fucking ass to solder properly. You gotta put a shitload of high temperature flux on it and then scratch the crap out of it (under the flux) and solder (under the flux). It fucking sucks balls. Also silver solder works like 90x better than SnPb solder on stainless.