Battery spot welding question.

[Brian Ski]

It has been a while since I hung out around here, but come back when I have a question.

I am looking for a spot welder for 18650 batteries and similar. They have a bunch of different kind of units on the market. I do have an Everlast 200DX that I bought some years ago. Has anyone done any battery spot welding with one? Is it recommended? Or any ideas??

[zoama]

I don't know about using the 200DX. It would need a timer in milliseconds and a custom set of spot welding leads.

I think you'd be happier using a ready made machine like this one on amazon https://www.amazon.com/dp/B09FJQN7DT/ or something similar along with nickel fuse roll from batteryhookup.com

I've built lots of lithium battery packs but I tend to use Li-Po cells from medical equipment for their higher energy density and solder connections.

Here's a 110ah 36v nominal pack I built to power my trolling motor 42v - 30v. It measures 9"x9"x9" without it's aluminum case. Each of the 250 cells have a 4amp bms and are rated 4.4ah from 3-4v. The strap I use as a buss bar is rated for 105a.

[Brian Ski]

I could deal with custom leads, but wasn't sure about timer. I looked at a few of the welding machines on the bay and zon. Reviews are all over on the cheap Chinese machines, and unsure about battery operated ones.

Do the LI-Po cells charge the same or do they need a completely different charger? (In other words are they swapable with Lithium Ion?)

I am trying to keep tool buying to a minimum since I have quite a collection already. But it would not hurt to rebuild some battery packs. I have a $100 pack that has bit the dust and always like to fix things. Guessing it uses 5 cells and it is a 2.0 AH.

Glad to see you are still around !!!

[zoama]

Yeah li-po uses the same charger as li-ion. Battery powered spot welders are the way to go since they get you around the feedback problem of transformers with leads that are too long damaging their control boards. I'm only referring to battery spot welders not any Everlast products.

I check battery hookup every day for deals because you never know what you'll find. I made a post a while back about their disposable battery deals. https://www.everlastgenerators.com/f...-CR123A-AA-AAA

Glad to see you still around also. I wish this forum had more traffic.

[Brian Ski]

I ordered one of these... Price was cheap. It did not have a lot of reviews. But the ones it had were good. It looked like higher current and slightly less features. I am not sure how much I will use it. I also grabbed some .15 x8mm nickel roll. Someone pointed out the nickel plated steel is not as good.

I still have some questions on battery packs. They say to use High current batteries for tool packs. Not sure exactly what to look for. Also read not to use protected batteries for the packs.

https://www.amazon.com/dp/B0CB3KWD24

[zoama]

That spot welder looks ok.

You can look up the specs on any cell by searching it's part number. Many low end 18650 cells can only discharge at 2 or three amps.

The best high capacity 18650 (LG MJ1) has 3.5ah capacity and can discharge at a constant 10a.

18650 "power cells" normally used in tool batteries and vape pens can discharge at 15-30a but have lower capacity, about 1500-2000mah.

Here is an excellent source for 3200mah cells that can discharge at 10a. $1 per cell in a pack of 70. Not bad for new never cycled cells. https://batteryhookup.com/products/n...650-33v-99-kwh

[zoama]

Just remember to fully charge each cell before building a pack and it's best to let them sit a few days and recheck the voltage to be sure their internal resistance hasn't gotten too high. Any cells that lose voltage after three days should not be used to build a pack but can still be used individually.