Pure nickel strips for battery pack

[Polaris steve]

I will attempt my first battery pack build.
The pure nickel strips on ebay offer , .2mmx 8mm. Will this work? Or should I get a different size.
Thank, in advance

 

[tomjasz]

I will attempt my first battery pack build.
The pure nickel strips on ebay offer , .2mmx 8mm. Will this work? Or should I get a different size.
Thank, in advance

Are you welding? Some eBay China source sell steel coated with nickel. Coated with 100% nickel. I have a kilo from 5 years ago that is 100% Nickel (coated steel)


Here's a better source of materials and better advice.

18650shrinkandcellholders.com

If you're soldering I'd use "goot wick" and be darn quick!

The latest Vruzend kits are an excellent option.

USE COMMON SENSE. We're messing with substantial power. Kentucky Fried Fingers aren't uncommon!!!

18650 battery pack build Kepler style

The following build was documented in pieces through my latest bike build thread and as such I thought i would consolidate the battery side of this build as one thread and in the most appropriate section. The aim for this build was was to build and 18650 pack that looked like it belonged on the...

endless-sphere.com

 

[Polaris steve]

Thanks for this,
I was thinking of spot welding.
Are you familiar with spot welding? If so, what amount of amps are needed ? There is a spot welder on eBay for under $100. Not sure if it will work. That is why I am doing research. We have 3 ebikes so I am planning for the future, batteries are so expensive.
Thanks

 

[tomjasz]

eBay versions may be OK if you’re an electronics educated fella. Otherwise, I’d stay away. Look at Kweld from Keith’s site. There are others may be cheaper but lack any support. If you use Facebook there a couple of 18650 cell oriented pages.

My first welder was a Sunnko. Nothing but problems. Kweld has a great following on endless_sphere. Kweld has gone up in price but has improved steadily into one of the best! Best of all there's lots of support online!

Another alternative and lower-priced is the Arduino version.

If you don't have Micah Toll's battery building book be sure to get it It's invaluable! Absolutely indispensable!

 

[Polaris steve]

Thanks again,
I watch many, many videos by Micah Tolll, his are outstanding.
I am an retired electrical contractor, so I am somewhat comfortable with this process.
I will check out your suggestions.
have a grea day

 

[Scott Adams]

Second what Thomas has said, steer clear of any of the Chinese welders such as Sunnko.

The Endless Sphere forum has an ocean of postings on spot welding batteries.

I recommend using the nickel strip which has small slots cut into it. The welding heads are placed on either side of the slot, this forces more of the welding current to flow through the weld site.

I used this Sunstone welder for my most recent packs built of Panasonic PF cells. You can see the nickel with the tiny slots in the lower left of this photo. Sunstone makes nice welders, but finding them at a reasonable price is hard.

Kweld is probably the best option right now for home building.

 

[Polaris steve]

Thanks Scott, I have checked out online for the last 2-3 hours the different welders.
the least expensive is the sunkko 737g from eBay, free shipping and free returns.
I will only be making 2-3 batteries, and if it doesn’t prove to be worthwhile, I can send back.
does it have enough power for that?
your input is much appreciated. Thanks

 

[Polaris steve]

Have you ever used this?
18650 18650 Battery Box Assembly Welding DIY Mini Battery Spot Welder Portable

 

[Scott Adams]

There are a large array of inexpensive spot welders available from ali baba, etc. I recall early ones that used a microwave oven transformer to generate huge currents and low voltages.

I have not used any of these, they might make a spot weld, but are unlikely to make quality repeatable welds across a range of materials.

 

[tomjasz]

Thanks Scott, I have checked out online for the last 2-3 hours the different welders.
the least expensive is the sunkko 737g from eBay, free shipping and free returns.
I will only be making 2-3 batteries, and if it doesn’t prove to be worthwhile, I can send back.
does it have enough power for that?
your input is much appreciated. Thanks

Are you sure you can send it back? If it's from a shipper in China you're stuck unless they grant a return, and you pay an exorbitant shipping fee.

Take it from fellas before you and stay clear of Sunnko. The failures outstrip the successes. Just my 5 years of experience with 3 welders, Kweld, Sunnko, Arduino, and the JP welder also on Endless_Sphere but discontinued.
JP made the details open source. Arduino is the most reasonably priced kit.

Have you ever used this?

18650 18650 Battery Box Assembly Welding DIY Mini Battery Spot Welder Portable

Unless you can find some reviews you will be on the bleeding edge. I guarantee these cheap welders have funky soldering and super cheap PCB.

I never quite understand why fellas new to the process want to throw away the experience of those before us. It's now massive, but the Kweld and JP threads have scores of failures with junk welders.

I see now that China has jumped in with all kinds of cheap welders. All low end copies of the welders I mentioned.

Personally I prefer the Car Battery types, as managing LIPO batteries is a potentially dangerous adventure. AND requires another charger.

 

[Polaris steve]

Thanks for your concern, I saw Micaha Toll from school using what looked like the Sunkko 787a he didn’t say bad things about it. So i figured it is ok.

 

[tomjasz]

Thanks for your concern, I saw Micaha Toll from school using what looked like the Sunkko 787a he didn’t say bad things about it. So i figured it is ok.

That's an older welder and lots has happened since then, but as usual here some days an n00b knows better.

Here's a quote from Karl at electric bike blog posts on Micah's book.

"This is the $200 spot welder I settled on using from eBay. Cheap Chinese crap, but is sort of works, if you don’t mind replacing melted fuse holders. The first one I got for $100 and died before my first pack was complete."

Those are 3-4-year-old posts. Lots has happened since then, I shared those improved welders with you, but it's your money and house.

All the best! Let us know how it works out.

 

[Polaris steve]

That's an older welder and lots has happened since then, but as usual here some days an n00b knows better.

Here's a quote from Karl at electric bike blog posts on Micah's book.

"This is the $200 spot welder I settled on using from eBay. Cheap Chinese crap, but is sort of works, if you don’t mind replacing melted fuse holders. The first one I got for $100 and died before my first pack was complete."

Those are 3-4-year-old posts. Lots has happened since then, I shared those improved welders with you, but it's your money and house.

All the best! Let us know how it works out.

Thanks again.
after all the reading and videos, I’m thinking maybe I should just buy a battery pre made.
I have 2 Polaris vector bicycles, one works the other doesn’t, I haven’t figured out what is wrong with it. So I am thinking of buying a conversion kit either a 48v x 1000w or 48v x 750 w
your thoughts on this.

I really appreciate you taking the time, you’re a good guy

 

[Polaris steve]

Another question, how much amp hour min should I get?

 

[tomjasz]

Another question, how much amp hour min should I get?

As much as you can afford! I don't know your planned kit but 36V is available in shark cases with 17Ah 48V as well.

And yes, getting into configuring and welding won't save you anything if you're just going to build a couple of batteries. AND there are a LOT of pitfalls. Up to and including a battery fire.

 

[Polaris steve]

Thanks
you have helped me more you know, I do appreciate it.

 

[tomjasz]

Thanks
you have helped me more you know, I do appreciate it.

Thank you! I do try my best to share the experiences I've had. It's gratifying when I can help someone NOT making all the mistakes I made!

Have fun,

TJ

 

[Nearchos]

I have a question about the thickness of nickel strips.

 

[Nearchos]

Let's assume you have a battery pack in a Reention SF2 case, charging a 36V 350W Bafang G070.350.D hub motor.

The battery pack provides 36V 24.5Ah with LG 18650 3500mah cells arranged at 10S 7P.
With pure nickel sheet connections, insulated cell groups & insulated BMS.

Questions:
a) how thick should the pure nickel sheet connections be? Ideal conductivity scenario, forget the cost. Is 0,15mm enough?

b) can it be argued that if the nickel sheet connections are thick enough, with a sophisticated BMS and good quality cells (not Samsung though), it is not necessary to install a second set of wires for each cell group to be individually measured & balanced for charge?

Can thick nickel sheet connections make up for a second set of wires balancing the charge across the pack?

c) is a second set of wires for each cell group to be individually measured & balanced for charge indispensable when the pack is at 36V?
My chinese pack builder asserts that modern cells are very consistent and it is not necessary for such a low voltage...

 

[Nearchos]

@ ProphetZarquon
@ tomjasz