Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Building Solderless battery pack
#21
Yeah.

Well designed springs used for electrical purpose need to have good conductivity along with great mechanical properties.

That means good electrical conductivity is paramount, but also contact resistance.

Here are the rankings in terms of worst to best in material choices:

1. Bare chrome plated steel spring. Bare chrome plated springs are the absolute worst of all. Not only is steel a poor conductor of electricity, chrome is an extremely hard element, meaning contact resistance is a huge problem, even with a very large surface. Would not use, especially since it's that one inside of the holders, both conical and leaf springs. Absolute crap, and would not trust my life with it not to melt at more than 2A.

2. Nickel plated/Gold plated/Silver plated steel spring. This solves the contact resistance problem we have, but electrical conductivity is unchanged.
And making gold plated springs is small quantities(less than 2000pcs) is prohibitively expensive because of the minimum order qty of gold anodes.

3. Any plated phosphor bronze spring. A copper alloy. Any plating will do, as long as it's a decent plating like nickel, because copper tends to oxidize quickly, and plating will prevent this. Other than that, it's the perfect balance between performance and mechanical performance, but most importantly, cost. It's more expensive than plated steel, but less than beryllium copper ahead, and an average of 3x the conductivity of steel makes up for it by a long shot.

4. Nickel plated Beryllium Copper C17530 spring. This is straight up the best all around choice. Excellent conductivity at 38% the conductivity of pure copper, with good mechanical properties assuring almost no plastic deformation. It does cost quite a bit more than phosphor bronze, but 2x the conductivity is still worth it. You can also use a silver plating for a 20-30% cost increase for best performance, but if not needed, it will still work well.

5. Silver/Gold Plated Beryllium Copper C17500. At 45% the conductivity of copper, and a silver/gold plating, this is the choice for absolute highest performance, at the cost of greatly reduced mechanical properties, mainly yield strength. Quite expensive, and not really used unless in very very high performance applications.
Korishan likes this post
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#22
So, basically, contact resistance depends on how much surface area and material hardness.

Mostly material with springs.
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#23
I think it's possible to cheaply and effectively use two separate elements for the spring and the contact. I'll try to take some pics this week.
Reply
#24
Yep. It's quite easy actually, like I did here.



I used phosphor bronze springs for the negative contacts, and brass buttons for the positive ones.
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#25
And butchered the crap outta the holder Tongue But at least it doesn't leak energy now Wink
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply
#26
Yeah. As I posted in before, I had to use acetone and hot glue to get the holders to stick.

I've actually finalized the specs for the 4S2P and 5S2P battery pack, along with hardware.

I now have to find a manufacturer to make tough plastic battery holders.
Korishan likes this post
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#27
I used springs harvested from 6V industrial batteries. Not sure what they're made of.

Reply
#28
Are they magnetic?

If so, they are made of steel.
The power of lithium ion is in our hands!
We'll show them what we're made of!
Reply
#29
Having some ideas adding heatsink to dissipate the heat from the battery. I was considering PC fan initially, but you still need some power to it. 
Heatsink will be more appropriate. I don't see people using it for their pack.. why? Cost? Space?
   
Reply
#30
Why would you need heatsinks to cool the "battery"?! If it's getting that hot, you have another problem to deal with, or you are pushing or pulling way too many amps from the pack
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply


Who read this thread?
100 User(s) read this thread:
daromer, Sean, mike, owitte, Korishan, PAF, Franky Beuselinck, wim, typ49, watts-on, Dan Lim, Stefaan De Ridder, BlueSwordM, idiomatically, ivnz, Geek, mr_hypno, hookemdevils22, David Arnshelm, DarkRaven, Grumplestiltskin, DCkiwi, cristof, CarelHassink, Jensk, karmi27, bigblue, Charly144, djuro, sturgeo, spinningmagnets, jm1, marcin, drchips, Issac, gpn, raul_ap, Chablis_m, Headrc, ionutnegrea, Dala, Redpacket, Ibiza, farmerjohn, choncy12, Bubba, Sholphin02, Walde, MissSolar, Riplash, Maikel, 100fuegos, bukvaahmed@gmail.com, Katarn_89, w0067814, Gummiadler, Sammm, naph, Buzz0515, chuckp, Hector, MGPTWEGB, emuland-metroman, hazSolar, Chass90, kwabdul, Truth, clupton, RayGenWurm, risoman, deniscroombs, Wolf, Lekr, collinkoolen999, camthecam, Dallski, Solalar, rettore, Speicher, Manju18, stevelectric, richie241, engarom, ppavone, ajw22, BmoreThor, RikH, lloulou11, JulianT, hanwen127408, kevinjaye, Maniac_Powerwall, LEDSchlucker, zoookii, bchur83, sparkgap, fannel, andy chalmers, tsmurray, Iker138

Forum Jump:


Users browsing this thread: 1 Guest(s)