Got into some spot welding on my first pack recently and I'm thinking about the pattern for soldering on the 6 gauge wire and also for attaching the two parallel fused nickel strips. Opinions on which of these two photos would be better, or any adjustments to the bridging nickle strips (longer for example)? Also, any advice for soldering the 6 gauge - particularly the interval?
Greenhouse Backup Plan
- Thread starter 2Lime
- Start date
New & used Batteries, Solar, accessories, LifePo4 cells & more 5% Coupon "Powerwalls" www.batteryhookup.com
Korishan
Administrator
- Joined
- Jan 7, 2017
- Messages
- 7,999
I would say the left one, the 2 parallel loops of equal size, would probably be better. Altho, to be completely honest, unless you are pulling max amps, probably wouldn't make a big difference on either design considering how much nickle plating there is to distribute the loads.
For the bridge between the two, I'd say put a nickel strip between each cell, not every other one like you have in the images.
For the bridge between the two, I'd say put a nickel strip between each cell, not every other one like you have in the images.
OffGridInTheCity
Moderator
- Joined
- Dec 15, 2018
- Messages
- 3,104
I use lugs on my 6 awg twisted copper bus. 2 x 6awg just happen to fit nicely into 2awg Lugs for crimping but you can buy lugs of any size - https://www.amazon.com/gp/product/B06XKY75XJ/ref=ppx_yo_dt_b_search_asin_title
Then I just flatten copper pipe, cut and drill holes for bolting things together. The copper bus bars bend/flex quite a bit so the flattened copper pipe w/holes doesn't have to be 'machine perfect' - hand cut/drilled works A-OK.
Haven't had any heat issues or bolts coming loose and I'm over 6 years of operation now.
Then I just flatten copper pipe, cut and drill holes for bolting things together. The copper bus bars bend/flex quite a bit so the flattened copper pipe w/holes doesn't have to be 'machine perfect' - hand cut/drilled works A-OK.
Haven't had any heat issues or bolts coming loose and I'm over 6 years of operation now.
Last edited:
Had a bunch of 12 and 10 gauge wire so I tested out some methods of combining to make 6Ga. The braided is nice because it doesn't get lumps (two 10Ga and a 12Ga) but it proved too difficult to solder, the kinda lumpy twist is also two 10Ga and a 12Ga, and the smooth twist is 4 12Ga wires. For the end connections I cut 3/4in long rings from a copper pipe, sliced them on one side with a bandsaw, pried them open, hammered them flat, and wire wheeled them smooth. Then made a template with some nails and a block of wood so that I could solder them together. Sure went through a lot of 63/37 Rosin core .031mm solder. Also built a solder/rosin fume extractor out of an old fan, some flexible drain pipe, and a wooden spool end. Covered the sides with polycarbonate and/or acrylic sheets, including an extra bit on the end to protect the connections. Used 1/4in oak dowels and galvanized push washers to hold the sides on.
View attachment 20241123_115028.jpgView attachment 20241008_201951.jpgView attachment 20250103_062645.jpgView attachment 20250105_091353.jpgView attachment 20241120_182227.jpg
View attachment 20241123_115028.jpgView attachment 20241008_201951.jpgView attachment 20250103_062645.jpgView attachment 20250105_091353.jpgView attachment 20241120_182227.jpg
kje
Member
- Joined
- Apr 12, 2022
- Messages
- 263
I imagine that the solid core wire wouldn't need nearly as much solder which would be nice, but I didn't have any available to try out. Solid would also avoid the random little wires trying to frey at the ends too. I'm thinking that solid would be harder to bend though, and more prone to the solder joints cracking since there would be little flex. I would think that both would work fine though.
Two batteries built (14s120p with one spare pack for each). Ordered the diybms via JLCPCB (may put a few details from that over in Wolf's thread). Boards arrived and look good, waiting for a few other parts to put it all together. Found a couple boxes of 4/0 (quadruple ought) lugs at a local reuse store for super cheap, bought a crimper (TEMCo TH1818), and got lucky again at the scrap yard - they sold me a bunch of short pieces of 4/0 flexible (mostly tinned marine grade) wire at about scrap price (about 1/3 the cost of new). Had to buy a bigger wire cutter for these (TEMCo TH0001). 4/0 wire will be used for the pack interconnects. Likely overkill on the wire, but won't hurt the efficiency.
kje
Member
- Joined
- Apr 12, 2022
- Messages
- 263
That's very nice buildt packs. Great to have overkill wire!
Had some more luck at the scrap yard. They had a whole pallet of power tool batteries, mostly Milwaukee and some DeWalt. I bought 13 heaping 5 gallon buckets full - that's about 500 pounds for 50$, pretty good at 10 cents a pound. About 10 percent rusty - those will get recycled again, another 10 percent just had cracked shells (warranty returns) so I'm in the process of swapping those out with other shells for normal use. Found approximately two dozen working Milwaukee packs ranging from 2Ah up to 12Ah. Most of the rest will be disassembled for the cells. Typically INR18650-25R Samsung cells in the 5Ah packs (the 4 Ah packs have 2amp cells, and the smaller packs are even less) - 21700 cells on some of the big packs.
Some of the 21700 form factor cells have a very thin sprayed on glue coating (like circuit boards have sometimes), it comes right off on some of the cells but on the others it is very stuck. I need to clean it off for charging, and was thinking maybe a scotch-brite pad for the ends? Anyone ever dealt with removing very thin clear spray on glue?
Some of the 21700 form factor cells have a very thin sprayed on glue coating (like circuit boards have sometimes), it comes right off on some of the cells but on the others it is very stuck. I need to clean it off for charging, and was thinking maybe a scotch-brite pad for the ends? Anyone ever dealt with removing very thin clear spray on glue?
kje
Member
- Joined
- Apr 12, 2022
- Messages
- 263
Wow that's a lot. Is it really possible to buy this from the scrap yard?
Yeah, I was very surprised. The first guy I talked to said that they didn't even have any batteries, but I think he was just confused about what I was looking for. Luckily the next guy I happened to ask knew what I meant. It's crazy whats out there, especially if you can find a place that will let you just wander around and look. I almost bought the whole pallet but I'm glad I didn't, after I put the first 1/3 or 1/4 of the total pallet in buckets I could see that the rest was a mess of other things like nicads, lipo, and other pouch style batteries.
They also got in a huge load (a trailer and truck full of barrels) of 14 AWG to 1 AWG tinned marine grade wire (it's amazing what folks will scrap) as I was leaving, and I need to decide if some of that's worth buying since it will be near scrap price too.
They also had some of these but they seem relatively low capacity unless you can get a lot. Fun fun.
They also got in a huge load (a trailer and truck full of barrels) of 14 AWG to 1 AWG tinned marine grade wire (it's amazing what folks will scrap) as I was leaving, and I need to decide if some of that's worth buying since it will be near scrap price too.
They also had some of these but they seem relatively low capacity unless you can get a lot. Fun fun.