How to... Build Stick Packs?

[WillyChang 1814]

Anyone tried building stick packs out of loose cells before?

Just wondering what's the neatest/safest/fastest way to solder the cells head-to-foot.

Thought someone used to make these "corcentina" type battery bars to go between the cells within a stick, but can't find them anymore. Anyone use them before & how are their current capacity?

[TWO STAR 0]

when i used to work at a battery firm,i used to bang out stickpacks all day long....menaughtnus....lol...i used various types of tin or thin stainless for most connections,very simple,but i had a "tabber"

machine,its basically a micro welder.i placed pucks in between each cell to prevent arcking or shorting,the pucks were made from thin

polystyrene.at home here ive tried to make similar stick packs with a slodering iron...lol..that was allot of fun...i actually managed to make it work but it was longer due to the solder on the + & - of the cell.... sanja.

[Twmaster 1]

I make these packs all the time. You need a hammerhead soldering iron tip and a >40W iron. I place the cells on a piece of aluminum angle to hold them in alignment. The trick is tin the cells first then place on the alignment jig put the iron between the cells push the cells to the iron till the pretinned area melts, quickly remove the iron and push the cells together. A couple of points to note. 1. Use only the slightest amount of solder. 2. do not heat for too long. 3. if possible use an insulator on the top of each cell.

Here is a link to a picture of the tip I use (middle of the page):

http://www.hobby-lobby.com/bataccy.htm

I build all my packs for my racing boats so my hammer head tip gets loads of use [8D]

[terry.sc 16]

You can build stick packs with no special equipment, just the soldering iron you use for saddle packs. They can also be easily dismantled if you want to turn them into saddle packs at a later date. For years I have built my packs this way, I would remove the welded tabs and rebuild the packs like this.

I have dismantled a pack to illustrate this, so the pics are not as clear as they could be. Use a solid copper wire, it conducts best and is flexible. Heavy duty mains wiring usually has a suitable core. Solder a length of the wire to one nicad, I tend to solder to the top of the cell first as that is the end that has to have the wire located properly. Attach the wire off centre, as shown here

Then place the other nicad next to it as shown here, make sure the batteries overlap slightly otherwise the wire will stick out of the edge of the batteries.

Now roll the battery over until it lines up with the other battery.

Sleeve the batteries in heatshrink. The battery pack is slightly longer, mainly depending on how neat your soldering is, but it tends to fit inside chassis okay as it does not have the extra length of the moulded ends on standard packs.

[DJTheo 2]

Very good idea [^], just a question, isnt the wire you used in the pics between the cells a bit too thin for RC car use, or does it just show like that on the pic?[?]

Cheers

[BiggusDitchus 38]

The thin wire trick is the best to use, far superior to the little tabs.. the wire when coiled provides a large contact area between the cells.

[terry.sc 16]

The copper wire I use is about 2mm in diameter, which as it is a solid single piece of wire it is more than capable of handling the currents used. When the pack is covered in heatshrink it pulls all the joints together, so there is a direct contact between the cells as well. Never had one fail on me yet, and compared to the standard pair of spot welds this has to have much less resistance.

[WillyChang 1814]

Firstly Thanks for the posts, guys.

TWmaster:- hammerhead iron is good idea... but could be very difficult disassemling those cells again without a blowtorch.

TerrySC:- that skinny little wire is will possibly by offering some resistance, which will create heatspots when the rest of the circuit is wired with 12-gauge. I've been doing same with desoldering (copper) braid, but this adds approx 2mm to each junction.

Spot welds are the same, they don't pass big current all that well. Same with the skinny tinfoil that packbuilders use to interconnect the 2 sticks, they really heat up under load!!

aside:-

Last night I was stress-testing some packs, hooked up to a rig that drains a fully-charged pack in 5 mins. I was monitoring the lot with a thermometer too, and some of those spot-weld junctions can actually get hotter (70-80degC) than the Tamiya battery plug. [:0]

A thin fillet of solder over the bridge helps currentflow greatly. Or just replace it with a decent battery bar.

[RETRO R/C 59]

I have been using the method that Terry has for YEARS - and have never had a problem. This includes competition cells as well.

All experiments aside Willy, everything you try is going to have a disadvantage of some kind........just pick the one that works best for you.[8D]

Cheers

Darryn

[WillyChang 1814]

quote:Originally posted by darryn1

....just pick the one that works best for you.[8D]

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Or hack the Tamiya chassis to take side-by-sides... [}]

[mr_lister999. 3]

Stick packs are a pain in the backside to make. I used de-soldering braid but the pack comes out a bit longer than a shop bought one which means it doesnt fit in some cars. I just thought blow the expence and bought some stick packs. Just did a bit of overtime at work which actually meant less work than modify the packs! I know that doesnt help you but i,m ok []

[Cavscout 0]

Terry,

Thank you for posting those pictures, they are very helpful! I have built a couple packs myself, and even the hack I am, was able to do a decent job just utilizing some soldering skills picked up over the years. I am definatley going to use the method which you and Darryn have referred to with the wire in between cells. Thanks again. I keep on reading articles on people building packs using the "tin, heat and push together method" but as mentioned, very hard to take apart if you want to change the configuration. Thanks again guys.

Scott

[WillyChang 1814]

quote:Originally posted by mr_lister999.

...it doesnt fit in some cars.

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Yes, this is the problem I'm having too. [:I]

The longer packs are a very tight fit across the M03/TL01 and 04PRO; ok on the TA03 though. On the M03 the little angle brackets are stressed and the battery even slipped out once whilst testing on Sat (might have been impact-related too.[])

I think some of the newer cells are just *taller* than 1200s...! [:0]

What I'm gonna try next is... have gotten some very thin & flat battery bars. I'm gonna bend these into "L" shape and stick one end to the +ve. The other end will reach around to the side of the -ve can, I'll just trim the cell's wrap off there.