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Old 07-12-2008, 10:50 PM   #1
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Default help building battery packs

ok wires are easy but i just cant figure a way to get battery bars on the batteries. i have 60/40 solder, gel flux, and access to an adjustable 40W iron, a 60W iron, and a 120/400W craftsman "gun". i tried putting flux on the battery then dropping a tinned and hot battery bar on it. i tried tinning both the battery and bar. could i maybe just put an untinned bar on an untinned battery, put some flux on them and then just add some solder. i would like to be able to get the bars flat on the battery without overheating the cell.

last time i build a pack i got the batteries damn near boiling hot and that cant be good.

is there a certain charge state the batteries should be in that helps prevent heat damage to the cells?

if only super glue was as conductive as solder, then these packs would have been done 2 weeks ago.

oh and i did a forum search and couldnt find anything from this year. is there maybe a thread someone remember that has building tips that some could possibly post a link.
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Old 07-13-2008, 12:14 AM   #2
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I ran into the same problem a few years ago. Try scuffing the terminals (side that face battery), and the battery itself in the places you intend on sodiering with sand paper. This gives edges for the sodier to stick to.
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Old 07-13-2008, 01:39 AM   #3
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- Scuff ends of cells with dremel
- Install heatshrink on each cell
- Glue cells together wish ShooGoo and let sit overnight
- Tin ends of cells with a little solder & 80w iron (not gun)
- Lightly tin ends of the battery bars
- Position battery bar and press down firmly with pliers
- Tin 80w iron with healthy blob of solder
- Apply tinned iron to battery bar until it sinks into position (should be nearly instant)
- Repeat the last three steps until all bars are installed

The bent end bars can be tricky, and it's easiest to solder them while they are straight. Then you can bend them around the ends of the cell. Just make sure to leave a little space off the cell body so they don't cut into the heatshrink and short the positive end out...

BTW: The reason I say "iron" and not "gun" is because the guns are typically only rated for about 30 seconds on, followed by 5 minutes off. They will quickly overheat, and stop working properly if you don't follow those guidelines. Also the Weller 80w "stained glass" iron comes with the perfect tip for doing batteries (and it's cheap)...
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Old 07-13-2008, 01:45 AM   #4
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Get a good quality battery building jig.

Yokomo and Deans make the best ones, they have a little arm to hold the bar in place.

My advice...

DON'T add another wrap of heatshrink (makes fitment harder and increases cell heat)
DON'T use shoo goo (no need as bars hold the pack well enough)
DO use the most powerful iron you have
DO tin the cell and battery bars (no need for scuffing if your iron is up to the job)
DO make sure that the solder "flows" under heat, don't just melt gobs of it on the cells as you will end up with a dry joint which will break apart (although it sounds like you are experienced with soldering already).

The jig makes the biggest difference, turns a 30 minute job into 5.
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Old 07-13-2008, 01:56 AM   #5
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I am for the scuffing the cell ends with a dremel. So many times I have seen packs break apart because the cells weren't scuffed. The only real thing that the scuffing is doing is removing the oxidized surface and giving something for the solder to grab onto. The only time I have a pack break apart is when the solder breaks off the bar.

When you tin the cell, it should be a thin coating, as should be on the bar. With the 80 watt weller, it doesn't take long to re-flow the pre-tinned joints. It shouldn't take any longer than 3 - 5 seconds to completely re-flow the solder. If it does, then LIGHTLY tin the iron.

Something that people always fail to bring up, let the iron recover between joints. It works like this, soldering a joint is actually transferring the heat from the tip of the iron to the joint. Before you can expect it to give 100% to the next joint, you need to let the tip get back to 100%.

Soldering guns don't hold enough heat to sufficiently solder the mass required to join batteries. Use it for where you need instant heat, and something that cools quickly (no mass to hold the heat).

I am also for the extra shrink on the cells. It will protect the oem shrink. I also tape my batteries, I like the matching labels to stay in tact.
I have a deans jig, and will not use any other...
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Old 07-13-2008, 01:57 AM   #6
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i got the venom jig. its alot like the deans one. i couldnt find the deans one anymore (BTW can someone please tell deans that there website is older than the internet and needs updating [ their mini wire is definitely coming sooner than i think because at this point i expect it to be released the day after the universe ends], go check it out www.wsdeans.com )

anyways. keep the tips coming. i think i might go out and get a pack of Duracell's to practice on.
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Old 07-13-2008, 09:24 AM   #7
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shame on the deans deal. they need to grow a brain and put that thing back out

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Old 07-13-2008, 10:55 AM   #8
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Me and a few friends speculated on that one... The connectors they sell by the thousands, the jigs, not so many. With the advent of Lipos it's either not worth another production run, or the mold needs work and is not worth the time for a small production run.

The venom is nice, beware that there is a spot that breaks easily. I have seen a few locally that have broken in the same spot. I am going to the Yoke site to see what theirs looks like...
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Old 07-13-2008, 11:04 AM   #9
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Unfortunately, like most of their parts, no picture. That is what I wanted to see most...

Yokomo USA has them in stock for $20 each and the part number is YT-BJ. I guess it makes sense, last I knew Lipo was not allowed in events in Japan..

Edit: RC Mart was using Javascript to keep people from using their pics... That worked:



It actually looks very robust, unlike the Venom.
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Last edited by timmay70; 07-13-2008 at 11:11 AM. Reason: add info
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