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Old 09-19-2005, 09:31 PM   #1
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Angry Soldering Negatives On New Packs

I haven't been able to find any help on this subject anywhere. Maybe someone here knows what's going on.

I'm experiencing a strange phenomenon when I try to solder up a batt pack. I'll get straight to it...has anyone had problems soldering battery bars to the negative side of a cell? I can make every positive joint perfectly if I do it before the negative, and they turn out smooth and flawless but the negative simply won't get a good flow.

I'm growing frustrated by this as I've ruined a perfectly good pack of cells because of it.

I'm no stranger to good soldering joints but this is my first, allbeit unsuccessful attempt at a batt pack.

Am I missing somthing? My Iron heats well (weller 75w), roughed, cleaned, heated, tinned parts resulting in a good flow on pos, absolutely dismal on the negs.

Look at your packs, do they vary between pos and negs?

WTF? Can anyone help me with this? I refuse to start a new pack of cells till I get this resolved (do you blame me?).

***Thanks in advance to all who reply***
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Old 09-19-2005, 09:43 PM   #2
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I think it mainly deals with the surface area difference between the positive and the negative. The size of the positive end cap is very small compared to the negative, this is why I say that it is related to the amount of surface area. I also can make a great looking positive solder joint but my negative solder joints are ussually off center and not perfectly round like the positive.
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Old 09-19-2005, 09:55 PM   #3
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Thanks T.

I thought about that too so I tried a broader tip to expand the area being heated to no avail.

Got any other work-arounds? anyone...? anyone...?

PS The best results I've found was using dual irons. This method is far from easy (due to my lack of a 3rd and 4th arms) and the results are still sub-par at best!
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Old 09-19-2005, 10:39 PM   #4
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Do you have an adjustable iron, for temperature I mean. I was having this problem too. I just turned up the iron temp and it made it alot easier and the solder flowed much better. I have some IB3800 cells and it also seems that the grade of metals is different form the negative end to the positive button on the opposing side, the texture seems different. I don't know if it has anything to do with it but its just my observation.
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Old 09-19-2005, 10:47 PM   #5
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Quote:
Originally Posted by WailinOnYa
Do you have an adjustable iron, for temperature I mean. I was having this problem too. I just turned up the iron temp and it made it alot easier and the solder flowed much better. I have some IB3800 cells and it also seems that the grade of metals is different form the negative end to the positive button on the opposing side, the texture seems different. I don't know if it has anything to do with it but its just my observation.
Thanks...
my buddy has an adjustable temp station but I don't. I'm plugged in straight so I'm pulling 75watts to the tip!

STUPID Q: A station won't bring the iron hotter than it's rating will it? I should think not.

thanks again
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Old 09-19-2005, 11:07 PM   #6
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did you try scuffing the area where you are going to solder. are you using 60/40 rosin core solder. are you tinning the negative side of the battery before you put the bar on.
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Old 09-19-2005, 11:13 PM   #7
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Before you "tin" the negative battery side with solder, use some light-grit sandpaper on the end. I push the sandpaper into the cell with my fingertip, and rotate the cell to get a circular section prepped before I apply solder. This should help eliminate the ugly solder-blobs.

Dont put too much heat onto the cell when soldering. Try to get the surface area hot enough to do the job quickly.
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Old 09-20-2005, 09:29 AM   #8
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ori ive had great luck with a dremel and a cutter/sanding tip for scuffing the surfaces, just hit it LIGHTLY, not to create hot spots. works great!
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Old 09-20-2005, 10:38 AM   #9
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I've had the same problems as you with soldering the negative ends.

The problem isn't the wattage of the soldering iron, but the head. You need to use a very large soldering tip, allowing it to store more heat.

I tried using a 45Watt iron and a regular tip but couldn't solder them. Then I installed one of those "hammer" heads and was able to solder the negative ends as if they were a small 20 gauge wire. People have also had good experiences with the large chisel type heads too (not sure about the dimentions, but I the bigger the better).
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Old 09-20-2005, 10:54 AM   #10
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i've used a weller 45w iron to put packs together for years without problems, what kind of solder are you using? that Dean's (or othe brand of silver solder can be a little more difficult to work with). Get radio shack electrical solder 60/40 normal solder. Scratch the ends of the battery ends with some sandpaper (basically your removing the oxidation), or a dremel (don't over do it, just where the battery bar is going). Lay the battery bar on a file and file the battery bar's end flat so that a nice flat surface will make contact with the battery end (as well as removing more oxidation). The bars are stamped with a punch which leaves the edges higher than the center, those edges hinder good heat transfer. Use a nice clean fat chisel tip (weller 45w iron can do the job fast), and make sure the tip is tight in the soldering iron barrel and that their is no corrosion in the barrel preventing good heat transfer. setup your batteries in a Dean's Speed Jig and there shouldn't be any problems as long as your bars and cells are preped and your iron is in good shape.
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Old 09-20-2005, 05:08 PM   #11
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I had the same problem when I first started to build packs. After sanding the cell end put some solder on the end of the cell before putting on the battery bar. This end my problems of soldering packs.
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Old 09-20-2005, 07:06 PM   #12
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WOW! There's alot of good ideas in those posts! I'm used to scuffing with my dremel and a diamond cut-off wheel lightly tap, tap, tap, in different directions. Then I take a wire wheel with a little flux to clean. I like the sandpaper in a circle method...seems so simple and lo-tech...no wonder I didn't think of it.

I use 60/40 ros core radio shack solder or silver solder, deans battery bars (w/ +- punchouts) 12g silicone, deans ultra conns, and a deans speed jig minus the bar holder downer thingy

Nothing too out of the ordinary.

In all your experiences, are these poor results simply a matter of surface area? because it seems I have the same probs when I try to join the pigtail to the neg bar when the bar's already (somewhat) joined. and as you know, those are 2 significantly smaller areas.

Thank you all for the outstanding replies. and please if you can think of anything else post it as I will keep checking in and working on these destroyed cells till I get it right.

~~THANKS AGAIN~~
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Old 09-20-2005, 07:13 PM   #13
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make sure your using a chisel tip. (screwdriver looking tip) the thicker tip will hold more heat.
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Old 09-20-2005, 07:22 PM   #14
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Quote:
Originally Posted by baih
make sure your using a chisel tip. (screwdriver looking tip) the thicker tip will hold more heat.
Great advice! I think I'm going to shell out for another quality iron so I can accomodate a larger chisel tip. Right now I'm using my trusty 75w weller gun. Maybe it's just not serving the purpose for me anymore.

any advice on a new brand? Money is not a factor, I'm already in the doghouse with the wife. might as well get as much as I can before I start spewing sorry's to her. (tis better to ask for forgiveness than it is to ask for permission).
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Old 09-20-2005, 09:12 PM   #15
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Don't get me wrong, my solder joints have rarely come loose. I refer to my observations to what the solder looks like when tinned, not their holding strength. It is no where near a round or clean looking as does the positive side does. I also do like you guys suggest by scuffing the cells, I have also found that I like using Radio shack solder over deans for it has a better holding strength(just has a higher melt point though).
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