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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: making a battery pack?
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Author Topic: making a battery pack?  (Read 6281 times)

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Offline Neon711

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making a battery pack?
« on: July 12, 2014, 06:57:45 AM »
    I want to use 2 18650 vtc5 in the mod i am building. Problem is im a few milli to small to fit batt tray. Is it ok to solder direct to the batteries and wrap them in heat shrink so the tray doesnt have to be used? Im good with the iron so over heating the batt shouldnt be an issue, however i want to know from the pros wether its safe to do. Thanks in advance.

Online Breaktru

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Re: making a battery pack?
« Reply #1 on: July 12, 2014, 07:23:42 AM »

Offline Neon711

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Re: making a battery pack?
« Reply #2 on: July 12, 2014, 07:36:51 AM »
Thank u....thats what i was hoping to hear. I think i will still have gloves on and an extinguisher near by

Offline CraigHB

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Re: making a battery pack?
« Reply #3 on: July 12, 2014, 11:47:30 AM »
It's possible, but it's tricky.  You have to be really careful not to get the cell too hot.  Use a high temperature setting with a contact time short as possible.  Buff and flux the area to be soldered beforehand.  I use Scotchbrite since it's non-metallic and works well.

After I made that post before, I later realized I was damaging the seal on the top cap a little bit.  So, it's even more tricky than I initially stated.  However, I'm soldering the negative side up by the top cap.  If you solder the negative side at the bottom, the cell will be more tolerant.  In any case, that top cap seal is the most heat sensitive part of the cell. 

There's a plastic film inside the cell insulating the plates that is also heat sensitive.  You don't want to solder on the side of the cell unless it's at the top or bottom away from that film.  If that film gets damaged the cell will short internally and you don't want that.

Oh, BTW, the proper way to make battery packs using the round cells is by attaching tabs with a capacitive spot welder.  You can Google it and find a bunch of articles on how to make a welder for cheap using a couple big capacitors.  People do that a lot to make packs for electric scooters and stuff.  If you plan to make a lot of packs or some big ones, that's the best way to go about it.


« Last Edit: July 12, 2014, 12:07:53 PM by CraigHB »

Offline Neon711

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Re: making a battery pack?
« Reply #4 on: July 12, 2014, 12:35:16 PM »
Thanks again. You are just a fountain of knowledge. I dont have many to do. Just two of them. Just want to take advantage of all the materials i have.

Offline CraigHB

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Re: making a battery pack?
« Reply #5 on: July 12, 2014, 05:15:38 PM »
Oh one other suggestion, at one time I looked into using a tin-bismuth solder which has a considerably lower melting temp so you don't need to use as much heat.  It's 138C versus 183C for sn63/pb37.  I never tried it since I've managed to use the sn63/pb37 without issue.  Might be something to check into.

Offline djboa

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Re: making a battery pack?
« Reply #6 on: July 14, 2014, 03:29:09 AM »
the easy solution is to buy batteries with tabs already soldered ... soldering your wires to the tabs is not as critical as directly to the batteries, plus it is as short as possible.

Offline Visus

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Re: making a battery pack?
« Reply #7 on: July 14, 2014, 10:37:08 AM »
OT/
I've had chemical reaction with lipo's and soldered tabs exposed to air.  Maybe its just mine, but both of my lipos had the same reaction but the one end taped really good did not.  There were small salt like crystals around the join on mine I am using 67/37 kester mild flux solder.  I have no idea why its happening it may be a reaction from the electrical tape no kapton.  I used kapton on the good end none on the bad IDK its strange.  I salt watered and threw those batts out they were starting to have a slight swell on the very endcap I push/puckered it in, it pushed back.  Those round lipos have so very small solder tabs I really do not think they are meant to be soldered..  Definitely capacitive welded on them and even though they say 15A+ I dun think they can handle their own limits with that small of a tab..  Im leaving lipo's alone until I make a welder and are definitely kapton sealing them in well after weld..  They did do 300% better than 14500's I get the reg whine now trying to vape same 1ohm atty I vaped  no hum with the lipo's on the 4050c mods..


Good luck if you solder the 18650 I would go with pre tabbed myself they make the sony's and lg's  in pre tabbed I have seen them on ebay..

Offline CraigHB

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Re: making a battery pack?
« Reply #8 on: July 14, 2014, 01:08:21 PM »
Yes, you can get the big name 18650s with tabs so that's the best way to go.  I forgot about that so good thing you mentioned it.

I haven't had any issue with corrosion on my soldered tabs.  One thing I can think of is that activated rosin flux is somewhat corrosive.  It has to be cleaned off with rubbing alcohol after soldering is complete.  There are no-clean fluxes that you can use that don't require cleaning, but nothing works as well as activated rosin flux.  I use the RMA type that is mildly activated.  It's not as corrosive, but still works well.  Sometimes you can't get all the flux off completely.

Juice is also rather corrosive to metal.  If your mod is allowing exposure to vapors to any extent inside, that could be a cause.

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