# Soldering battery packs



## abernat (Jan 3, 2008)

Hi,

when putting together a battery pack from tabbed batteries, do you simply solder the tabs together or bind them together with some wire?

Thanks,
Andy


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## Totalwrecker (Feb 26, 2009)

Bend them together and solder them, I tinned them first and the sweated them together. 
I also shortened them to keep the connection as neat as possible, an 1/8th " overlap.
There shouldn't be any stress on the connection as I wrapped my2 bundles of 7 in duct tape and then wired them together.

John


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## Greg Elmassian (Jan 3, 2008)

Ditto on all the points John made. The contact patches between the tabs should be large enough that it would be very hard to stress fracture the solder joints. 

Regards, Greg


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## izzy0855 (Sep 30, 2008)

Andy, before you solder the tabs together...put a strip of hot glue between each cell, this will releave any stress on the tabs and form a strong bond before you solder. Please do not use duct tape! When your battery-pack charges and gets warm, the duct tape will melt and stretch the heat shrink causing it to rip. If you think you need to strap tape around the pack, use strapping tape (3/4 inch) from your local hardware store. This tape will not melt and has a fiber core to give it more strength. If you have any questions, please feel free to give me a call. 

Rick Isard 
Cordless Renovations 
(319) 366-7294


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## Greg Elmassian (Jan 3, 2008)

I suggest that if your charging system gets the pack warm, the difference between a fabric tape and a HEAT SOFTENING glue is pretty much nil. (I'd actually bet on the tape) 

If you are worried about heat, use ty-raps, not tape or hot melt glue. 

Regards, Greg


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## Bill Swindell (Jan 2, 2008)

The hot melt glue can be used to hold the cells together until the pack is finished. Finish the pack by covering it with heat-shrink tubing.


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## Greg Elmassian (Jan 3, 2008)

Bingo! 

Greg


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## izzy0855 (Sep 30, 2008)

For the beginner...this is an easy and quick way to secure a battery-pack and a Nimh battery never should be charged over 1.5amps...at 1.5amps the hot glue will never melt hot enough to melt the heat shrink around the cells. You shouldn't buy cells with the solder tabs already welded to them, because this is a stress point and a bad current flow and is usually the first place the nickel tabs will lose conductivity and burn. When we manufacture our battery-packs, (Whether it's for DeWalt or the train enthusiasts) we use Hernon Quantum 124 surface sensitive cyanoacrylate glue between each cell that dry's in 15 seconds and is three times the strength of super glue...welded with .375 thick nickel tabs, temperature thermostat, polyswitch, then wrapped with polyolefin tubing. This design gives your battery-pack the proper strength and structure for long-life, durability and performance. More importantly, Andy we would be happy to assist you in any way we can. 

Rick Isard 
Cordless Renovations


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## Totalwrecker (Feb 26, 2009)

If you don't use welded tabs are you suggesting we solder to the batteries? 

While spot welds found on typical batteries might be a problem in a power tool, where vibration and impact are the norm, I don't think packs in our trains encounter anywhere near that stress. If I were that concernd I'd flow some solder around the weld. 

Oh my bats are NiMH, I don't think they get very hot on a trickle charge and are a snug fit in the boiler, no dancing gonna happen in there! 

John


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## TonyWalsham (Jan 2, 2008)

At the risk of contradicting Rick, I would strongly advise those considering building their own battery packs by soldering the cells together, should only ever consider using cells *WITH* tabs already welded to them. After all that is how the manufacturers sell them to consumers. 
DO NOT SOLDER direct to the cell casings.


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## Del Tapparo (Jan 4, 2008)

Posted By Totalwrecker on 29 Oct 2009 03:40 PM 
If I were that concernd I'd flow some solder around the weld. 



And then you defeated the whole purpose of buying a battery with a spot welded tab on it in the first place. You will be applying heat directly to the battery!

Personally, I built a couple of battery packs on my own, and they work electrically, but physically they are a mess. For the couple of bucks I saved and the time it took ... not worth it for me.


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## izzy0855 (Sep 30, 2008)

Oh no, please don't solder to the battery! John, when train enthusiasts purchase tabbed cells through Tenergy or BatterySpace.com they come with thin nickel tabs. (1.125" or less) I would like user's to ask for .375 nickel tabs, their bigger and thicker which will give you more conductivity between cells. And, yes your right...we don't need a HRD (High Rate Discharge) battery like cordless drill battery-packs need, because were not pulling that many amps from our engines. But, I always like to do it right the first time, and I think alot of the time when we're asked a simple question we, "The MLS User's" forget the easiest answer and tend to lean towards, "No do it this way," "But if you do it this way this is going to happen," "Yea, but I have more experience in this matter you should listen to me," and we forget what the question was! The easiest answer is sometimes the best solution. 

Rick Isard 
Cordless Renovations


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## izzy0855 (Sep 30, 2008)

Again, I'm not suggesting you purchase cells with weld tabs on them, but if you do...ask for .375 nickel tabs to be welded to them...and yes, you never want to solder directly to the battery. In doing so you will burn up the electrolytes, they will stop spinning and fall to the bottom of the case, thus shorting the life of your battery-pack. I am suggesting that you purchase a finished product from a manufacturer, this will give you a complete battery-pack with good welds, a thermostat, a polyswitch...welded in the correct order and most importantly...a warranty! 

Andy, I hope through all the static you have come out of this with your answer. 

Rick Isard 
Cordless Renovations


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## Totalwrecker (Feb 26, 2009)

I took what the package deal gave me and knew enough to get tabbed bats, but there was no option for thicker tabs. If and when the tabs fail I'll replace at that time, but I'm not going to dump 2 sets of 14 just because they 'might' fail. 
I'm running two single motored steamers, low draw, the thin tabs should be ok. 

I was wondering how the current builds in a series pack and if the thin tabs would over heat when bumped to over 14 v, then I saw the thin wires between the loco and tender and assumed the low amperage was the reason small cross sections were ok. As far as I know these are or were the same packs car racers use and they are all out all the time.... 

As to the duct tape, it is nylon re-inforced and I don't see any difference than packing tape. What shrink tubing is going to tear? 6 around 1 is a snug package. 

I have soldered to batteries with mixed results years ago and non railroad related... I posed it as a question because of the way it was stated not to get them.... I thought Rick's 'shouldn't get them' needed more talk. Sorry Rick, somehow your super duper glue got in the same thought and that was confusing and the weld of thicker tabs got lost. Do you spot weld them like the others are? Is your spot bigger? I think that matters more than a thicker tab... 


Andy asked how to solder what he had, not what not to get....

John


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## izzy0855 (Sep 30, 2008)

To answer Andy's question; "solder the tabs together with a thin beed of solder cleaned first by lead free paste/flux, make sure the solder penitrates through both ends of the tabs but doesn't touch the cells." To answer John's question; "Thin tabs will work, we do spot weld our battery-packs with six welds per cell, and the welds penetrate the cells by .01 / .02mm." In other words, the only way you can remote the welds is by tearing off the weld tabs then take your Dremel tool and sand off the weld indentations, and even that doesn't fully remove the welds. The reason I suggested the ticker tabs is because the more conductivity you have between cells the better response time the battery will give you. Whether it's charging or discharging your battery, the ticker / wider tabs will supply more current between each cell so your battery can be fully charged & discharged equally. Sometimes thin tabs between the first, second, and third cells when put in series will get hot and burn because your charger is charging at a high current rate (2.5 amps or higher) and the tabs can not handlethe high current rate through to the rest of the cells fast enough. It's like trying to put a medicine ball through a basketball hoop, something has to give...and what gives are the thin tabs. I only suggested the ticker tabs so you get the full capacity and lilfe time out of your battery-pack before the tabs where out. 

Rick Isard 
Cordless Renovations


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## Totalwrecker (Feb 26, 2009)

Rick and all, 
The electronic side of this hobby is my least favorite facet... but if I want to play with the big boys, I need to do as much myself as I can. 
I also needed to understand before I started, I did a lot of homework and nobody ever said; " You shouldn't buy cells with the solder tabs already welded to them," and buy so and so's ... heard the opposite, get tabs! 

The savings I realised was the assemnbly fee, not a lesser battery. granted should I wish to sell them, I'd want something I could garantee, but my true mission is to get the best I can in my budget. Soldering a stable round pack was easy, in fact both half packs match! My real bug a boo is the other wiring, a cold joint and bundled wire that broke the cold joint and made blue smoke. I'm still trying to raise the cash for that repair... 

The All part...I saidl 'If I were _ that_ concerned....' I'm not and I think I have a sound pack, one more on the way, but waiting for a water car nest.... I thought it was ready until the Brass decided fire duty should be part of it's duties... 90% plumbed... 

John


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## abernat (Jan 3, 2008)

Thanks to everyone for replying. I built a pack for my first Bogie and used wires to bind the tabs together. I was hoping for a simpler approach for my second Bogie - and now have it!


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## John J (Dec 29, 2007)

Posted By Greg Elmassian on 28 Oct 2009 10:17 PM 
Bingo! 

Greg Oh crap..All I needed was I 19 for my coverall


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## dms1 (May 27, 2010)

I know I am replying to an old thread, but I wanted to add a few things. Back when I use to race RC cars we always assembled and soldered our own battery packs.


Before doing so we always used clear shrinkwrap sold at the local hobby shop specially made for Sub C Batteries ( I am sure you can find this for other size batteries too) , once you have shrinked the wrap on, use CA instant glue to glue the batteries in the configuration you need, and then solder your tabs on - I recommend using Deans tabs.

Also, if the batteries came with tabs, we would carefully remove themand sand down the ends of the batteries to smooth out the rough spots left by the removed tabs, then use the biggest soldering iron you can find and solder on the Deans tabs. I havent raced RC cars in about 10 years, but I checked with my brother who still races and this is how they still do it.


I plan on reusing my car racing batteries for my Shay and Climax.

FWIW 


http://www.wsdeans.com/products/battkit/index.html

EDIT = I forgot to add that the reason you use the clear shrink wrap is so you wont mess up the manufactures shrink wrap when gluing the batteries together and if you need to take the pack apart for any reason the batteries will look like new with the manufactures wrap still in place.


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## TonyWalsham (Jan 2, 2008)

Dave. 
Advising anyone to solder directly to the cells is totally against what battery manufacturers like Sanyo advise. 
Any sustained heat, like with soldering, on the cell ends will damage the insides and shorten the life span of the cells. 
That is why they spot weld the tags to the cell ends. The heat is instantaneous and dissipates virtually instantly not giving the cells time to heat up. 
Sanyo advice is to only solder to the tags.


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## dms1 (May 27, 2010)

Well I guess the RC car crowd never saw those instructions







. All I know is I tested some of the battery packs i have that were purchased in the 80s and they still seemed to take a charge, it will be interesting to see how these work with the Shay and Climax, although down the line I will replace them with Lithium Ion batteries .


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## Semper Vaporo (Jan 2, 2008)

I think NiCads can handle a quick solder job better than any of the Lithium chemistries... I would not dare try a soldering iron on a Li-xxx battery!


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## Greg Elmassian (Jan 3, 2008)

I've never ruined a cell from soldering it. Would I advise people on this forum to try it? No. 

I think that's been the underlying thought on this thread. 

Regards, Greg


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## TonyWalsham (Jan 2, 2008)

What I don't understand is, why remove the spot welded tabs when they were put there by the manufacturer to assist in soldering together your own packs?


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## Michael Glavin (Jan 2, 2009)

I like Dave and thousands of RC Car enthusiasts have been soldering on the sub-c's for over twenty years.... The secret is getting in and getting out! A hot 80 Watt soldering iron with large chisel tip does the job in a second. There simply is little to no time for the heat to become an issue IMO. If you don’t have the right tools and knowledge it’s probably not a good idea to venture here. FWIW: I’ve recorded cell\pack temperatures coming off the track WELL[/b] above that realized from a quick solder job for a power-bar or lead wire. Some racers even solder there battery into the car on every run!

It's been several years since I've soldered batteries, but the only way you can purchase QUALITY (Sanyo mostly and the like) cells was from battery matchers that load tested and graded thousands and thousands cells; thus grouping/grading like performing cells and offering them individually or as matched sets NO TABS. Yes you could purchase them assembled or with tabs in some cases from some battery matchers/packagers. Typically the cells most desirable were those that maintained the highest voltage under 30 amp loads for four minutes. So you got what you were willing to pay for, cells with less voltage under load or those that fell short of the four minute burn time sold for less...

I can't say I ever hurt any batteries soldering them, as I have always been one to record the actual life and use of said batteries and created spread sheet analysis of mine and other battery assemblies. That said performance RC car/boat/aircraft batteries are subject to extreme abuse compared to our trains needs. Way back when I really got into these sub-c bullies and had my own equipment to load test, cycle and maintain our flock of six\seven cell battery packs. Later in life (starting in 2004) I played real hard with batteries for RC Aircraft flight and power packs. Lithium-Ion had been around for a while Lithium-Poly was just becoming available and we tested, used and abused hundreds of batteries when RC Electric aircraft was in its infancy, today RC Electric Aircraft is HUGE primarily due to the lightweight power afforded us with Lithium Poly and its high discharge potential!!!! 

Michael Glavin


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## TonyWalsham (Jan 2, 2008)

Thank you for a qualified report. 

I would still like to know why one would remove spot welded tabs if they are already installed on the cells. 

I can assure you that unless Sanyo cells are tabbed there will be no manufacturers warranty for self assembled packs. 
I readily admit I do not have the experience of R/C battery flyers & car users. Having been involved with battery R/C for Large Scale trains for 25 years now, mainly using NiCd cells, I can assure you that the majority of Large Scalers would never consider going to such extremes that they do not need to go to. Especially if they have to pay a lot more for what, 10% more performance and a shorter cell life. 
They want batteries cheap and long lasting.


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## dms1 (May 27, 2010)

Posted By TonyWalsham on 17 Jun 2010 10:45 PM 
Thank you for a qualified report. 

I would still like to know why one would remove spot welded tabs if they are already installed on the cells. 

I can assure you that unless Sanyo cells are tabbed there will be no manufacturers warranty for self assembled packs. 
I readily admit I do not have the experience of R/C battery flyers & car users. Having been involved with battery R/C for Large Scale trains for 25 years now, mainly using NiCd cells, I can assure you that the majority of Large Scalers would never consider going to such extremes that they do not need to go to. Especially if they have to pay a lot more for what, 10% more performance and a shorter cell life. 
They want batteries cheap and long lasting. First I want to say I didn't mean to stir up anything here, it is just that everyone in the RC Car hobby soldered their batteries as I did, Saying this:

PLEASE SOLDER BATTERIES WITH CARE AND AT YOUR OWN RISK

Tony, the reason we removed the tabs was because they were held on by four very tiny spot welds that really didnt make a lot of contact, When we used the battery bars (available in the link I posted above) the contact area was much larger and more solid.


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## TonyWalsham (Jan 2, 2008)

Personally I have no axe to grind in this matter. 

My concern is. that less experienced Large Scalers see a posting that says it is OK to solder direct to battery cells. A procedure that the battery manufacturers specifically say not to do, and think it will be OK to pull out the trusty little iron and get at it. 

Thank you for the qualification. 

I can only stress to those considering modifying batteries, the manufacturers consider the cross section of those four spot welds will have adequate conducting capacity for what the batteries were designed to provide. Modifying what the manufacturers have provided will void any warranty.


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## izzy0855 (Sep 30, 2008)

Hello everyone, 

I would just like to add that any temperature over 80 degrees heat applied to any battery, whether that's charging, discharging or soldering heat for an extended amount of time, will cause the battery vents to open thus decreasing it's chance to ever recharge again! Like Tony, I also ask the question why rip out the weld tabs? You will never increase your conductivity between solder joints then what a spot-weld can give. But, you can increase the conductivity between each battery when ordering cells with tabs, if you order through Tenergy call my rep. and his name is Brian x319 and have him weld .375 nickel tabs to each cell end (positive & negative) and make sure you tell him you want the tabs to welded North & South. That means that the postivie end has the tabs pointed to the north and the negative end pointed to the south, it's easier for you the solder between tabs that way. He knows what that means... 

Thanks for listening, 
Rick Isard 
Cordless Renovations, LLC


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## billsharron (Jan 3, 2008)

As I have reported in other threads I have been making my own lithium Ion packs since 2007. I had heard about it from RC guys in Europe and also found some doing it here in the US. I soldered directly to the batteries following the many cautions posted nearly everywhere. I don't really care about the warranty issue since the batteries are so cheap. I use the Tenergy Brand with great success. I use a hot gun and get in and out in three to five seconds. The very first pack I did in 2007 is still going strong running a Bachmann Connie pulling 10 cars on level track for over six hours continuously. 

While it may not be for everyone, if you follow the precautions and understand the issues and feel confident of you skill there is no reason not to do it. Members of my club and others I know have been doing it successfully for 2 1/2 years now. We have never had a single failure. 

I have done several clinics on making packs. I have never had any negative feedback from attendees and I ask them to report any problems. 

While I feel the risk is low that is my own personal opinion and experience. 
Again understand the issues, and do it at your own risk!


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## Torby (Jan 2, 2008)

Some knucklehead busted the tab off one of my NiMH cells. Now who do you think would have done that?


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## izzy0855 (Sep 30, 2008)

Torby, 

Send it to me and well weld a new tab on for you. 

Rick Isard 
Cordless Renovations, LLC


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## Torby (Jan 2, 2008)

Thanks, I'll do that.


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## John J (Dec 29, 2007)

I bought a 60 Watt American Beauty Soldering Iron to make my own Battery pack after reading a aritical in Servo Magazine. I have sort of given up on the idea for a while.


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