I researched the rebuild cost for my Craftsman 19.2v battery packs. I could buy two new ones for $10 more than the rebuild cost of one! That was with the battery shop doing the rebuild.

I rebuilt a craftsman with 11 niCad batteries(13.4V) into a 12 NiMH battery(15.6V) with 2/3 more capacity for about $10 less than buying a new pack from Sears.

Actually I think it's 2 - 3X more capacity...

 

I rebuilt a craftsman with 11 niCad batteries(13.4V) into a 12 NiMH battery(15.6V) with 2/3 more capacity for about $10 less than buying a new pack from Sears.

The difference must have been the labor cost, in my instance.

 

The kind of batteries we are talking about here is for most of you regulated in "HOUSEHOLD AND COMMERCIAL BATTERIES - UL 2054" The socope of UL 2054 is

1 Scope
1.1 These requirements cover portable primary (nonrechargeable) and secondary (rechargeable) batteries for use as power sources in products. These batteries consist of either a single electrochemical cell or two or more cells connected in series, parallel, or both, that convert chemical energy into electrical energy by chemical reaction.​

These requirements are intended to reduce the risk of fire or explosion when batteries are used in a product. The proper use of these batteries in a particular application is dependent on their use in a complete product that complies with the requirements applicable to such a product
So to some interesting parts​

4.1 Casing and Enclosure
Revised 4.1 effective November 11, 2011
4.1.1 The casing of a cell or single cell battery, or the enclosure of a battery pack shall have the strength and rigidity required to resist the possible abuses, that it is exposed to during its intended use, in order to reduce the risk of fire or injury to persons.
Revised 4.1.1 effective November 11, 2011
4.1.2 The casing of a cell, or single cell battery, or the enclosure of a battery pack shall be rigid enough to prevent flexing that would result in damage to the cells or internal protective components. A tool providing the mechanical advantage of a pliers, hacksaw, or similar tool, shall be the minimum mechanical capability required to open the cell casing or battery pack enclosure.
4.1.3 For battery packs with plastic outer enclosures, the outer enclosure of the battery shall be designed such that it is not capable of being opened using simple tools, such as a screwdriver. The enclosure shall be ultrasonically welded, or secured by equivalent means. Adhesives complying with the adhesive requirements of the Standard for Polymeric Materials – Use in Electrical Equipment Evaluations, UL 746C,
single use or tamper-proof screws are considered equivalent means.​

Revised 4.1.3 effective November 11, 2011

I can not list all tests. But I will quote the short circuits test.​

9.8 Each fully charged test sample battery pack, in turn, is to be short-circuited by connecting the positive and negative terminals of the battery with a circuit load having a resistance load of 80 ±20 m ohm. The temperature of the battery case is to be recorded during the test. The battery is to discharge until a fire or explosion is obtained, or until it is completely discharged and/or the cell case temperature has returned to ±10°C (±18°F) of ambient temperature.​

Revised 9.8 effective November 11, 2011

9.11 One of the above five test sample battery packs, tested at 20 ±5°C (68 ±9°F) shall be evaluated with the following additional conditions in place. The terminals are to be subjected to a short circuit condition with a minimum length of 16 AWG (1.3 mm2) bare copper wire. The test is to be conducted on a tissue paper covered soft wood surface and the sample battery pack and bare conductor is to be covered with
a single layer of cheesecloth.
9.12 For all samples tested, the samples shall not explode or catch fire and the tests shall not result in chemical leaks caused by cracking, rupturing or bursting of the cell casing. The temperature of the internal cell casings shall not exceed 150°C (302°F). For battery pack samples tested in accordance with 9.11, the cheesecloth and tissue paper shall not catch fire.​

Revised 9.12 effective November 11, 2011

Modern Cells pack a lot of energy. And I find it hard to belive that battery pack for cordless drills do not have any protective measures like some kind of fuse. Probably both current and thermal.

 

All the packs I have taken apart have thermal fuses and current fuses.

 

Hopefully I covered all the questions.

You haven't told us the make and model of your drill.

Sorry, WORX WA3152 18-Volt NiCd

If you're looking at spending $30 plus shipping alone for the cells and you're still saving $50, I assume you have a DeWalt, Makita, or similar.

Sorry, must have been thinking of a few things when I wrote this. I had a local battery shop fix mine back in April for ~$50. At the time too, I found the factory ones on Amazon for ~$60. I see they now sell them for closer to $45.

I am not buying a stock pack though. I have 3 packs total and this is the 2nd that's crapped in 2 years and comparing the stock to the rebuilt is night and day

If they don't have a thermal fuse or the like, I'd be a little concerned.

No, sorry. I have not see anything other than the batteries & tabs in the pack. I just did a search though and it's possible they do. I found some pictures showing the fuse is built-into one of the tabs, which is not what I had in mind, so maybe...

Alternately, Home Depot sells a two-pack of 18V Ni-Cd batteries for $60. Those would include a thermal fuse and soldered tabs. You may need to move a couple of cells around to make it fit your battery case, but you'd save on shipping and assembly time.

This is not a bad idea. It looks similar in shape, but like you said it could require minimal moving. This still wouldn't eliminate the need to solder/weld at least a few terminals which seems to be biggest issue most here have.

Make sure they are all the same or there will be problems.

Personally I would not try this except with tagged cells, of a type which are intended for soldering into circuit.

I've done the solder method a couple of times successful. But would highly recommend the tabbed batteries.

Yes, as noted in a few previous posts, I intend to get all identical cells specifically designed for use in making battery packs. They already come with tabs, but I'd still need to attach those tabs to the adjacent battery. The batteries I posted a link to had tabs on both terminals, so these could be as simple as attaching the tabs together.

I researched the rebuild cost for my Craftsman 19.2v battery packs. I could buy two new ones for $10 more than the rebuild cost of one! That was with the battery shop doing the rebuild.

This may be true, but making one with a much higher mAh rating that alone lasts twice as long and maintains it's power is worth the extra value. My guess is the stock/purchased ones have a much lower rating.

I have also not heard good things about factory/stock battery packs in general and would rather not take the risk. My drill is not a dewalt or similar, so it's more likely I could get a dud. I have 3 packs for my drill and this is the 2nd that went bad in less than 2 years. The third is holding strong so seems very apparent to me the problem is shitty quality packs. If any one of the batteries is bad, it can instantly ruin the entire pack.


The biggest question I have is:

Obviously SOMEONE connects the batteries together with each other in a battery pack. I'm pretty experienced with soldering and/or could have access to a welder. Is the concern for my safety and that I should let someone else rebuild it and possibly hurt themselves instead? Is the problem is that soldering/welding to batteries is not the recommended method? If so, how are the current battery packs made, do they use some kind of thermal glue, like a JB Weld instead? I'm 100% open to knowing the proper way to connect batteries.

When taking it to a battery shop to rebuild it, someone there is doing the work. Yes, they have been doing it for a while, but it's still someone. I may not be experienced in making cordless drill battery packs, but this seems far within the realm of experience I have with other electronics projects. In fact, all things considered, connecting a few batteries is much easier than other simple projects I've done like a batter powered USB charger.

I'm a DIYer. If doing something costs me more than not, chances are I'll still do it. The extra $ I spend is for the fun and experience of doing it. This is supposed to be a projects forum, yet it seems every time I post project questions here they are consistently shot down rather than giving helpful advice or even constructive criticism. I love all the info this site offers, but maybe I'm just still too much of a beginner that my questions should be self apparent, but I am gradually not enjoying my experiences here.

 

The difference must have been the labor cost, in my instance.

Perhaps. You would not want to have paid their labor cost/hr. for my time invested, it probably would have run you $200.00!

They obviously have the experience and tools to do it more efficiently and they get their batteries for less too.

 

The biggest question I have is:

Obviously SOMEONE connects the batteries together with each other in a battery pack. I'm pretty experienced with soldering and/or could have access to a welder. Is the concern for my safety and that I should let someone else rebuild it and possibly hurt themselves instead? Is the problem is that soldering/welding to batteries is not the recommended method? If so, how are the current battery packs made, do they use some kind of thermal glue, like a JB Weld instead? I'm 100% open to knowing the proper way to connect batteries.

When taking it to a battery shop to rebuild it, someone there is doing the work. Yes, they have been doing it for a while, but it's still someone. I may not be experienced in making cordless drill battery packs, but this seems far within the realm of experience I have with other electronics projects. In fact, all things considered, connecting a few batteries is much easier than other simple projects I've done like a batter powered USB charger.

I'm a DIYer. If doing something costs me more than not, chances are I'll still do it. The extra $ I spend is for the fun and experience of doing it. This is supposed to be a projects forum, yet it seems every time I post project questions here they are consistently shot down rather than giving helpful advice or even constructive criticism. I love all the info this site offers, but maybe I'm just still too much of a beginner that my questions should be self apparent, but I am gradually not enjoying my experiences here.

No, It's not that that they are being shot down, but rather within the realm of experience of the guru's on the site they can sometimes only offer best guesses as to how some things are done. And when it comes to a task that could possibly be dangerous to the OP (You in this case) they would rather error on the safe side. This is why some recommend the safer route of approaching the task. If you have or can find the information needed to perform the task safely, then by all means do it. If you ARE a DIY'er then the real task at hand is to talk to the appropriate people with the experience via personal conversation, phone communication, email, and even forums such as this one, and then get the equipment necessary to perform the new skill you desire to learn. If I told you that those that do rebuilding of battery packs wear full face shields, protective clothing, and are behind a protective barrier, and that they have the appropriate fire extinguisher training, not to mention the specific hand tools for the rebuild, would you go out and invest the $$ to do it right and safe?

 

The mAh rating isn't critical to operation. The battery charger will charge it just the same. If you get a lower mAh rating than what you had, you'll have less runtime, more if you get a higher rating. You just want to make sure you get the right chemistry - I assume you have a Ni-Cd or Ni-MH, not a Lithium - so the charger works properly with the battery pack.

The part in bold above is ONLY true when building a completely new battery pack.

What often "kills" battery packs is a single cell that started out with less capacity than the others. Since they are run in series, that weak cell would run dead first. When the cell count is high, there is still enough voltage to operate the device, so the current still flows through the dead battery, but in reverse, so the pack charges the battery backwards during discharge.

Next, that weak cell isn't just a short/bad battery, but is actively working against the other cells, causing the next weakest in line to fail the same way. When this happens in Lithium batteries (non-rechargeable and rechargeable), the result is fire. ref: Most notebooks in the mid 2000's, Dell being the highest profile case, and Surefire ultra-bright CR123 batteries from China in the non-rechargeable case.

The same failure mode will happen if you put a 1500mAH battery into a string of NiCd/NiMH rated for 2000mAH, the result will be a destroyed pack if discharged below 1V/cell, or roughly when it barely starts showing signs of running dead. If run until the tool won't operate any longer, the "repaired" pack will be ruined again in as little as 2 charge/discharge cycles. So be sure to match your mAH rating as close as possible when replacing one cell in a string, or when building a new pack.

 

The radio control guys build battery packs all the time. Google for them and their message boards. There are some tricks for soldering without overheating the cells, or for spot welding them.

 

Also one thing. The battery charger delivered with your drill is made for the batteries in the original pack. If the batteries you are using as replacement. are very different. You may get a poor charging of your new batteries. And hence wear them out quite fast

 

He plans on an upscaleing his capacity, or so i thought i read. Higher mAH battery won't give the charger any problems, just take longer to charge and this is good for the battery.

Safety can't be under stated here. Nothing conductive you don't have to have near by, cover the connections immediately, ect. For abit of anecdote I once shorted a small 1/2A pack with a pocket knife replacing it's shrink wrap, 1/2A supply only 1-200A or something silly D cells MUCH BIGGER than 1/2A.

I'd suggest dual tabbed matched cells, maybe from an RC battery shop. Dual tabs can be soldered twisted/rolled or resistance welded. So you could go purely mechanical attachments, with dual tabbed.

They use a special treatment for attaching to aluminium with solder. I think someone mentioned it above, it eats off the oxide so you are not trying to attach to "glass". Basically flux with an really high acid content if my memory serves.

In theory you could weld the tabs on with another assembled pack but that smacks of "giving a monkey a machine gun", there are safer alternatives.

DIY Battery tab welder
http://www.rcgroups.com/forums/showthread.php?t=763308

uses this guys circuit, a must read.
http://www.philpem.me.uk/elec/welder/

Scroll past the circuits, they are pure theory aka DANGER.
But the actual welding info and pictures, shows some good and bad welds.
http://www.hobbyspotwelders.com/basics.php
Controllable and repeatable pressure, adjustable current, and electrode sizes are important.

 

He plans on an upscaleing his capacity, or so i thought i read. Higher mAH battery won't give the charger any problems, just take longer to charge and this is good for the battery.

Safety can't be under stated here. Nothing conductive you don't have to have near by, cover the connections immediately, ect. For abit of anecdote I once shorted a small 1/2A pack with a pocket knife replacing it's shrink wrap, 1/2A supply only 1-200A or something silly D cells MUCH BIGGER than 1/2A.

I'd suggest dual tabbed matched cells, maybe from an RC battery shop. Dual tabs can be soldered twisted/rolled or resistance welded. So you could go purely mechanical attachments, with dual tabbed.

They use a special treatment for attaching to aluminium with solder. I think someone mentioned it above, it eats off the oxide so you are not trying to attach to "glass". Basically flux with an really high acid content if my memory serves.

In theory you could weld the tabs on with another assembled pack but that smacks of "giving a monkey a machine gun", there are safer alternatives.

DIY Battery tab welder
http://www.rcgroups.com/forums/showthread.php?t=763308

uses this guys circuit, a must read.
http://www.philpem.me.uk/elec/welder/

Scroll past the circuits, they are pure theory aka DANGER.
But the actual welding info and pictures, shows some good and bad welds.
http://www.hobbyspotwelders.com/basics.php
Controllable and repeatable pressure, adjustable current, and electrode sizes are important.

Almost all the tabbed batteries I'm finding are dual tabbed. I was thinking with this setup, as you said, I could just mechanically attach them together and eliminate any soldering at all.

I am extremely safety oriented...well, as much as anyone tries to be when they are conscious of it. I'm a 2nd year EE student (associates), so safety has been bore into me for some time now. I've asked a few of my profs, but nobody really has much experience with batteries. I'm also working on wanting to build another battery pack for a different application and thought this would be a good leeway into it.

 

No, It's not that that they are being shot down, but rather within the realm of experience of the guru's on the site they can sometimes only offer best guesses as to how some things are done. And when it comes to a task that could possibly be dangerous to the OP (You in this case) they would rather error on the safe side. This is why some recommend the safer route of approaching the task. If you have or can find the information needed to perform the task safely, then by all means do it. If you ARE a DIY'er then the real task at hand is to talk to the appropriate people with the experience via personal conversation, phone communication, email, and even forums such as this one, and then get the equipment necessary to perform the new skill you desire to learn. If I told you that those that do rebuilding of battery packs wear full face shields, protective clothing, and are behind a protective barrier, and that they have the appropriate fire extinguisher training, not to mention the specific hand tools for the rebuild, would you go out and invest the $$ to do it right and safe?

Well, no...I probably wouldn't. But based on the project itself I didn't see that as an option. Given a local battery shop could rebuild it for ~ the same price and with a higher mAh battery, I figured I could give it a run for, if nothing else, the same price. At best, for a significant amount less. I'm also despiritely in need of learning to make my own battery packs for future projects and thought this would be a good stepping stone. Regardless if this turns out, I'll be researching batteries until I'm able to accomplish what I'm looking to do.

I definitely can relate to your (or any of the guru's) desire to see everyone safe. I for one would not want to make any suggestions here only to find out it caused harm to another reading it But I also feel this sense of...idk, maybe I always ask questions about projects that do take a higher level of skill than I'm capable of i.e. I'm an experienced hunter. I know how dangerous guns can be and how to safely handle them even in situations that look like I am not. But I don't tell people looking to hunt that guns are dangerous and should't use them

Going into electronics, at some point I'm gonna have to get my hands dirty. Believe me, as safe as you want me to be, I value my safety even more! hehe Thanks for understanding.

 

I re-cell'd one of my 3.0Ah NiMH Panasonic battery packs with higher capacity 3.8Ah tabbed Sub-C cells for all the same reasons you stated. Bought batteries from All-Battery.com (they also have an eBay store so it's best to check both places for the best deal).

I cut a mylar wedge and slipped it between the cells and their tabs before soldering. This keeps the heat from melting the cell's plastic covering (unfortunately, I didn't take a pic with the mylar insulator).

creakndale

 

I bought a 18 v drill battery from harbor freight for 15 dollars. Open it up and get tabbed cells ( sub c? ) Cut apart the ones that are not wired the way I want, and get the excess as tabbed cells ( for re wiring ) for a price that cannot be beat.

 

I bought a 18 v drill battery from harbor freight for 15 dollars. Open it up and get tabbed cells ( sub c? ) Cut apart the ones that are not wired the way I want, and get the excess as tabbed cells ( for re wiring ) for a price that cannot be beat.

But I bet they were NiCad and offered a dinky capacity rating like 1300mAH...