Battery Packs

[koehlerrk]

Tore down a couple Craftsman 19.2 battery packs tonight... two that wouldn't hold a charge worth a darn.

Found that one had one completely flat cell, the other had about 7 that showed less than a half volt instead of 1.2.

So, the second pack was obviously trashed, but I took one good cell from it, swapped out the bad cell from the first pack, and lo and behold I have one properly running battery pack again!

Called my dad and he has 3 or 4 of them doing the same thing... looks like I need to visit him and do the same to his old packs.

After this, I'll wind up with one or two empty shells without enough good cells... so then I might try swapping in new cells from Amazon.

Anyone else try this?

[William Yanda]

I had a somewhat similar experience with Makita batteries. I didn't have the technology to resolder so the results were not positive, but the findings were the same.

[RoyEllis]

Being something of a naturally cheap ****, I've been using the $12.99 18v battery packs from "tools by the lb" aka Harbor Freight for donors. Mind you, all my use is DIY around the home type stuff, no long work days depending on them but so far they've done fine.
How are you fastening your jumper tabs between cells?

[jmorris]

This is a subject I will follow as I would like to know more than I do on the subject.

Knowing what the guys do at the local Interstate battery shop that rebuilds my packs do and having sheet metal spot welders, I might be of some kind of help and like to learn more.

They use two "prongs" very close to one another and strips of stainless to join cells together. What current and voltage, I don't know. The duration seems to vary as well but the 3-4 second range seems to hold up (at who knows current/voltage) when I had to take a pack back after an impact knocked a contact loose.

However, I can only say solder is not going to be your friend. Not only does it lack a "solid mechanical connection” that is important for durability it also will likely put too much heat to the cell if you can make a solid connection.

[bangerjim]

If you have gone as far as taking the pack apart and you can get to each individual cell + and - side, you can ZAP each "dead" cell to try to bring it back. 80% will genreally come back.

OK....banger....how do I zap the cells?

I use a variable 8A power supply set at 2V. A cell is 1.2V so 1.5-2v will "pish" the current in. But you need to do EACH cell individually, not in a stack with, say 20V. The shorted ones will not come back and just act as a dead short.

If you do not have a varible PS you can,in a pinch, use a NEW 1.5V "D" alkaline flashlight battery to do a few of them. The current inrush will be high but will taper off rapidly as the cell's shorts burn out. Use you DVM set to 10 DC AMPS to watch the current taper down. I did this a friend's house several years ago and it actually regen'd 5 of the 7 cells that were shorted. They will not last as long as a new battery but will give you some more charge cycles

I have zapped many NiCAD cells like this in my cheeeeeep days, Today I only own LiON battery tools that last for years.

Hope this gives you some ideas! Once you ZAP all the bad cells, put the pack on charge immediately to bring it fully up!

But most packs cannot be soldered as said. The tabs are spot welded and soldering on the cell (if you can even get the metal to "tin" (!) can ruin it from the heat.

I have seen more DeWalt paks in the recycle bin (hundreds) than I care to count. Their cells seem to go south faster than any others. And I have had VERY litle luck zapping the ones I used own (at least 7 tools now in the garbage!).

banger-j

[dtknowles]

I built battery packs for my Electric Powered RC model airplanes. I soldered the tabs to the ends of the cells but you need a heavy duty soldering iron so that you don't over heat the cells (I can go into the technique if someone is interested). I don't recommend reusing cells from a pack that went bad unless you don't mind the short life and multiple rebuilds. When I was building packs I was trying to be cheap so I reused cells for old pack to try and make new pack and I did try shocking cells back to life. Both things do work after a fashion but the life of such salvaged packs is short for a variety of reasons. It kept me entertained back when I had more time than money. I recommend buying new cells and making packs from those cells and recycling the cells from the dead packs. Buying third party packs and disassembling them for the cells could make sense of the packs are a good price but I would wonder about the quality of the cells. I assume we are talking about sub C cells (either NiCads or NiMh)

I have almost completely switched over to Lithium packs and I like them much better, time will tell if they will last longer. My last few years of RC flying I started to switch to Lithium cells and the performance improvement was tremendous.

Tim

[bangerjim]

The replacement cells you buy normally have solderable metal tabs....not a problme.

The cells that are welded and people cut up with tin snimp......not so easy sometimes. Whatever plating they use makes them very hard to "tin" and are almost impossible to solder directly to the cell top or bottom.

Most packs from HF are the cheapest, lowest amp hour cells made by man. Not worth buying or tearing up!

[koehlerrk]

I soldered the tabs back together... no one said I couldn't, so I went ahead and did it. Seems to work just fine, took the battery off the charger this morning, popped it into a drill and it runs like a brand new pack. I have no idea how long it will last, but for the half hour I have in it... I really don't care.

For soldering, yeah, forget the little pencil irons... I have a heavy-duty soldering gun. It's a Weller 140 watt gun and it does the job very quickly... couple seconds is all it takes.

bangerjim, yeah, the cells in the packs have printed on them 1.2v 1300mA - standard sub-c battery cells. I can get a set of 16 2200mA cells to rebuild an entire pack for about $12 less than Sears wants for a new pack. I'm thinking that I'll do that for the second pack I have. And if that works out well, then I can see me rebuilding more in the future.

[alamogunr]

I have seen more DeWalt paks in the recycle bin (hundreds) than I care to count. Their cells seem to go south faster than any others. And I have had VERY litle luck zapping the ones I used own (at least 7 tools now in the garbage!).

banger-j

AMEN! I bought Dewalt cordless tools about 15-20 years ago and did pretty well using them around the house. Batteries finally went dead. The early ones couldn't be disassembled w/o destroying them so I bought another Dewalt drill since it was cheaper than replacement batteries. They didn't last near as long. I guess I could have them rebuilt(I don't want to do it myself) but I'm so down on Dewalt, especially since they were bought out by B&D, I'm thinking about Bosch.

As it stands now, I won't touch Dewalt or Porter Cable, because of the connection to B&D.

[AggieEE]

IIRC some of the battery terminals were nickle plated which makes it very hard to solder. If you have one of the little plater pens, AA battery with a cotton swab on the end. Try putting down a good plating of copper on the term and see if that helps the solderability. Don't dwell too long with the heat as the copper will dissolve off the term.

[pmer]

Couldn't you sand the plating off? Then solder away.

[dtknowles]

Couldn't you sand the plating off? Then solder away.

I grind it off with a dremel tool. Same for the terminals on the batteries. Then I tin the strips and the terminals and finally press the two parts together and apply the iron and remove it quickly. For my model airplane packs I solder the cells end to end to make sticks of cells and join the sticks with straps.

Tim

[xman777]

I do this regularly because I have a Dewalt addiction and buy tons of used dewalt machines off fleabay and craigslist. Pretty much any batteries will work here, don't get too mucked up by brand names. I'll also buy old laptop batteries and grab the good cells out of them. Thats usually 10/15 cells per pack for about a dollar off ebay, and a lot of them come still in the package.

Edit: Don't get hung up on using the plates either, some copper wire works just fine from terminal to terminal.

[snoopy]

Just an fyi, Ridgid cordless tools will honor a lifetime battery warranty if you send the card in, a little pricey but well worth it imho.

[ABluehound]

You can go to a battery warehouse or similar business and get new cells the correct size and even off ebay and put them in. The commercial packs are tack welded together, you can break the tack easily and solder the replacements in. You would be better off rebuilding the entire pack though, the older cells will eventually fail. If you are strapped for cash you might get away with consolidating the good cells from similar used packs too. My secret for my dewalt 18V battery packs is... the only difference between Dewalt battery packs and black and decker is a single tab that can be snipped. That way even when the dewalt packs have fallen on the floor a few times and are beyond repair I can still go to the outlet store and buy a new B&D pack for $30.

[W.R.Buchanan]

This is a subject I will follow as I would like to know more than I do on the subject.

Knowing what the guys do at the local Interstate battery shop that rebuilds my packs do and having sheet metal spot welders, I might be of some kind of help and like to learn more.

They use two "prongs" very close to one another and strips of stainless to join cells together. What current and voltage, I don't know. The duration seems to vary as well but the 3-4 second range seems to hold up (at who knows current/voltage) when I had to take a pack back after an impact knocked a contact loose.

However, I can only say solder is not going to be your friend. Not only does it lack a "solid mechanical connection” that is important for durability it also will likely put too much heat to the cell if you can make a solid connection.

Would it surprise you to know where they get their Econopower Batteries?

Well they are "trade in" batteries that the shop puts new electrolyte in and then onto a grid of batteries wired in parallel that after a couple of weeks restores the battery to it's previous voltage.

If the battery has less than 10 volts it will not take a charge by conventional means however the grid will restore it so that it will take a charge.

I became friends with my local Interstate Battery Shop and the owner was more than willing to show me the process. I buy Econopower batteries for my Dodge Truck which uses two about every 5 years. at $50 a piece it sure beats $250 each for New Group 27 Interstates.

Interstate Batteries are made by Johnson Controls and they were the original Die Hard batteries that Sears sold back when. Then Sears went to Johnson and asked if they could make a cheaper battery and Johnson said no we won't... Sears then went to Exide and they built the garbage that Sears now calls Die Hards. Shame as they had the best but caved to offer a cheaper product that is garbage.

I only buy Interstate Batteries or Optimas for my vehicles.

Randy

[Pinsnscrews]

Sears caved because of all the replacements they installed from idiots destroying the originals. i was working for Sears at the time the change came through. In one month, the shop sold 250 brand new Die Hards, but replaced over 850 under warranty that they knew were destroyed by neglect/misuse/abuse. People refusing to have alternator checks done the. Insisting the alternator was working fine "before that damn 2 mo old Die Hard took a ****". Sears really got crushed by the warranty. When they switched to Exide, they also rewrote the warranty giving them more control of abused neglected batteries.

[koehlerrk]

Well, update for you all...

To date, I've recycled four bad packs into one working pack and one.... that needs more work.

Seems that the second "good" pack has a cell or two that while they show 1.2 volts no-load, when load is applied drop to nothing. So, gotta rig up a load test and do that one again. No big deal... more of a pain really, but lesson learned and figured I'd pass it along here.

Turns out my das still has his old Dewalt cordless drill from when I was a kid. Said he'd love to have it running again, but can't find a new battery anywhere. Told him he should dig it out and I'll order a new batch of cells and build a new pack into that old drill. Always learning... always improving.

[NavyVet1959]

I've never had any good luck with the battery powered tools. As such, I don't buy them anymore. I will stick with ones that you have to either plug into the wall or are air powered.

[bangerjim]

Well, update for you all...

To date, I've recycled four bad packs into one working pack and one.... that needs more work.

Seems that the second "good" pack has a cell or two that while they show 1.2 volts no-load, when load is applied drop to nothing. So, gotta rig up a load test and do that one again. No big deal... more of a pain really, but lesson learned and figured I'd pass it along here.

Turns out my das still has his old Dewalt cordless drill from when I was a kid. Said he'd love to have it running again, but can't find a new battery anywhere. Told him he should dig it out and I'll order a new batch of cells and build a new pack into that old drill. Always learning... always improving.


What your experiencing is a surface charge. The cells in question are defective and will not take a deep charge like they should. That is why you cannot check a NiCad or NiMH cell or back with a volt meter!!!!!! You MUST load it down. I use a 5 ohm 50 watt wire wound resistor. Enough of a load to check the cell. You can use a 12V back-up car bulb for each INDIVIDUAL cell load of you do not have resistors like mine. (6V in you can find them!)

That is just another reason I quite rebuilding battery packs years ago. "Depth of charge" was just too unpredictable.

banger-j