An electrical experiment!

[TopCatGr58]

Hey Folks,

Just wanted to talk a little about cordless drills and their battery packs. I have both an older 7.2 V Ryobi drill/pack, and a B&D 14.4V drill/pack.

The B&D charger died(tested with voltmeter), it merely plugged into the back of the drill to charge the attached battery. Got a larger slide attachment charger requiring removal of battery pack from drill to charge it. Test charged the pack with new charger for 5 minutes, voltage was too high, would not run the drill. I tested the drill with separate 12 volt battery, worked fine! Took battery pack apart, found exploded corroded cell amongst the 12 cells in the pack. It takes the 4/5 Sub-C style Ni-Cd battery. This bad pack/cell is probably what burned out the OEM charger.

The Ryobi 7.2 V pack has 6 Full Sub-C Ni-Cd batteries, they are just OLD and worn out, will hold "some" charge, but not very much or very strong. So I've decided to replace/rebuild both packs.

I know that HEAT is the Ni-Cd battery's enemy and that I can't simply solder tabs to the batteries to be able to link them up! However, I have been able to find both styles of batteries with built in solder tabs, so I can use my low heat Cold/Heat battery powered soldering device to quickly solder the tabs together while not sending/putting much heat into the actual battery itself.

Due to the old style of battery charger, I decided to stay with Ni-Cd batteries instead of Ni-Mh, plus with this application...DRILLs, the Ni-Cd's can discharge/provide their power quicker and more completely than the Ni-Mh and I won't have to worry about compatibility of the old chargers.

The batteries are coming from Hong Kong via Ebay, the 12 set for ~$18.00, the 6 set for ~$10.00..free shipping for both. I've taken photos, marked the (+) and (-) ends of each cell to be able to replicate it precisely in the new pack arrangement.

I'll be letting folks know how it turns out, works, etc., just curious if others have attempted to do this? I don't have one of those fancy battery welders that professional pack rebuilders use for this purpose, but am hoping that with using the pre-tabbed style batteries, I'll be able to link them without heat damaging the batteries, and have new battery packs for easily 1/2 or less expense than buying new packs or Professional rebuild.

T.C.

[jwhughes3]

Youll be fine

Try adding some hemostats to tabs as heat sink while soldering.

I did this with salvaged cells with mixed success but didnt have the cold soldering device. Hope your experiment goes better.

John

[b.walker5]

Just done this a couple of weeks ago with a 12v Metabo pack. Worked fine. Be quick withe soldering iron and you wont have any issues. Just check that the milliamp/hour ratings match what your replacing if you want the same power output.

[natemoen]

Should work just fine.

[TopCatGr58]

Thanks,

The cold/heat soldering device is a misnomer of sorts, the soldering is still using heat, but the soldering tip is graphite or such , so it doesn't retain heat and so the tip is cold after you use it, but it still generates heat between the split electrodes for soldering.

SO...I was thinking of possibly putting the pack in the freezer for a while after assembling and ligning up the tabs prior to actually doing the soldering. I wouldn't FREEZE the pack, but just get it down to ~40 degrees or so, similar to what it might experience if left outside. The tabs are quite thin, so I expect to be able to perform the application of solder between them quickly with very little heat transmitted to the actual battery proper.

I don't have any information about the mah ratings of the older batteries, but I've heard that most of the time they are fairly low, ie. 1000mh or such because they are cheaper, and cheaper brands will use this to save $$.

The 12 pack will be using/getting 1600 mah units, the 6 pack will get 2500 mah since they are larger/longer in size, they have more space to store more capacity...or at least that's my theory, and it makes sense that the lower volt unit would need more power to be able to keep working, and Ryobi isn't a cheap brand like B&D is!

It'll take 10-14 days to receive the batteries, so it'll be a little while before I can post an end result. I'll take photos and such, perhaps even make a MISC tech tip for us!

T.C.

[81xsproject]

One thing I have seen others do is to get BETTER batteries, ie ones with higher amps for longer running time for your tools.

[xs11jack]

There is a soldering aid that is a paste. It works as a heat dam. So if you put some on top and bottom of the tab, it will keep heat from damaging the cell. As for your soldering iron, is it one of those 'as seen on TV' things advertised a few years ago? If so I would get a pencil type soldering iron of about 25 watts, or a 35 to 50 watts with a medium sized tip. I might even put a small dab of soldering flux on both surfaces just before soldering.
Ole Jack

[CatatonicBug]

I got tired of batteries dying and bought a Ridgid. Lifetime warranty on the batteries. Already had them replaced once, about 2 years after I bought it. The lithium batteries make the whole thing much lighter too.

[DCracer25]

I would like to know how you make out I have a 24 volt impact gun that the batteries keep dieing after about 6months of use. and where you got the batteries from.

[natemoen]

I would like to know how you make out I have a 24 volt impact gun that the batteries keep dieing after about 6months of use. and where you got the batteries from.

I have had Batteries + rebuild battery packs before for way less than what it costs to buy a new pack.

[TopCatGr58]

I would like to know how you make out I have a 24 volt impact gun that the batteries keep dieing after about 6months of use. and where you got the batteries from.

Hey DC,

I've done a bit of reading about the difference between Nicad and NiMh batteries that surprised me. The Old school idea that Nicads should be run completely dead before charging, or to run the device to totally drain them is a bad technique. The devices like Drills, etc. which use high flow rates and quick discharges will NOT develop memory problems. Internal damage occurs to the battery cell structure if allowed to fully discharge. Also damage can be done if charged too long also...left on a charger if it's NOT a smart charger. Keeping them away from HEAT is also important, so storing in a car/truck in the summer sun is also not good. They should be recharged once a month if not used often. I wish I had saved the web page link I found that provided the indepth structure/function of Nicad batteries.

You may want to check your charger for proper function, and if it's a smart one, or just a timed one..it could be damaging the battery pack!?

I'll definitely keep everyone posted on my results and progress!
T.C.

[fredintoon]

Hey Folks,
Just wanted to talk a little about cordless drills and their battery packs. I have both an older 7.2 V Ryobi drill/pack, and a B&D 14.4V drill/pack. - - -

Hi T.C.,
good luck with your battery pack refurbishment program.
What I'd like to whine about is the several different Voltages and plug-in shapes that battery packs come in.
I went through the same nonsense in the UK with domestic power plug-ins. OK, it's sorted these days but back in the 1960s there were at least 5 different styles of power outlets, sometimes they were in the same house!
These days the power pack in my 12V Black & Decker drill will not interchange with the pack in my 12V Mastercraft drill
and WTF can they not pick ONE voltage rather than a whole slew of them?

[motoman]

Interesting read. Can see this area happens to be a few folks forte, but not mine. I'll just have to put up with my 1/2"chuck, wrist twisting 18.5V Milwawkee..............

[cywelchjr]

Fred, it's all about cost and power. The higher voltage tools have more power, but both the tool and the batteries cost more, sometimes significantly more. Then you get into the thing that most are still NiCad, but some use NiMH and some of the high tech ones are using LiFE batteries, all at different price points and power storage capacities. Then there are the ones with a cord, which don't ever run down or need the batteries replaced, but need a plug to plug them in to.

[natemoen]

Each brand wants you to have to buy their battery when you need a new one, if they all interchange then everyone would buy the cheap chines batteries at half the cost of the name brand batteries.