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Rebuilding 18 volt batteries for cordless tools.

Started by Dave Shepard, November 07, 2015, 05:16:30 PM

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John Mc

Quote from: Dave Shepard on March 13, 2017, 08:19:03 PM
Quote from: Dave Shepard on March 11, 2017, 07:43:19 PM
...I think I'm going to get the scms later this year, then I'll have three 9.0 batteries. I'll be able to run an entire job site all day without recharging.

Later this year turned out to be today.  :D I didn't get much time to play with the saw, but what I am seeing so far is very impressive.

Have you had a chance to use that Sliding Compound Miter Saw yet? I'm curious if it's still working out for you. My wife does a bit of woodworking. Her miter saw is a garage sale special that we got for $15 (really more of a carpenter's chop saw - and  cheap one at that - than a real woodworking tool). It cuts, but it's not a very rigid frame, so the cuts are not always accurate unless you are very careful.

She would probably use it 95% of the time in the shop. I had been thinking of getting her a decent 12" corded saw, but I see that Home Depot is having a sale on the Milwaukee M18 Fuel SCMS: buy one that comes with a 9.0 AH battery & rapid charger, and get another 9.0 AH battery free. (All our chargers are the standard charger, so the rapid would be nice, as would the extra 9.0 battery.)  I've not really started shopping for the 12" corded version, but this price is less than Milwaukee's 12" corded scms, and about the same as the Dewalt (I don't know if either of them are good saws or not).

So now I'm torn: 10" Cordless, for those few occasions when we'd use it portable, or corded with a 12" blade. She doesn't do a lot of big stuff, but when you need it, it's nice to have.

To the OP: sorry for the topic drift here
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Dave Shepard

I haven't had a chance to really work it for a day, but I'm impressed so far. There are many reviews on YouTube. All have been positive. The big issue is the ten inch capacity. I wanted it mostly to cut dunnage and stickers at the mill where I have no power. Milwaukee days it will cut 400 2x4 of 150 2x12. I've been doing more small woodworking projects lately, meaning not timber framing, and this will make busting out a lot of parts go faster.

The more time I spend on YouTube, the more neat tools I'm finding that Milwaukee offers. Last night I found a combo spot/floodlight that I think I'll get, as well as a ton of other lighting options.

Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

ScottAR

I'm no help on the cordless miter saws but we (dad and I) have two Dewalt sliders and they work great.
They are heavy to move however. I dunno how heavy the other offerings are as ours are older models.
Scott
"There is much that I need to do, even more that I want to do, and even less that I can do."
[Magicman]

Banjo picker

I didn't rebuild my 18 volt batteries today, but I did bring about 5 back to life. I was looking around on the internet for a way to rebuild them and came across this guy that was hitting them with a charge from a small wielder.  I should have just checked the forum here first.  Back in about post 5 Kbietz told how to bring them back, and it works. Here is how I hooked them up.

 

I used my old and I do mean old battery charger.  I set it to the start position which is 50 amps and turned it on for about 10 seconds.  Then I put it on its own regular Dewalt charger and every one of them took a charge.  Before when you put the battery on the charger it would start out blinking like all was well and then in a minute or so you get the really fast blinks that say the battery pack is bad.  After the zap they all charged.  These were all 18 volt Dewalt batteries and you know how much they cost.  By using the battery charger you can get a little distance between you and the battery when you turn on the juice.  I am not saying its not dangerous as I have seen automotive batteries blow up, but it worked for me....your results may vary.  I just wish I could find that old Milwakee hammer drill that I bought that wouldn't charge. Banjo
Never explain, your friends don't need it, and your enemies won't believe you any way.

Don P

Banjo, is that a Lithium Ion or a NiCad battery?

John Mc

Backfeeding a Nicad battery does two things:

  • it may "wake the battery up enough that the charger for that battery will now recognize it and at least make an attempt to charge it up
  • When back feeding, it works better to do a few brief "zaps" rather than one long one: connect for a 2 seconds, disconnect, connect for 2 more second, etc. Do that maybe half a dozen times (or more if you are backfeeding with a lower voltage source). Doing this makes a sort of square wave feedin ginto the battery that can break up internal pathways that have formed and may be creating a partial short, draining the battery.

My electrical engineer friend had me use the above technique and hook up two 12 volt car batteries in series (to make 24 volts) and use that to back feed (connect + to + and - to -) my 18 V nicad tool batteries. It worked on a couple of them. The ones that it did not work on, he had me open up and use a single 12V car battery to back feed each individual cell. Doing individual cells is much more effective than trying to do the whole pack at once, but it's more of a hassle, so worth seeing if you can resurrect the battery without disassembling it first.

He also strongly recommended NOT trying to resurrect Lithium-Ion batteries back feeding them with a higher voltage. He aid you really just want to use their regular charger on them. You might get away with it, but if you don't, lithium-ion sometimes just won't take the abuse, and the results are "not pleasant". (He did admit to knowing a lot more about NiCad than LI-ion, however.)
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Dave Shepard

In the case of the Milwaukee chargers, if they don't see a minimum voltage, they won't charge. If a battery was left in a cold environment for a long time at a low charge, it can drop below that voltage. Normally the battery shuts off before it is too low to recharge, but long term storage or cold can drop it down. If this is the cause of not charging, the solution I've seen on YouTube, use at your own risk  ;), is to hook up a good, fully charged battery for a few minutes to get the dead battery over the threshold voltage. If you have a battery with a bad cell, then this won't work, and you may have a fire. I have one battery that was about 15v, and just needed a couple of volts to bump it up. The others were only 2-3 volts. They are junk. 

After considering the risks, time, and expense of messing with old batteries, I've decided not to bother with them. I've also ended up with so many newer, larger batteries, it became a non issue. 

There are a few more batteries and chargers not pictured. Four M18 chargers,  five Rapid Chargers, and 18 batteries (7-9.0ah) later, I seem to have enough:




Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

John Mc

The Interstate Battery store near me will rebuild NiCad batteries, but they won't touch Lithium-Ion. From what I undertand, their insurance company has a fit about working on LI-ion batteries. They don't know if that is over concerns about some danger in working on them, or the liability if you were the last one to work on a LI-ion battery and it goes up in flames sometime later while in use or storage (same concerns the airlines have about bringing those batteries on board).
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Banjo picker

Quote from: Don P on September 09, 2018, 09:34:52 PM
Banjo, is that a Lithium Ion or a NiCad battery?


They are all NiCads  I checked them this morning and two are extremely low.  They may have a bad cell, but if I have save half of what I started with, I consider it a win.  

Dave with that many batterys and chargers, you may want to seek out a counceling group. :D Banjo
Never explain, your friends don't need it, and your enemies won't believe you any way.

Corley5

Dave I'm impressed you know how many batteries and chargers you have :) 8) :) ;D ;D 
Burnt Gunpowder is the Smell Of Freedom

Ianab

Why you don't mess with Lithium batteries. The lithium is so reactive that it burns in almost anything, including water. If you short one out and it catches fire....

Lithium Metal Experiment FAIL!!! - YouTube
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Ljohnsaw

Quote from: John Mc on September 09, 2018, 10:34:49 PMBackfeeding a Nicad battery does two things: it may "wake the battery up enough that the charger for that battery will now recognize it and at least make an attempt to charge it up When back feeding, it works better to do a few brief "zaps" rather than one long one: connect for a 2 seconds, disconnect, connect for 2 more second, etc. Do that maybe half a dozen times (or more if you are backfeeding with a lower voltage source). Doing this makes a sort of square wave feedin ginto the battery that can break up internal pathways that have formed and may be creating a partial short, draining the battery.


Way back (mid-70's) I was into Remote Control (R/C) airplanes.  NiCad was the best we had and they were expensive.  You had to maintain those batteries year round.  If you didn't, they built up the internal shorts, ruining the battery.  An old R/C magazine had an article about zapping them back to life.  I made one.  Basically a large capacitor bank (about 3,000 mfd) that you would charge up with a 4 or 5 vdc source (IIRC).  You would place a AA battery in the holder that had a VOM attached to it.  You would then press a momentary switch a few times and watch the VOM to see if the battery would hold volts.  The ability of the capacitors to dump a LOT of amps of lower voltage is what did the trick.  It worked quite well!
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Don P

I've also charged up failing battery packs then open them up, disassemble the jumpers from each cell and find the bad ones. I've taken 2 failing packs and made one decent battery. You can also buy those sub C batteries online and refurbish a pack that way.

78NHTFY

Don P--have done the same.  Now have three working Ryobi and two DeWalt 18 volt batteries.  Cost of the generic 18 volt batteries is about $ 13 ea.  A little soldering and it's a lot cheaper than $ 50 plus per new battery.  Youtube is good for stuff like that....All the best, Rob. 
If you have time, you win....

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