Dead Milwaukee Battery, might not be so dead afterall…

Posted by Dan on Dec 3, 2009 @ 4:05 PM

Several years ago, I bought a set of Milwaukee power tools. I love the tools, but one of the batteries seemed to die after a few years (but very little usage.) The batteries are like $80 and since I don't use the tools very often, I've never bothered replacing the one that seemed to be dead (since I have 2 batteries.)

However, today I came across a very cool tip.

Apparently these "dead" batteries are a known issue with Milwaukee and often the batteries aren't dead, but just need to be jump started. To awaken one of these dead batteries, place a standard 9-volt battery against the leads on your dead Milwuakee battery for 30 seconds (single lead on your Milwaukee is positive, the double lead is negative.)

Sure enough after doing this little tip, I was able to plug my battery in to the charger and it started charging it!

Categories: Potpourri


  • i have a lith ion 18v, when its charging the battery flashes red, while the charger is a constant red, it even turns green saying its fully charged. Im wondering if this is my issue since i didnt use the batteries in like 3 weeks. let me know what you think. Thanks a lot
  • @Cam:

    You can try it, it won't hurt anything. In my case the light just stayed a constant red, but it would never charge. I don't use the batteries a lot, so this happened after not using the battery in a few months (and then because I thought it was dead, I went a couple of years before trying this tip.)

    Doing this shouldn't harm the battery at all--there's not enough juice coming out to hurt the battery, but it appears there's enough to reset the battery's memory.
  • Wow- thank you for this. Both of my Milwaukee 18v batteries where dead. (I thought)
    They are both charged and running great. You just saved me at least $100.
    Thanks again-
  • it worked!!!
  • That is awesome! My battery is working again.
  • We lol this work on the V28 battery?
  • My Lithium-ion 18v batteries (2) have five slots that fit into the charger.
    I have the same propblem that Cam has with the charger showing red then
    green but no power in the batteries. Which slots do I use to jump with the
    9 volt?
  • Hi,

    I'm having the same problem with two identical batteries that came with my Milwaukee drill. They're 18-volt batteries and I'm examining them in hopes of performing this trick you're recommending. However, would it be possible for you to post a photo of your battery? Mine has no exposed metal "leads," or anything that would resemble something to which you could simply hold a 9-volt battery. My battery connects to the charger by sliding into a series of 5 plastic grooves. Any metal contact points are within the battery itself.
  • I had the same problem with two "Red lithium" 18v batteries: charger pretends to charge, turns green after a while indicating a full charge but batteries are still dead. The solution? New charger from Amazon for less than 30 bucks. Both batteries work flawlessly and I'm glad I don't have to go through the pain of warranty replacement, yet.
  • Hi
    same story with the battery and the five grooves.
    Just where do you place the 9 volt battery?
    Anyone there
  • Both my 3.0Ah batteries seemed to have packed in around the same time. I was using them outdoors in very cold damp weather. The charger was flashing between red and green which indicates broken battery. So I took them home and forgot about them for a fortnight or so then thought I would give them another try. They are not that old or used and both have now charged up fine. Anyone else had a similar problem with cold damp weather ?
  • Rubbish, no leads on Milwaukee batteries, they slot into the charger this is not possible
  • This will help you identify the leads on your 5-connector battery:

    It is basically the outer two slots. The one with the white sleeve on it is the ground. You can look at the video to understand the proper orientation. Or you can just unscrew the top and identify it by its sleeve.

    I plan to try it on mine, once I dig up a 9V battery. But I have no specific knowldge on whether this will work.
  • Hopefully some of you are still following this thread and can maybe help a guy out here: I've had a Milwaukee cordless drill for about 3 years. I use it daily. It stopped working properly, so I purchased a refurbished one (similar to my first one). The batteries from my first one still work fine, but when I have them fully charged and put them on my new gun, nothing happens. BUT! (this is where I get lost...) If I put the batteries on the old gun and pull the trigger one time (this causes the LED light to come on on the old gun, but nothing else happens) and immediately put the battery on the new gun, it will work perfectly fine AS LONG AS I don't let the gun sit without being used for more than 3-5 minutes. My batteries work perfectly on a Milwaukee drill that my friend brought to the shop, so I don't believe it is a battery issue. Any help with what may be wrong with my refurbished gun? Thanks in advance!
  • Just got a brand new M18 3/8 one key impact driver... one battery started blinking green and red as soon as I put it in charger.... and it's BRAND NEW!
     Tried to call Milwaukee... busy, ( it's Friday night so, I figure I'll try on Monday.
    The more I thought about it, the more it bugged me... googled dead M18 battery, found this blog, and thought, why not?.... came into work, found a brand new 9 volt battery, jumped it to my 5ah M18...( let it go to about 7 volts)... snapped it in the charger and WA-LA!!!!..... works fine, charged fine!!
    Thanks VERY much, saved me the hassle of trying to return and deal with that!!
  • I just tried this on my m18 red lithium battery. It works, I did a bunch of google image search to find which leads are (+) and which were (-). I used a 12v psu and charged it for 40sec and then put it back on the charger. Next morning it showed all greed (4 bars) on the battery itself. Thank you!
  • Hate to say this but it worked, at first my 18 lithium battery did not work so I tried it again and left my 9 volt attached for a little longer then 30 seconds when I heard a sound like a pop so I disconnected it from the 9 volt and placed on my charger and to my surprise it worked I was happy as hell
  • Just tried it on my 18v and I will say after about 15seconds I heard the battery click. Held the 9 volt connected to it just a little longer and YES it does work.
  • Christopher Wilk's Gravatar
    Christopher Wilk
    Works like a charm! If you can follow these bloody easy directions, to figure out where the leads on the battery are, you bloody well shouldn't be using an 18v Milwaukee drill gun mate!
  • Yep, worked straight away - all good.
  • I pushed a new 9 Volt battery into dead Milwaukee battery as described above then placed it in the charger... and it worked!!!!...Thank you for the great tip!!!
  • Wow, I'm a bit amazed and a lot relieved. Bought a Milwaukee 18V drill at HD last year on sale for $100 when my ancient (8+ years) Ridgid drill finally stopped working at all (batteries both dead, bearings and gears getting kinda shot) and the Milwaukee worked well enough. But for the past few months the charge it holds has dropped steadily. I charge maybe 2 or 3 times per week, about half the time when I've run it down to zero, the other half when it's just showing 1 LED when the button is pressed.

    Yesterday it stopped utterly. Putting the battery into the charger resulted in about 3 seconds of red, then glowing green as though fully charged. Weird, as it had been able to run for about 2 minutes before that, the battery obviously not totally dead. I tried pressing and holding the button for a lot of seconds on impulse, and presto, the LEDs went through some sort of 'diagnostic' series of blinks... but nothing changed, still wouldn't charge, still told me it was fully charged when plugged in while flashing 1 LED with a single button push.

    So this morning I searched... and found this great thread. Tried it with a nearly dead 9V battery (showing under 8V with a multi-meter before trying this) and held a couple of pieces of 1/8" aluminum wire with the ends squashed flat to squeeze into the outer two battery slots. Wore safety goggles, held battery with pliers, kept fire extinguisher at hand... but nothing bad happened. Didn't look like anything happened. Certainly no *POP* sound as one user reported here. I left it connected for about 1 minute. Checking the 9V it was slightly warm. Okay, so something happened. Put the Milwaukee M18 battery into its charger, and WOW, it lit up RED! Stayed that way for about 10 minutes, then went to green. Testing in the drill it works now, which is amazing, as I have a bunch of work to get done today and some of it requires a hand drill.

    So it seems the battery needs a jump start eventually. If it dies again I'll try again. Oh yeah, and the 9V meters at 0 volts now. Just the slightest jump of the needle when connecting. So it plainly dumped whatever it had into the drill battery.
  • Too good to be true as it turns out. I should have waited a day or two before gleefully reporting success. While the jump-start with the 9V battery did give the battery the ability to take a charge, after a few uses totalling around 2 minutes of drill time it died again and now refuses to take a charge. I'll have to go get some cheap 9V batteries and see if this is to be a regular thing until I feel like coughing up $100 plus tax for a new battery.
  • Worked for me too! I just paralled a fully charged v18 L-Ion battery with my v28 L-Ion battery that wouldn't charge (Charger flashing Red-Green). I let it "cook" for about 15 minutes, put the v28 on the charger and viola! Solid red LED on charger and first red battery LED charge indicator is lit.
    OK. I'll share a Ni-Cad trick with you guys. If you have one that wont charge or only partly charges, do the same as above, but double the voltage. For example, put (2) 18 volt batteries in series to restore one 18v battery. just connect it for only about 10 to 15 seconds. What this does is it burns off the sulfates that are shorting the battery out internally. This works most of the time. Repeat if it doesn't.
  • Hi
    Just want to know would this trick work with any lipo batteries as I have a few dead RC drone batteries that are dead.
  • Thanks!!!!!
  • Yes it works great had a "RED LITHIUM" M18 5.0 that was left on my impact and not charged for about 5month. Placed the battery on my charger and received a flashing red-green-red-green. Indicating a damaged battery. Jumped the power and ground with a 9v. placed the 5.0 on the charger and it showed the charging light and the battery changed completely
  • Will try.
  • I tried. I got the green light on the charger but the battery continues dead. Huh?!?!?! I will let it sit and see what happpens. Then I will try the 9volt thing again.
  • Have two of the 48-11-1828 XC one works fine, the other will not work in my tools. Well it will if I only charge it 3/4 to just when the forth LED on the battery turns on. If charged longer the green light on the charger will not come on indicating a full charge and the battery will not work in the tools. I first ran onto this over two years ago and just let the battery sit. The LED lights on the battery would come on by themselves and stay on for maybe a day or two... weird. After sitting for over two years I grabbed the battery and put it on the charger. I could hear the charger cycle , tick..tick..tick and the first LED on the battery would blink in time with the ticking from the charger. After about three minutes the first LED stop flashing and stayed on all the time. I knew the battery was taking a charge. after the second LED on the battery came on I pulled the battery, put it in one of my tools and "voila" it powered the tool. I put it back into the charger and fifteen minutes later with 4 LED on I tested in the tool -No Go

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