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Timer for cordless tool battery charger

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  • Timer for cordless tool battery charger

    I have suspected for a while that battery life is shortened if the battery is left on the charger. I just talked to the Ryobi tech, who "doesnt recommend that the battery be left on the charger." He could give no reason why. I have no "battery protocol discipline" and just leave them on the charger until I need a charged one. I suggested that I put my charger on a timer and he agreed that this would be a good idea. This was prompted, by the way, when I paid $129.00 for a single Li-ion battery and "special charger."
    Anyone suggest a simple 60- to 90-minute timer that I can plug my charger into? PULEEZ dont recommend an "elctronic wonder with X daily functions and Y on-off intervals." I just want to slap a battery in the charger and hit a GO button. Duffy
    Duffy, Gatineau, Quebec

  • #2
    Think any inexpensive timer such as the ones you use for lamps would work, just don't install the start pin and set time 2 hours from the off. But I'm wondering if this would have the reverse effect by slowly draining the battery when it's not connected.
    Cheers, Bob


    • #3
      Hmmm...I dunno. I would find someone with more specific knowledge of the internals and relative "intelligence" of your charger than "the Ryobi tech". I have a Dewalt 14.4 v drill and impact driver. The drill is over 11 years old and the original batteries are not great....but still going. They are traditional NiCd's which are perhaps the most problematic battery construction as compared to some others available today. Their charger rapid charges and then does an occasional "keep warm" (my term not theirs) to keep it charged. They do recommend keeping them in the charger, and I have a hard time arguing with 10 years of use--even if the original batteries have very limited life now.

      If you cycle such a charger off and on, I found that it tries to go into "full charge" least for a little bit until it figures out the battery is fully charged. I would think that regular power cycling could be self-defeating in a case such as this.

      Paul Carpenter
      Mapleton, IL


      • #4
        If you have an intelligent charger, and except for the very low-end cordless tools, most are now intelligent, I would leave it pugged in. It should go into a trigger charger mode and this should not cause harm.

        If you don't use your cordless for weeks at a time, then it may actually be better to leave it uncharged until the time that you need it.


        • #5
          agree, my chargers go into maintenance mode and just keeps them in tune.
          The batteries reange between 12 and 5 years old and still work fine.

          I have a LOT of cordless tools, mostly porter cable 19.2v, with a dozen batteries and 4 chargers for the PCs alone. Only reason I've had for replacing batteries has been when I physically break them.

          With nicads I've noticed that if you routinely remove the battery after use and put it back on the charger it shortens the life, I only recharge when the battery is dead, and my batteries have lasted.



          • #6
            Battery games

            I have 5 NiCads for assorted DeWalt (DW) 18 volters. I am a DIYer, not a pro, and queried DW how to deal with the charge it, use it a bit and then recharge or not (realising that several weeks may pass until the battery pack is used again).

            DW states that the best is to charge all batteries (preferably leaving connected to the "intelligent charger" -their terminology - to allow the charges to be equalized in each cell of the battery) at one point in time and use each in turn until it shows an *initial* drop in performance. Running it to the point of exhaustion is not recommended. While, in theory, it can be re-charged at that time I believe that a cool-down period won't hurt before it is plugged into the charger. At this point, I have about 43 months on the oldest battery & still going strong.

            Fwiw, the pros on the Fine Homebuilding forum (hope mentioning this is ok) have been known to open the battery case & replace the cells instead of buying a new battery. There are businesses that offer this service or the cells can be bought and soldered by a diy'er)


            • #7
              Instructions with my Mikita Ni-MH.

              1. Charge when performance decreases.
              2. Don't charge when already charged.
              3. Charge every 6 months.

              These batteries seem to have full power until the last few revolutions of a drill.

              I let the battery cool before charging in case the charge sensors sense heat in the battery package.

              I date the batterers after charging to comply with 3.

              Ni-MH's didn't grow up with lead acids or Ni-Cads, they weren't pen pals or go to camp together. They don't speak the same language or date the same girls.


              • #8
                Thanks for the advice guys. I dont suppose that I go more than a day or two, (or three,) without using a cordless something-or-other. I have a 9.6V Makita, a 14.4V Mastrcraft, (Canadian Tire,) and an 18V Ryobi. I am the first to admit that these are NOT top-of-the-line tools, but I dont make a living with them, and they seem to suit my needs. I threw away a Milwaulkee 12V drill when I was told $79.00 for one new battery! Dammit there are only a few companies making battery cells, and there CANT reasonably be THAT big a difference in either quality or value. Duffy
                Duffy, Gatineau, Quebec


                • #9
                  What I've always wanted to know is how these chargers act if the garage is unheated and the temps go to -20F with battery in place.



                  • #10
                    It won't be easy to find out if the charger drains the battery when the battery is in and the power cord pulled or power disconnected, but there were some brands and models where this did happen. Unless the instructions explicictly state that the battery can be left in while the charger is unplugged, I'd be taking the safe route and pulling the battery after full charge. My old boss used to leave a battery in the charger while the light switch in the shop would also kill power to the charger. Those batteries were shot after 2 yrs.

                    'ryobi tech' sounds like a guy who doesn't really know the facts and was just spouting off, like so many so-called techs and specialists seem to do. I would bet that for every 10 cordless tool dealers or repair places, you'd be hard pressed to find 1 that could give you the information you need. Unless you're willing to be a test monkey, you'd be better off forgetting about putting a timer on the chargers. Better would be a timer that sounds off to alert you that it's time to remove the battery from the charger. Just my opinion-
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                    • #11
                      I would go for a timer especially for NiCd as they will definately have a shorter life if overcharged. These cells have an excess of electrolyte to accomadate an amount of over charging if this is depleted then the cell will slowly loose capacity over time.
                      I built a charger for a couple of my NiCd batteries which required a 5 hour charge and was not in the habit of remembering that I had left them on charge and with another 2 drills(both the same) I found the batteries smoking just in time to avert a fire. These were supposed to turn of the cgarge after 1 hour but didnt still both imes I got more back than I paid and invested the money in a more reputable make(not sure what that is)
                      The timer I used was an elecromechanical timer with an electric motor and gears that could go upto 24 hours not sure of the make except that it was of German origin and quite reliable even if old.
                      The whole problem of one shot timers has always bothered me in that in this world of electronics they are not very prevalent.

                      I have tools I don't know how to use!!


                      • #12
                        I haven't read the entire thread so someone may have said this.

                        You should not leave the drill battery on the charger all the time. If you feel even the slightest warmth to the battery case you are cooking off your battery. You should have two batteries and ONLY charge when they need it. What's the difference if you own 2 batteries and they last 10 years (as in my Bosch drill) or you own one battery and it last 1 or 2 years?

                        I do leave my ATV, lawn mower and medical equipment batteries on the charger constantly but they are "battery tenders". They sample the battery voltage ever hour for a second. If the voltage slips a certain amount they will gently bring it back up to voltage and shut off. Napa auto parts sells them for $32.00 and they work fantastic and batteries seem to last forever because they never cook off.

                        We had 3 batteries assigned to each of our 22 TV news cameras used damn near round the clock and they lasted easily for 5 years by simply running them down before charging.
                        Last edited by Your Old Dog; 06-29-2008, 08:58 AM.
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                        • #13
                          I bought one of those 12-hour wind-up timers that are used for whole-house fans and wired it to a charger outlet. Spin the knob to set it for a few hours and walk away. Have seen other stories about batteries catching fire when left in the charger and want no part of that.


                          • #14
                            Originally posted by jdunmyer
                            I bought one of those 12-hour wind-up timers that are used for whole-house fans and wired it to a charger outlet. Spin the knob to set it for a few hours and walk away. Have seen other stories about batteries catching fire when left in the charger and want no part of that.
                            where you get it ??


                            • #15
                              I bought one of those timers at the local hardware store, but they had to special order it, as their in-stock units went to only 1 hour. Had to go to the Internet for the second one, as the h/w store could only get digital units after that first one, and the ones they got in were all faulty. Plus, too complicated in their operation for what I wanted. I don't remember where I ordered it from, just did a search. Actually, I'd almost bet that the big-box home improvement stores would have them, for whole-house fans. The ones I have are exactly like that installed in my house for that purpose.

                              The first one I installed wasn't for the battery charger(s), but for my cartridge case cleaner. I load the machine, twist the knob to "2 hours" or so, then leave, not having to listen to the thing run, nor forgetting it for many hours.