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Thread: Dewalt charger
08-13-2005, 06:01 PM #1
I have a dewalt 12volt cordless drill. The charger makes a very high pitched noise and it does not charge anymore. The "hi pitched noise" and the "not charging" happened at the same time. I dont think a new charger would cost alot, but I would like to try and fix this one first. I have 120 volt main power and about 8vdc at the terminals where the battery plugs in. When I check the terminals (with my meter) without the battery plugged in, I dont get anything. I plug the battery in and I get about 8vdc. I thought that maybe some of you may have experienced this same problem and know exactly how to fix it. Jeff
08-13-2005, 06:17 PM #2
08-14-2005, 03:22 AM #3
Most of the chargers now are 'smart', meaning that they won't actually power up into the battery if the battery voltage isn't at least in the ballpark. You might want to check the voltage on the 'dead' battery to see if it's near the level of a discharged battery, or if it's substantially lower than that. If it's lower, the charger might be ok, but just responding to a 'bad' battery. The whine you hear would likely go much higher in frequency if the charger was actually delivering a charge into the battery. If that's the case, you wouldn't hear it. You're either hearing the charger idling or it has a failure, probably a weak capacitor, but could be many other things.
08-14-2005, 11:30 AM #4
Yep, good advice.
What model is it?
If yours has a light, it should indicate a bad pack by a quick flash. Even older ones like my old 9106 do that.
Try it with your other battery...you did get two, right?
trying to measure is unproductive. It won't operate the same into an "open" as with a battery. Even with a battery, voltage is determined by the battery, as current is input from the charger.
Repair is unlikely to be productive, unless you know that type circuit well. They are not old simple chargers anymore.
I recently thought mine was bad. Turned out it was BOTH batteries, which would not charge past 10.8V although tehy are 14.4 volts.... I tried charging them separately over in my electronics shop area....no-go.
It was cheaper to buy a new drill with charger and two batteries than to get two more batteries....considering that the old drill is 10 years old or more.... and may not last forever....
Kudos to De Walt, the new batteries fit the old tool, and the new charger would charge the old batteries if they were good. So I can potentially replace some failed cells ($20 from Digi=key for 10 size "SC" with tab batteries) and have more "good" batteries.
08-14-2005, 12:29 PM #5
I just had to replace my charger, $52!, not much to it. I might had been smarter to buy a whole new kit with 2 batteries etc.
08-14-2005, 03:37 PM #6
I appreciate everyones input. Both batteries are good. The charger is a dw9118 and the led flashes as if everything is ok. I was just hoping I could simply swap out a faulty component. A bad capacitor, transistor or triac would be easy to fix. The trick is determining which component is bad. As you all know its always a good feeling to fix things yourself and gives you a sence of accomplishment. The alternative is obvious, so I'll probably look on ebay or something.
08-14-2005, 10:08 PM #7
I bought a B&D 12V charger to replace my DeWalt because it was half the price. Batteries/chargers are interchangable (for the "old style", at least).
If I plug a bad battery pack into the charger, it will emit a high-pitched whine for about 30 seconds before the LED starts flasing the "bad pack" sequence.
08-14-2005, 11:54 PM #8
So just how do you KNOW "both batteries are good"?
That's what I thought until I tried it and found they BOTH wouldn't charge past 10.8 volts or so. Even on the NEW charger, and they don't trigger the "bad pack" signal on either one.
Sounds like yours, like mine, have some shorted cells.
I finally tried to charge them with a haywire hookup over on the electronics bench, and they STILL wouldn't go past 10.8 as far as a held charge. They would indicate a little higher,12V, under a 1A charge, but would drop rapidly back.
The charger may be bad, but it is by far the most reliable part of the system.
08-15-2005, 01:09 AM #9
At Home Depot recently, I noticed that Ryobi 18 volt rechargeable batteries are on sale for $39.95 a pair. I considered buying a pair just for the cells. They could be used to replace cells in defective batteries at a much lower cost that just buying the cells.
08-15-2005, 10:17 AM #10
If you wanna replace cells, don't buy a pack, get the tabbed ones from Digi-Key electronics.
About $18 plus shipping for 10 "SC" size tabbed cells, IIRC that is for 1.5 AHrs (1500mAHrs).
08-15-2005, 11:01 AM #11
Two batteries at $39.95 - each contain 15 1.5 ah cells. So that is 30 cells for 1.25 each. No shipping. Just an alternative.