Battery Charger Blues

I made the mistake of buying a Chinese-made battery-operated electric drill,
which worked fine until I tried to charge the batteries. I emailed the
manufacturer but needless to say, I have received no response.
The rechargeable batteries are rated at 18V. The charger consists of a
small receptacle with a few electronic components in it, and a plug-in
transformer 120v. AC, 60 Hz to 22v. DC, 500mA, 11 VA. The transformer does
not get warm no matter how long it is plugged in, and the pilot light on the
charger that should indicate when it has charged the battery, never lights.
I've spent a couple of hours googling for transformers of similar
specification, with no success, and I refuse to spend more for a variable
voltage transformer than I've paid for the entire drill. Any suggestions as
to a commonly available transformer that would get the job done, even if
slowly?
Bob
Reply to
Bob Tyrka
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I made the mistake of buying a Chinese-made battery-operated electric drill, which worked fine until I tried to charge the batteries. I emailed the manufacturer but needless to say, I have received no response.
The rechargeable batteries are rated at 18V. The charger consists of a small receptacle with a few electronic components in it, and a plug-in transformer 120v. AC, 60 Hz to 22v. DC, 500mA, 11 VA. The transformer does not get warm no matter how long it is plugged in, and the pilot light on the charger that should indicate when it has charged the battery, never lights.
I've spent a couple of hours googling for transformers of similar specification, with no success, and I refuse to spend more for a variable voltage transformer than I've paid for the entire drill. Any suggestions as to a commonly available transformer that would get the job done, even if slowly?
Bob
Reply to
Brian
1: measure the charger voltage with a volt meter.
2: make sure the battery is making contact with the charger terminals
3: use an auto tail light to simulate a load. briefly bridge the tail light across the charger. it should glow brightly.
4: sometimes there is a device in the battery which senses heat. this opens up when charge is complete. this could be bad on your battery pack.
Reply to
TimPerry
In addition to some of the ideas mentioned by others, I'll ask just how far discharged is the battery. Some small battery chargers are designed to *not* turn on unless they see a certain voltage from the battery. It is to help prevent reversed polarity and such. A little-league score-board controller we have that is battery operated will not charge at all if the scorekeeper leaves it on overnight. We 'jump-start' it by using temporary hookup from a car's cigerette lighter. Once the charger 'sees' a voltage of the correct polarity, it starts charging and brings the battery up to full charge.
daestrom
Reply to
daestrom
A little-league score-board controller we have that is battery operated will not charge at all if the scorekeeper leaves it on overnight. We 'jump-start' it by using temporary hookup from a car's cigerette lighter. Once the charger 'sees' a voltage of the correct polarity, it starts charging and brings the battery up to full charge.
daestrom
Thanks for all the suggestions I received. Unfortunately, I don't have the patience or the equipment available to do troubleshooting and the DeWalt site doesn't show transformers as separate from the charging mechanism, as is the one I own. One of my batteries did have a slight charge left, but it too failed to charge. Does anyone know of a transformer I might buy that will work for my drill? Would an 18V. 500mA to 1A DC output charge my batteries?
Bob
Reply to
Bob Tyrka
Yes, but you need to add a 470 ohm 1 watt resistor** in series. And it will take a little over 2 days to full charge a completely discharged* pack. (* - "completely discharged" as used here means your 18 v pack is depleted to about 13.5 - 15 volts. "Completely discharged" occurs when the battery operated device shows degraded performance - a drill slows dow, a flashlight gets dim, that kind of thing.)
** = assuming a regulated 18 V adapter. If it is not regulated, you need a bigger resistor. Use 2 470 ohm, 1 watt resistors in series with an unregulated 18v supply. A second assumption is that the battery pack is rated at 1500 maH.
It should be noted that the above appraoch does not yield the best treatment of your battery pack - a properly designed charger requires far more than an 18 v adapter and a resistor. But is cheap, you can do it without test equipment and a lot of effort, and it won't overcharge the pack. One *major* warning: you *must* ensure that the positive output from your adapter goes to the positive side of the battery.
Ed
Reply to
ehsjr
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and the DeWalt
Reply to
TimPerry
050626 2236 - Don Kelly posted:
My DeWalt charger for my battery drill was assembled in Mexico...
Reply to
indago

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