DeWalt 18v battery charger question

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Forum topic by Tedly posted 08-27-2012 04:49 AM 2690 views 0 times favorited 3 replies Add to Favorites Watch
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3 posts in 2832 days

08-27-2012 04:49 AM

A few months ago, I built a box to hold my battery chargers. I installed a 2 hour timer and when a battery would go dead, I’d pop it into the charger, crank the timer up to two hours and let it cook. Things seemed to work fine.

I did not remove the now fully charged battery, but would leave it there until I needed it at a later time. Here is the question: All the sudden, within two days, all three of my Dewalt batteries died! Flat out would not take a charge, the lite on the charger would start out slow and then start going very fast. I sent two of the batteries off to get rebuilt and then the third one quit.

It appears to me that leaving a fully charged battery in the charger without power may be causing these to quit.
I would like to know if any of you have experienced this. Perhaps it’s best to charge the battery, then REMOVE it from the charger. Had I done that, maybe my batteries would have lasted longer. If this is the case, that box that holds the chargers with the timer goes into the trash can. I will charge the battery, then remove it from the charger and not leave without having the power on.

Please advise.

3 replies so far

View Bluepine38's profile


3380 posts in 3323 days

#1 posted 08-27-2012 03:28 PM

Why the timer, I am not familiar with the De Walt, but on my Milwaukee charger, the charger shut off when
the battery is charged, and you can let the batter set there until you are ready to use in a couple of hours, or
a couple of weeks? I think the Dewalt is the same, but a quick call to their service dept should answer the

-- As ever, Gus-the 80 yr young apprentice carpenter

View Grandpa's profile


3261 posts in 2913 days

#2 posted 08-27-2012 03:39 PM

Check this out but I believe the Dewalt chargers have a “top off” feature that keeps them fully charged. Leave the power on and let the charger function as designed. On the Dewalt this is not supposed to harm the battery but should make it last even longer. Dewalt designs their batteries to have a 5 year life.

View hhhopks's profile


654 posts in 2615 days

#3 posted 08-27-2012 06:44 PM

What is the purpose of the time?
After two hours, when it turns out it shuts off power to your charger. Did I get this right?
The question that I have is, how do you know that the battery is fully charged after two hours?
The charger should be smart enough to know the battery is fully charge and basically shuts off.

Grandpa is right, but is you shut power off that would like leaving it on your tool and not using it. It should hold power for a week or so.

Though you didn’t necessary follow manufacturer’s instructions verbatim (who actually does), your batteries should fail. Sound like a Manufacturer defect to me. Is it possible that your batteries are from the same batch?

So you build a box to house your charger, ???? Is it possible for the charger shut off because of high temperature? Your box must provide the charger and battery to dissipate heat.

-- I'll be a woodworker when I grow up. HHHOPKS

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