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Question about the DC9310 charger?


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This new charger is suppose to communicate with the Lion batteries on it's status before charging. If it's to hot or cold it won't work. If it's already charged it shouldn't start charging.

Well I had several new batteries to charge and accidentally placed an already charged battery back into the charger after it was sitting for about 5 minutes. I had checked the Volts on the battery after removing it and it read 18.54V. The charger didn't recognize that the battery was fully charged and continued to charge for about 5-10 minutes before it shut off. I checked the batteries Voltage and it read 19.99V. I had several new batteries and charges I was using. I tried this with a second battery and the same thing happened. Two of the charges continued to charge for another 5-10 minutes before they shut down and all the batteries ended up over 19V. A 3rd charger did not continue after the batteries initial charge, but when the batteries was placed into another charger it did.

I doubt this hurts the batteries because every battery I have ever charged reads higher than the voltage rating of the battery. I usually always check the batteries with a Digital Multimeter to make sure the batteries are up to par.

I regularly charge 12V car, motorcycle, tractor batteries that read 13-14Volts when done. I charged a 12V Ryobi battery the other day and it was 14Volts when finished. Same thing with my Makita's.

I was just supprised that the charger continued to charge the batteries after they were supposedly just charged, and if they weren't why did some of the chargers shut down early.

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What's happening within the first hour is more or less a blast charge. Enough to top the cells so you can get back to work. Leave the battery on the charger after the light turns solid red the battery goes into cell equalization mode making sure each cell is topped off. Trickle mode does not apply to the lithium batteries, at least not for the short term.

So what's happening in the first hour is getting a voltage reading of just over 18v. After 3hrs you should see even higher voltages because of cell equalization. If you take the battery off the charger once the light goes red, the cells will begin to cool, and a slight drop in voltage should occur. When you throw the battery back on, even though it's charged, it's going to begin cell equalization, thus raising the voltage again.

Charging Technology

1)  1 Hour Fast Charging

Provides the maximum charge

of the battery within 1 hour

2)  1-3 Hour Equalization

Each individual cell is fully charged to

maximize battery pack performance and life

3)  Automatic Tune-Up

A trickle charge maintains the full charge of the battery

pack when left on the charger after equalization stage

I have read other post's on here by Madtec, he may have more in depth knowledge on the battery-charger relationship.

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I my case it's 30 minutes because I'm using the DC9181 batteries but I get the picture. I think I remember reading that about every 10 charging cycles DeWalt says to leave the batteries on the charger for about 8 hours so that it can do a maintenance on the battery cells and equalize them. I did notice that the longer the battery sat the Voltage kept dropping a little during that time. I'm thinking it might be a good idea to plug these chargers into a Surge Protector with all the electronics that these charges and batteries now have.

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