# Batteries dying if left in the cordless tool?



## General (Dec 11, 2010)

I have the small Makita 10.8V Impact Gun that I love. One issue that I noticed is that if I don't use it for 2 weeks or so, the battery that I left in the drill seems to be dead, BUT the second battery that weasn't in the drill seems to be fully charged. 

This leads me to believe that leaving the battery in the drill causes it to discharge. FWIW, I lock the drills trigger so it can't accidentally be turned on.


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## PaliBob (Jun 11, 2008)

Cold weather kills the charge in Li-Ion batteries. If the second battery has been kept in the same environment as the battery in the tool, then the battery may be marginal. You could switch batteries and repeat the test to see if both batteries exhibit the same condition.

Makita, when they label their Tools as 10.8 Volt, seem to be the only manufacturer that has remained honest about the actual voltage. The other Tool makers have labeled their 3-cell Li-Ion tools as 12 Volt. The voltage of a Li-Ion cell is 3.6V, so three cells make 10.8 Volts *Not 12V*.

Bosh, I think, was the first one out with a compact 10.8 V Li-Ion tool, but when the competition started calling their new models 12V Tools then Bosh switched to calling their 10.8V tools, 12V tools. The justification was that on a new fully charged 3-cell Li-Ion battery pack, the open circuit voltage can hit 12V. The New Bosh 12V batteries are duplicates of the ones they originally labeled as 10.8 V.


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## General (Dec 11, 2010)

PaliBob said:


> You could switch batteries and repeat the test to see if both batteries exhibit the same condition.


 I forgot to mention that, it happens with BOTH batteries. Whatever battery is in the drill seems to die after 4 screws, but the battery that was sitting right next to it and was charged at the same time will seem to have a full charge.


> Makita, when they label their Tools as 10.8 Volt, seem to be the only manufacturer that has remained honest about the actual voltage. The other Tool makers have labeled their 3-cell Li-Ion tools as 12 Volt. The voltage of a Li-Ion cell is 3.6V, so three cells make 10.8 Volts *Not 12V*.
> 
> Bosh, I think, was the first one out with a compact 10.8 V Li-Ion tool, but when the competition started calling their new models 12V Tools then Bosh switched to calling their 10.8V tools, 12V tools. The justification was that on a new fully charged 3-cell Li-Ion battery pack, the open circuit voltage can hit 12V. The New Bosh 12V batteries are duplicates of the ones they originally labeled as 10.8 V.


 On Makita's website they promote some of the 10.8V tools as "12V Max". I guess everyone is playing the game.


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## PaliBob (Jun 11, 2008)

Wow! That sounds like neither battery has enough charge to drive more than four screws. Am I hearing that right?
.


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## Ron6519 (Mar 28, 2007)

Then the lesson learned is leave the batteries out of the tool. I'll have to try that with the 18v Dewalt. But they stay in the truck regardless of the time of year. I plug them in as soon as I get to the job.
Ron


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## General (Dec 11, 2010)

PaliBob said:


> Wow! That sounds like neither battery has enough charge to drive more than four screws. Am I hearing that right?
> .


Yes, if left in the gun for a couple weeks. The battery that is not left in the gun has a good charge.


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## General (Dec 11, 2010)

Ron6519 said:


> Then the lesson learned is leave the batteries out of the tool.


 That's not a lesson, that's a band-aid. If other people's Makita's aren't doing this, then there is something wrong with mine.


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## SDC (Feb 18, 2009)

Those Makitas, even when the trigger is locked still allow the light to activate. If it is bouncing around in your truck it may be hitting the trigger enough to wear it down. 
I have those drill and have not seen the same issues.


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## Thurman (Feb 9, 2009)

For what it's worth: I have multiple DeWalt tools which use 18v batteries. I have found that if I leave any of these tools with a battery in them, they will discharge. As you stated, I have left a tool lying on a workbench next to a marginally charged battery. The battery in the tool dies, and the battery not in a tool stays at about the same charge. I now have a habit of pulling my batteries out of tools at the end of each work day. Actually in my work trailer I have a space for all of my DeWalt batteries and can tell if on is not in it's proper place before locking up.


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