14.4v Batteries For 12v Driver?

[Derek Arita]

I've just blown two of my Makita 12v Impact Driver Ni-MH batts. I was wondering if I could use 14.4v Ni-MH batts in this driver? Will they fit?

[Tom Veatch]

I don't know, but I doubt the 14.4v batteries would fit a 12v tool. But, even if they do, it would be like putting 144v into a 120v tool. Not as bad as plugging it into a 240v circuit, but still 20% overvoltage. Never tried it, but I don't think the tool would appreciate it over the long haul.

[Lee Schierer]

I agree your tool may run a bit faster on the higher volatge but for a short period of time before the smoke leaks out.

[Jason Roehl]

I think the biggest issue is whether or not the batteries physically fit. The higher voltage shouldn't mean a thing--it will just run faster or last longer. My 14.4V batteries, when fully charged, measure over 17V. If anything, the higher voltage will mean that the motor might run cooler (fewer amps if the motor is set up for a fixed wattage), or, the internal circuitry of the drill might prevent the higher voltage from even getting to the motor.

[Derek Arita]

Here's why I asked. I left my Makita 12v impact driver in a box for about 3 months while moving. When I finally unpacked the driver for use, I found that the batteries would not hold enough charge to allow the tool to work. Makita said that this will happen. Anyhow, 14v ni-mh batts are cheaper than 12v, so I thought maybe I could use them instead, as long as they will fit. I'm not concerned about shortening the life of the tool, as I am looking at purchasing a Panasonic Li-ion impact driver in the future. But again, the question is whether or not it will even fit?

[Chris Padilla]

Have the batteries rebuilt by PrimeCell (http://www.primecell.com/). They've rebuilt a couple Festool batteries for me and at half the cost of new ones from Festool.

[Ken Garlock]

Have the batteries rebuilt by PrimeCell (http://www.primecell.com/). They've rebuilt a couple Festool batteries for me and at half the cost of new ones from Festool.


Oh Chris, what an iconoclast. :eek: I thought items with the Festool label lasted for ever.:rolleyes:

What is a person to do? Can you provide guidance (at no cost of course)?:confused:

[Chris Padilla]

Ken,

It is a funny thing but I have two Festool drills. I have that funky shaped C12 one with the bizarre shapped battery pack and then the more normal-looking TDK one with the large battery at the bottom of the grip. The C12 is at least 1 year older than the TDK and its batteries are fine. BOTH of my TDK batteries finally died at about the 3.5 year mark. Go figure....

[scott spencer]

I've been running 16.8V Ni-Cads in my 14.4V Craftsman drill for over a year. The batteries last longer and the drill has more power. Not sure about the long term damage to the drill, but don't really care either.

[Mike Henderson]

I've been running 16.8V Ni-Cads in my 14.4V Craftsman drill for over a year. The batteries last longer and the drill has more power. Not sure about the long term damage to the drill, but don't really care either.
I'd have to go review my motors book, but I think the speed of a non-series wound DC motor varies with the applied voltage. That would lead me to believe that the trigger mechanism (variable speed) is actually a voltage control. So most of the time you're not applying full voltage (unless you have it fully depressed). And the effect of using higher voltage batteries would be that the motor would have a higher "full speed". You would draw more current at full load and full speed so you could exceed the capacity of the battery under those conditions.

Maybe someone more familiar with DC motor theory could confirm or correct my guesses.

Mike

[Byron Trantham]

Have the batteries rebuilt by PrimeCell (http://www.primecell.com/). They've rebuilt a couple Festool batteries for me and at half the cost of new ones from Festool.


I have been using PrimeCell for a couple years now and they are they greatest. Their web site is a bit convoluted but once yo get through it you will be happy. ;)