Why different batteries for Drills?

[MrToolJunkie]

OK...so this is probably a stupid question but I am going to ask it anyway -- just curious why there are so many options for drill batteries?  Is it purely to save on weight? or is it purely cost?  I get that the 18v is a newer drill, but why would someone opt for a 12v when the 15v is not much more in terms of weight and really not that much more in terms of cost?  For less than 6 ounces, why would someone opt for the 15v instead of the 18v?  To me the CXS makes sense for the small category and I totally get have "C" and "T" styles for handle configuration but I am curious why some folks opt for 12 volt instead of higher...  Curious to hear other views on this...it is not a debate on the merits of Festool drills -- just on the reasoning and logic behind the different voltages and why some users would pick a 12v over a 15v or 18v (if getting a "T").

Scot

 

[peter halle]

I use my 12v drills the most.  Lighter and frankly do what I need.  Use the 15 when I need more oomph.  Could I get by with one bigger?  Yes.  But I do jobs where I want two drills / drivers.  Then I use 12 to drill - plenty of oomph - and then I use 15 to drive.

Just me.

Peter

 

[JUDOKA]

Hi , i use my CXS as a pocked driver all day long ,I also picked the T15 cause it is a little lighter than the T18 .

 

[Coen]

Price, Weight and less battery failure since the number of cells is lower (3 in the 12V, 4 in the 15V and 5 in the 18V)

(It's really 11.1 Volt, 14.8 Volt and 18.5 Volt btw...)

 

[GregBradley]

Can't change chemistry. Lithium Ion cells are 3.6 volts. There is some room for exaggeration because that technology does not have as flat of a voltage/discharge curve as Lead/Acid, Carbon/Zinc, NiCad, NiMh, etc but:

It is 10.8v, 14.4v, and 18.0v.

Other Lithium Ion tools commonly are 3.6v, 21.6v, 28.8v, and 36.0v.

The 10.8v tools are exaggerated and labeled "12v max". 14.4v is sometimes called 15v. Festool may call the tools T-12, T-15, and T-18. but they do spec the voltage accurately so a T-12 is called a 10.8v drill.

In an interesting twist, Hilti makes the most powerful US 18v Li impact driver very simply, by using a 6th cell and making it 21.6v.

 

[Coen]

Li-ions are often labelled 3.7 V 

Fully charged three cells easily top the 12 V, since they come off the charger (at least, single cells do) at 4.2 Volts each.