Repowering an old C12

[Dan Lyke]

So I've got this old Festool C12, the kind that just takes NiCd or NiMH batteries, and both my NiCd batteries have worn out. I've got a new NiMH battery that's rockin' gangbusters, but another one is another $80 or somesuch, and I have a boat load of Milwaukee M12 LiIon batteries lying around.

I didn't think it was reasonable to expect an LiIon battery to put out 12v (I thought the cells came in 3.6v increments), but I laid a voltmeter across 'em, and viola voila, 12V! I know they're doing amazing things with battery technology these days, so...

That kinda got me to thinking: I'm handy with a soldering iron, I wonder if I could use the old NiCd cases as plugs, and mill a little something to let me plug the M12 batteries into the old case, which could then plug in to the bottom of my C12 drill.

Has anyone tried another power source for the C12? I know Rick Christopherson was using a C12 to drive the Jupe table he built, but he doesn't go into power supply issues there much. I haven't looked at how much internal resistance is likely to vary between the NiMH and NiCd batteries (with no load the Festool NiMH battery read 14v), but is it worth pursuing this at all, or am I just gonna get the "beep" that indicates that the current got drawn too low?

Any insight?

>

 

[semenza]

I am thinking the problem would be that the NiCd C12 won't run on LiOn.  ???

Seth

 

[AlexThePalex]

Yeah, you can't run a tool that's meant for NiCD/NiMH with LiOn batteries.

LiOn batteries are a bit more delicate, so they need a special monitoring circuit to get them working properly. NiCD tools lack such a circuit. You could make the C12 drill turn, but it will ruin the LiOn battery very quickly.

 

[Jonhilgen]

Have to say that I just purchased replacement batteries for my c12 and I'm ready to throw the drill and the batteries in the trash.  I can't do more than six pocket holes with my kreg jig before it dies.

Rant over.

Jon

 

[peter halle]

Have to say that I just purchased replacement batteries for my c12 and I'm ready to throw the drill and the batteries in the trash.  I can't do more than six pocket holes with my kreg jig before it dies.

Rant over.

Jon

Were they genuine Festool batteries?  If so, call Festool.

Peter

 

[WarnerConstCo.]

Have to say that I just purchased replacement batteries for my c12 and I'm ready to throw the drill and the batteries in the trash.  I can't do more than six pocket holes with my kreg jig before it dies.

Rant over.

Jon

I am running a couple 5 year old battery's and I just bored 10 lock sets in oak doors and did not even go through one battery  

 

[mastercabman]

Also,you will need to get a new charger.

 

[mastercabman]

Have to say that I just purchased replacement batteries for my c12 and I'm ready to throw the drill and the batteries in the trash.  I can't do more than six pocket holes with my kreg jig before it dies.

Rant over.

Jon

Are the new batteries bad?  Or are you talking about the old ones?

 

[Dan Lyke]

I know that I'll need to use the M12 charger, that I can't use the Festool charger, the question is really: Has anyone tried hooking up a C12 to another power source? How much current does it draw? At what voltage does it decide to beep and tell me the battery is dead?

Thanks.

 

[AlexThePalex]

Dan, I don't think you get it. It's not just about the charger. It's also about the drill. The drill needs to have a special circuit built inside it to be able to use LiOn batteries. And that circuit is not for the benefit of the drill, it is for the benefit of the LiOn batteries. As I said before, LiOn batteries are delicate. They're not as easy as NiCd batteries. LiOn batteries need to be emptied in just the right way, and the special circuit takes care of that. Without the circuit, the batteries will die very soon. For instance, a LiOn must never be discharged beyond a 15% charge, if I recall correctly. The source that drains the battery needs to have a circuit inside that checks for that. If you discharge the battery beyond 15%, the battery gets damaged and you loose capacity.

 

[Dan Lyke]

Right, so does anyone know at what voltages and current loads the drill makes the decision to stop running? I guess I should have phrased my question differently.

 

[GregBradley]

It is a characteristic of Li cells for the voltage to vary during use. The fact that 3 cells test as 12v has nothing to do with the FACT that it is a 10.8v battery. They are just called 12v Max. NiCAD, NiMH, LiIon batteries each have different advantages and disadvantages. The charging and discharge characteristics of NiCAD and NiMH are similar enough that they are mostly interchangeable on tools. LiIon are completely different.

Your solution is to replace the cells in your battery packs. In other words, rebuild you battery packs or have them rebuilt.

 

[JPW]

Maybe one of these can help?
http://www.hobbyking.com/mobile/viewproduct.asp?idproduct=19945&type=&idparentcat=156