# Sub C sized lithium ions?



## BatteryCharger (Oct 6, 2007)

I have an 18.5v drill that is filled with some crappy 1300mah NiCd sub Cs. I want to convert it to lithium ion. Does anybody sell sub C li-ions? I could fit some 18650s in there but sub Cs would fit better and probably allow more mah.


----------



## Supernam (Oct 7, 2007)

Why not NiMH Sub C's? Direct replacement, widely available (They're used in racing R/C cars). They're up to around 4200mAh, maybe more now.


----------



## barkingmad (Oct 7, 2007)

Cheapbatterypacks has 2600-4500mah NiMH sub-C's - see: http://www.cheapbatterypacks.com/?sid=851954&pgid=loosecells&chem=NIMH - lithium ion cells would be a different voltage per cell - would probably stick with NiMH - but also consider how you are going to charge these if you are changing the capacity and chemistry!


----------



## BatteryCharger (Oct 7, 2007)

I guess it depends on what the mah rating of the lithiums would be, if they exist. If it was 2500mah, that would give me a total capacity of 7500mah, and they're lighter.


----------



## BatteryCharger (Oct 7, 2007)

barkingmad said:


> but also consider how you are going to charge these if you are changing the capacity and chemistry!



18.5v li-ion chargers are readily available.


----------



## barkingmad (Oct 7, 2007)

BatteryCharger said:


> I guess it depends on what the mah rating of the lithiums would be, if they exist. If it was 2500mah, that would give me a total capacity of 7500mah, and they're lighter.



Each Li-ion cell will be about 3x the voltage - so you would have to fit 1/3 the cells or run them in parallel which is going to make charging a problem.

Also you should really use a parallel charger to charge multiple Li-ion cells.

Think I would just use NiMH - same voltage as the NiCD so same number of cells and easier to charge than Li-ion.


----------



## Supernam (Oct 7, 2007)

When you stack batteries in series, their capacity does not multiply. You could stack a hundred 2500mah li ions and still have only 2500mah. You WOULD however multiply voltage.


----------



## barkingmad (Oct 7, 2007)

BatteryCharger said:


> 18.5v li-ion chargers are readily available.



Might just be cheaper / easier buying a second battery pack or even a new drill (with NiMH cells).

18.5v would probably be 5 Li-ion in series - by the time you buy the cells, change the wiring, buy the parallel charger etc. it's going to add up to be quite expensive.


----------



## BatteryCharger (Oct 7, 2007)

barkingmad said:


> Each Li-ion cell will be about 3x the voltage - so you would have to fit 1/3 the cells or run them in parallel which is going to make charging a problem.



It would be 3 packs of 5 cells each wired in parallel. Not hard to do.


Can we please just stick to the original question? Do they exist or not?


----------



## Supernam (Oct 7, 2007)

IF sub-C Li Ions existed, and going by the price of AW's C sized cells, which cost $20/each, the total cost of 15 cells alone would be $300. All of that to get 7500mah, when you could get 15 sub-c 4200Mah nimhs for about $75 and increase your drill's runtime by 323%, and you'd still be able to use the stock charger. No brainer to me. 

But to answer the question. No, they don't exist. Question answered. Close the thread. Move on. BatteryCharger does not want any further discussion.


----------



## LEDite (Oct 7, 2007)

BatteryCharger;

The name-brand #18650 cells are more advanced cells due the much higher volume of production. they will give you the highest mah for their volume.

Two 2400 mah in parallel would give you 4800 mah. Four sets in series would deliver 16.8 Volts. 

Now, is there room for 8 of the #18650 cells in the battery case. Eight of them will cost ~$50 plus a charger.

Four D-cell lithiums(~4600mah) is another option, but their cost will be higher at $62 or so.

Larry Cobb


----------



## BatteryCharger (Oct 7, 2007)

LEDite said:


> The name-brand #18650 cells are more advanced cells due the much higher volume of production. they will give you the highest mah for their volume.



Yeah, the problem is I can only fit 5 of those in the battery case to make 18.5v. I can't fit 5 or 10 more like I could with sub Cs.


----------

