Mag* C-D battery options.

[bryan24]

I was looking for a form factor that is easy to hold but provide descent power capacity. The D-cell mag-light is king but due to not being able to get a full grip on it I would drop it 2-3 times a night. Someone mentioned that a C-cell is better for smaller hands and since I have had my C-cell only dropped it twice(when I hit my hand on something). C-cells have been somewhat Impotent so I was looking for a replacement. If they'd come out with a lithium cell the size of 2C-cells and 3.7v like the 18650 with higher mAh that would be ideal.

I have found a solution to my problem for the meantime(it dose waist some space though). Menard's has 3/4" PVC nipple(the12" length will work for 3-4 18650's SKU 38102) that fits 18650's perfectly. The outside has to be sanded down about .5 mm to fit the C-cell mag-light body. Three 18650's fit almost perfectly (2mm shorter) in a 4C mag and would provide 11.1v instead of 4.8v. Also a 5C cell can be used the same way to hold 4 18650's (15mm longer) if you remove the spare lamp and move the spring back to the spare lamp section. this gives you 14.8v (16.2v over-voltage) instead of 6v. with this set up I could almost drive 4 CREE's in series with only current regulation. might have to tweak a board to do this though.

Here is some of my rough calculations just using specs@1A to keep it comparable:

C-cell configurations
(4-cell light)
18650 3.7v@2500mah =9.25WH power density 3(27.75wh)@11.1v (Trustfire)7.5h@1A
C-cell 1.2v@2500mah = 3WH 4(12Wh)@4.8v (energizer)10h@1A
C-cell 1.2v@6000mah = 7.2WH 4(28.8Wh)@4.8v (accupower)24h@1A
(5-cell light)
18650 3.7v@2500mah =9.25WH power density 4(37wh)@14.8v (Trustfire)10h@1A
C-cell 1.2v@2500mah = 3WH 5(15Wh)@6v (energizer)12.5h@1A
C-cell 1.2v@6000mah = 7.2WH 5(36Wh)@6v (accupower)30h@1A

D-cell configuration
(5-cell light)
D-cell 1.2v@11500mah = 13.8Wh 5(69Wh)@6v (accupower)57.5h@1A
(3AA to 1D converter)
3AA@2500mah 3.6v@7500mah = 27Wh 5(135Wh)@18v (energizer)37.5h@1A
3AA@2900mah 3.6v@8700mah = 31.32Wh 5(156.6Wh)@18v (accupower)43.5h@1A

 

[2xTrinity]

I was looking for a form factor that is easy to hold but provide descent power capacity. The D-cell mag-light is king but due to not being able to get a full grip on it I would drop it 2-3 times a night. Someone mentioned that a C-cell is better for smaller hands and since I have had my C-cell only dropped it twice(when I hit my hand on something). C-cells have been somewhat Impotent so I was looking for a replacement. If they'd come out with a lithium cell the size of 2C-cells and 3.7v like the 18650 with higher mAh that would be ideal.

There are Emoli cells, basically 26670 cells from Milwaukee drill packs. Only about 3AH, but they are inherently safe chemistry, and designed to handle much higher currents than ordinary LiIons. You can fit 3 in a 4C.

The other option is AW C-Cells, 3.3Ah, 3.7V Protected LiIons, 26540 (4mm longer than ordinary "C" cell). I am running an ROP Incan off of two of those in a 2C, the only mag that can fit in a jacket pocket. Those are slightly longer than an ordinary C, but by cutting down the spring, and thinning the switch assembly with a dremel tool it's possibel to make extra room for them.

I have found a solution to my problem for the meantime(it dose waist some space though). Menard's has 3/4" PVC nipple(the12" length will work for 3-4 18650's SKU 38102) that fits 18650's perfectly. The outside has to be sanded down about .5 mm to fit the C-cell mag-light body. Three 18650's fit almost perfectly (2mm shorter) in a 4C mag and would provide 11.1v instead of 4.8v

This is a good solution to run things like the 1185 lamp for 40 minutes. Or you can load it up with 3x Emoli and run for over an hour, or with a voltage regulator all sorts of LED builds.

 

[Power Me Up]

D-cell configuration
(5-cell light)
D-cell 1.2v@11500mah = 13.8Wh 5(69Wh)@6v (accupower)57.5h@1A
(3AA to 1D converter)
3AA@2500mah 3.6v@7500mah = 27Wh 5(135Wh)@18v (energizer)37.5h@1A
3AA@2900mah 3.6v@8700mah = 31.32Wh 5(156.6Wh)@18v (accupower)43.5h@1A

You've actually got a fairly major mistake there - In the 3AA to 1D adapters, you're multiplying both the voltage and the capacity by 3. You should only multiply the voltage when they're connected in series or multiply the capacity when they're connected in parallel. Because of this, your final numbers are 3 times higher than they should be.

 

[bryan24]

Doh I figured they were outa wack. thanks. I didn't think a flash light would run all week

 

[bryan24]

There are Emoli cells, basically 26670 cells from Milwaukee drill packs. Only about 3AH, but they are inherently safe chemistry, and designed to handle much higher currents than ordinary LiIons. You can fit 3 in a 4C.
.

Where are these Emoli's purchased and how would you recharge them? What voltage and lenght?

 

[2xTrinity]

Where are these Emoli's purchased and how would you recharge them? What voltage and lenght?

http://www.candlepowerforums.com/vb/showthread.php?t=178188 -- here is a thread on CPF, where you can buy cells freshly extracted from the drill packs. Emoli does not cell these directly to individuals.

3.7V 2700mAh.
20A rated continuous current

I was mistaken before, they are actually 26700 cells -- that means 26mm diameter, 70mm length, and "0" means cylindrical.

Also for sale on that thread is the A123 chemistry, which runs at 3.3V and even higher currents -- 70 Amps continuous.