How would 4 x Alkaline C cell batteries go running a driver such as this. Would the batteries handle the current draw without leaking and what sort off run time would you expect on hi? Or would there be a better driver available running 3 C cells at around 2.8 to 3 amps?
Hi,
Couldn’t you get AA-to-C or AA-to-D adapters, and then the appropriate number of dummy AAs plus a 14500 battery, or build a spacer with a dowel and a bolt, and use an 18650, and that’d be guaranteed to work with that driver?
I want to keep this simple. No lithium ion and just everyday batteries. My brother bought me back two lights from the states and l want to build him one that he can just use and get batteries from anywhere. I have spare tubes so it would be no problem modifying the light to use 3 or 4 batteries that I hope would give a reasonable run time.
Perhaps the best option is NiMH C cells. Yes, I know you said you want alkalines. But let’s face it. At anything around 3A, alkalines are going to be highly marginal. They’re just not designed to put out that kind of current for any period of time. Even at 2A (which is about what you get with the stock driver), an alkaline C cell is running close to the edge of its existance. NiMH C cells, on the other hand, are high amperage powerhouses that could easily supply more current than the light could ever use.
This is what I need to know. Thanks. So maybe drop the current to the led to 2 amps would be better on Alkalines?
2A would certainly be better, even if not ideal. This would just be leaving the light as it is. And speaking of that, if you want to run alkalines, leaving the light the way it is is your best course. If you want ANYTHING more powerful, you are going to NEED to run either NiMH or Li-Ion.
The alkaline datasheets from c cells I have seen don’t show currents higher than 1 A.
With 1 A you get about 1Ah until 0.8V….
Edit: I checked the duracell datasheet and it shows about 0.5 service hours at 2a discharge until 0.9V
So go for nimh, these have almost constant capacity no matter which discharge current.
What about using a driver which is direct-drive on high? That way you'll get whatever current the cells can put out.
-Garry
Thanks Werner. So the C cells arent going to be much good for anything over one and a bit hours and at $12.00 for four at the local supermarket its not looking good.
I wonder what plan B is?
I know you said, that you wanted to use “Normal” batteries, but I have been thinking about using these Sub-C Sanyos in a Defiant, and put more in…just a thought:
Found these, supposedly High Amp, but you know the story…
All thoughts good or bad are good thoughts. Thanks.
Alkalines are not for high powered lights. If you have to use easy to find cells like Alkalines, then you might as well go with something like an XP-g or XP-e and power it with about 500mA. Well… that’s more realistic for Alkalines. If rechargeable cells are out, just make a small light with lower power.
Told you that you needed to have him get some Maglites for you to mod. 
EDIT: Actually, something like a Maglite XL-50 would be a great small light that would use Alkalines.
Three fresh alkaline Ds (I have not played with Cs, so if you know them better than I do adjust these numbers accordingly) will only do right at about 1.8A, direct drive, into an XML. Though I'm guessing the voltage sag pulls them down to the point that it's running at less than optimum Vf which is what limits the total current... I haven't checked voltage under load in any of the DD 3D Mags, but that sounds like a plausible explanation. Four would probably sag to a point that still allows a decent Vf which will allow more current, so that would possibly be an option for using a conventional driver. But with only three cells a driver is really pointless unless you want/need the multiple modes.
Thanks comfychair. I’ve decided with a lot off help from the members here that it isnt going to work. Not sure what I’m going to do. I’ve enough other things to worry about at the moment so I will look at it in the future. Cheers.