wakou222 wrote:
Could I just use a 18650 in the case?
18500 would fit in place of one of those triple AAA holders - 18650 will almost certainly be too long.
If there is any such thing as a 22500 it would be even better.
LANDSURFER74 wrote:The discharge curve and the capicity of the batteries is not the issue .. the speed of the electrons either through the wire or along the outside of it (skin effect) is what makes the light bright...VOLTAGE RULES.... higher voltage, more light, less life ... it does not matter how much capacity your battery has ...1700, 2400 ,if it does not deliver voltage .... your lithium or gel cell can be the size of a house but if it is only 1.2v as opposed to a tiny aaa dry cell of 1.5 volts the aaa will always give the brightest light !! albeit for not long
You are missing the little matter of internal resistance, which limits the current that a cell can deliver. You can have all the volts you like, but if it doesn't cause current to flow it won't light anything up at all.
You mostly see that on car batteries, where they almost all deliver (nominal) 12v, but if you put a battery from an Austin mini into a Rover 3500, it can barely move the starter motor, much less spin it - it just can't deliver enough current.
As far as voltage in concerned, the problem with alkaline cells is that although they start out at a higher voltage than NiMH rechargeable cells, the voltage falls fairly quickly as the capacity is used. By the time an alkaline cell is half discharged, the voltage is LOWER than in the equivalent NiMH.
Battery manufacturers are like mustard makers - they make their fortunes on what people throw away, and that yellow glow from an alkaline powered halogen is what you get when you've used just over half of it!
So unless you replace your batteries when they are only half discharged, the average voltage over the life of the cell will be lower on an alkaline than a NiMH, which maintains it's voltage until it is almost completely discharged.
If you design the light to be most effective at a voltage that would be be typical of a semi-discharged alkaline, you'll need to put a limiter in there to avoid blowing the circuit when fresh batteries are installed.