Rayovac has been hitting bullseyes lately. So has WalMart. (I do not own stock in either company). I was at my local WalMart last week and I made a list of all of the flash lights in the sporting goods department that had a run time over 40 hours. I counted 7. Most of them were Rayovac and all of them were under $16.00. So why am I doing another Instructable modifying a flashlight to make it run longer on a set of batteries? The longest run time flashlight was a 52 hour, 9 lumen flashlight for $2.50. It is a modern version of the old style flashlight with the slide switch on the side. The slide switch is not as reliable as the click on / click off type. Also in regard to brightness, this flash light starts out about where this new flashlight and the Eveready flashlight I modified last time end up after running 3x longer (about 6x for the Eveready). Last of all, I like flashlights that run longer than 52 hours. So for a cost of about double that of the 52 hour flashlight and 10 minutes of my time I ended up with a much brighter flashlight, over 3 times the run time, a reliable switch and in floats.
It says “Runs 10x Longer” on the packaging. 10x longer than what? My first long run time modification used a Rayovac flashlight that looks almost exactly like this one but it had an incandescent bulb in it (gets hot, wastes power). Unmodified, it had a 4.5 hour run time.
Here is the instructable for that modification:
Here is a link to the 360 hour modification.
About this flashlight (before modification):
45 Hour run time (ANSI FL 1 Standard)
Rayovac model EFL6V10LED-B.
Lifetime Warranty (which I wasted no time voiding)
I got mine for $5.48 plus tax. It is a great little flashlight. If you don’t have an emergency flashlight you might want to buy this one even if you are not going to modify it. And then go the extra mile and buy an alkaline battery as a spare (150+ hours run time between the two). This flashlight in not up on the Rayovac website so here it is on the Walmart web site:
So why am I doing another Instructable modifying a flashlight to make it run longer on a set of batteries? I still can’t find a good readily available flashlight that will run a couple of hundred hours on alkaline batteries for about $5.00,
So the first thing you will want to do is install the battery and play with, I mean test your flashlight. If you are having second thoughts about modifying it (you will give up some brightness) perhaps you should by a second one. I did.
Next unscrew the front of the flashlight. The first picture in this step shows this assembly unmodified. Next void the warranty by making the cut in the metal strip as shown in the second picture. I used diagonal cutters. You can also use a dremel tool (rotary warranty voider).
This flashlight has a higher current drain than the other two flashlights I modified so it requires a 1/2 watt or higher resistor. I used two 1/4 watt resistors in parallel (two 50 ohm resistors in parallel = 25 ohms) to get the needed 25 ohms at 1/2 watt. I already had these resistors. If I needed to buy a resistor I would have bought a 1/2 watt or 1 watt 25 ohm resistor.
Solder the resistor(s) as shown in the third picture.Reassemble you flashlight and you are ready to "test".