Old people hate tail switches. They want to use the normal grip with a side switch.
Don’t underestimate the importance of a battery indicator to them, either. They’re not clicking 3 times to get the voltage numbers flashed out…that is too complicated. A simple 4-dot indicator would be ideal.
Grandma light should be KISS. (Keep it simple and stupid)
Side switch/selector ring. 3 modes top. Warm flood light.
Be able to tail stand, tube preventing from rolling.
Tough build, like Solarforce L2P for example. Perfect light.
Mike
I don’t have any flashlights that require two hands to use. There’s no way I would give any old person, or any person, a light that requires two hands to turn on or off. I don’t think you’re going to be able to make a magnetic ring that’s easy for an old person to use with one hand. So don’t do that. With a tail switch it can be operated with one hand or two if they wanted to. You can always find the switch. If you wanted to have a magnetic ring for changing modes I guess that’s not too bad. Requiring two hands to turn it on and off is a no-go. I think sticking with a type-c port is best but a larger simple rubber flap/cover. So either one of your pictures I think would work for old people. Ring at the front or back doesn’t matter. Or even better another switch at the front to just press and change modes with one hand.
Sounds like I'll be Forever Young™, then, because I only like tail switches. 
Regarding a "Grandma" light, I don't have any skin in the game.
My mom is 80 years old (and a great grandma), but she can handle regular flashlights just fine.
In fact, everyone in my immediate family does just fine with regular flashlights.
Good luck with the Grandma light, though. 
I vote A and will probably be getting one for my mother. She and I prefer her to have a tail light switch, she only uses the flashlight when she walks the dog and will accidentally turn off the light numerous times with a side switch.
A lot of old people just want to be able to turn something on, have it stay on, and sometimes make it brighter.
Currently she has a Fenix PD35 but I want something with built in charging for her.
I much prefer them to side switches, so it sounds like I’ll grow old very gracefully!
My mom could never deal with a tail switch, though. She needs the most basic light ever. The cheap, orange 2 D-cell drug store flashlight is what she grew up with and used through most of her life, and she hates change. I got her a M21E (FC40 4000-4500K) recently, and it’s pretty good for what she’s accustomed to.
Ring at front, no tail switch.
I think the ring is a nifty idea. But definitely on the head end. A side button works well. One thing, the ring (or button) should have a true off position that breaks the power circuit. For a button, a forward clicky would be ideal.
Many times this kind of light might sit unused for long periods. It wouldn’t be good if the parasitic drain had killed it just sitting there. As it would likely be using any kind of pure “E” switch design.
Yes, built in charging would be mandatory for this kind of light. With some kind of charge level indicator at turn on.
Compact light. 18650. Two to three levels. No memory, always start on low. Designed for efficiency and runtime. No battery draining “turbo”(that also can be dangerous).
Yes, KISS!
I know the realities of design and production will influence the final configuration. No way to give everyone what they want, but the above are my thoughts.
It’s actually a reminder ‘motto’ for industrial designers and engineers, when they exaggerate in complexity and added features.
“Keep it simple, stupid.” calling the engineer stupid because they overcomplicate things.
It doesn’t mean keep the design stupid, because stupid designs are stupid.4
For the rest i agree with a side switch and 1 mode, 150 lumen or so.
My mom is old and i gave her a 1 mode CR123A light 5 years or so ago, which she carries in her purse / bag.
It always works but she only uses it like 4 times a year.
The tail switch is a bit finicky for her, though.
2× CR123A in parallel, next to eachother would be better, grips like a remote control, can’t roll off the table, should last a long time.
It’s not as easy to produce though.
A tube is easier for battery access.
I second this. We need more lights with the mag rings. The ring must be controllable independent of the tailswitch. Tailswitch for quick tactical use and convenience. The WK40 for instance, an on/off at the ring would be a huge improvement IMO.
The WK40 is already a great starter design, and there’s the… forgot the model, but the DLsomething dive-light that has the magring switch around the head.
Stick a charging port on the “dive light” (only don’t call it a “dive light” anymore!) like the WK40 has, but unlike the WK40, don’t include a separate tailswitch, but make it off/low/high or maybe off/low/medium/high like the dive-light.
4500K should be a nice balance between warm and “yellow”. People with cataracts don’t like overly blue light, as it glares too much.
I’d even go to 26650, as the wider diameter would be easier to hold.
LuxPro has some lights that have a thin rubber sleeve on the battery-tube, and such a sleeve can be textured with bumps or ridges, and just be rubber for better grip, especially when wet.
As for the magring, MAKE IT BIG. Garishly big, like a cheap costume jewelry bangle-bracelet. Ideally a contrasting color like blaze orange, too, so gramma knows what to grab for to turn it on. A plastic or rubber slip-on grip that goes on the ring would work just as well if not better than a freakishly large ring itself.
Also, an easy way (that’s impossible to ignore) to tell when the battery’s getting low. Eg, a quick blip every 10sec when voltage drops below 3.6V, a pair of blips every 5sec when it drops below 3.3V, and a blip every 2sec when critically low like 3.0V or less (ie, mere minutes of runtime left). Gramma’s not going to pay attention to even a blinking red LED on the side of the light, but won’t be able to ignore the light blipping out every few seconds. “Annoying? Well, yeah, then charge it!” 
If you really want to make it gramma light, a movement sensor that will automatically turn off the light after, say, 2min-5min of no movement. So if gramma puts down the light and wanders off to answer the phone or whatever, the light won’t be dead next time gramma grabs for it.
And if not too high-strung as far as output (and heat), it can even be made lighter and grippier by using nylon (like some Nextorch lights) instead of Al. Probably better impact resistance if dropped, plus lighter, and can be made in any color vs having to anodise Al after the fact.
(Goggled it: DL30 has the magring.)
Interesting idea the auto off. But then couldn’t use it longer term for ceiling/wall bounce for room/area lighting. Also, maybe a problem for the bathroom where maybe both hands need to be available longer term. Unless if it can be disabled ??(too much complexity). It would be a no go for “my” grandma (or even me).
You’re probably aware that pet food marketing is tailored to appeal to the owners’ potential likes, and not their pets. :laughing:
Same thing occurred with the proposed “Simplified Anduril” fork where the number of “must have” suggestions basically rendered it little different from the full fat Anduril.
A rotary switch is more intuitive than a single-button mode switch, but it won’t appeal to Grandmas with arthritic hands, who already have enough trouble opening pill bottles.
An additional button on the end? More unnecessary complication, except for the select group of Tactical Grandmas who served in special forces.
As noted, the ideal Grandma light has already been produced. A drop-resistant, single- or two-mode (at most) light with a slide switch with three discrete steps also discernible by physical position, clearly labeled “Off/Low/High”.
No more, can be less.
You mean like the DL10R? Magnetic selector ring off/low/med/high and USB-C charging.
Just adding a couple of cents to the commentary…
TIR would be simpler for manufacture, I would think, and more robust over the long haul. A colour temp around 4000 - 4500 K would be ideal.
If a magnetic switch is a good idea (and it is), what about a sliding mag switch on the side of the body, rather than a ring at the front? This would mean that the light wouldn’t roll anywhere too fast if it was placed on a sloped surface, and the slider could be nice, wide and simple to move with an arthritic thumb.
Either just an on/off slide, or maybe an off/low/high that has three hundred or so lumens on high. It would last ages on a 26650.
Someone above also suggested non-metallic body material. A great idea as it’s probably less expensive to produce. And it can come in wonderfully garish colours that might appeal to the ‘need to find it easily in dim light’ circumstance that would apply to the back of any kitchen drawer. Any plastic material would have colour all the way through too, so less obvious bumps and bashes to disturb the surface colour compared to anodized Aluminum.
Plastic is also lighter, so less chance of smashed toes if the light gets dropped.
4Sevens/Prometheus has an awesome ‘standby’ light that has magnetic charging through the tailcap and keeps the light topped up all the time, plus a nice fancy mode that turns it on in moonlight mode if the power fails. This would be absolutely awesome if it could be made at a significant price reduction over the monster that 4Sevens makes (although that light is definitely on my radar).
But then i.m.h.o. a diving light with a thumb operated slider would be even better regarding geriatric ergonomics.
And in stead of dimming or mode switching you could use a reed relay (magnetic switch) in stead of a Hall sensor and electronics slowly draining the battery.
A ring seems a bit difficult to twist with the thumb and index finger of an old arthritic hand, if one hand operation of the light is the goal, which should be the goal if the elderly person depends on a cane or a banister to stay upright.
I can see many scenarios where this feature could go horribly wrong. A flashlight turning off by itself when you are experiencing a power outage is not ideal, especially for the elderly or otherwise limited mobility folks.
Just off the top of my head: the power goes out. At some point, Gramma takes the flashlight into the kitchen and sets it down someplace to make some food. 2-5 minutes later, it goes off by itself. Now you have an old lady across the kitchen in complete darkness, unsure of exactly where her light is, and unable to see anything. That’s a bad scenario. It could result in a fall or other injury.
If gramma’s going to be using A Gramma Light in the middle of a blackout, that she needs it for ceiling bounce in the kitchen, or to hit the can, I think she’s got bigger issues than the light’s auto-off feature.
We’re talking about A Gramma Light for everyday use, NOT to stick into gramma’s bugout bag or for SHTF situations.
She could buy Ye Olde Brooklyn Lantern or whatever they were called, for blackouts.
Or maybe someone spring for an LT1 or something for her.
Frankly, I was picturing something like a DV-S9 with the magslider, which’d otherwise be an ideal Gramma Light, but it’s got a 10mA parasitic drain and empties a 26650 in like 3wks.
But I’ve said ages ago that an easy-to-slide slider would be ideal, with gentle stops/detentes to select 0/L/H or 0/L/M/H, ’though the initial query was where to put a magring, whether front or tail, so I stuck with that.
Unno, maybe. Ain’t got.