D-cells are fragile

[Hellbore]

I was doing some drop-tests for durability on some lights, in particular a 3D Maglite and a 2D Husky 4W tactical LED light from Home Depot.

I noticed that if the flashlight is dropped and lands a couple times on the tailcap or front bezel, both Duracell and Energizer alkalines will become damaged to the point where they have contact issues and cause flickering when the light is shaken. After some light whacks, the Energizer cell was damaged to the point where it would only supply a max of 100mA.

What seems to happen is the + contact of the battery gets smashed in very easily by the forces of inertia, the cells are so heavy that when the light is moving fast and abruptly stops moving, the force of the battery against the battery in front of it, or against the flashlight's + terminal, smashes in the + end of the battery. The - end also gets dented in, especially on the batteries not touching the tailcap spring.

Has anyone else noticed this? This seems pretty bad, I have always considered D cell lights to be tough but this recent testing seems to prove otherwise.

I can cause the damage even just by hitting the tailcap of the light against the palm of my hand a few times. A few good whacks is enough to ruin the average D cell.

Knowing this makes me not trust D cell flashlight so much for rough situations.

 

[Mr Happy]

Maglites have a rubber cushion and a contact spring at the bulb end of the battery compartment, and have a big beefy spring at the tail cap end. Given that, there is perhaps a limit to what more can be done to protect the batteries against shock.

I'm a little surprised to hear alkaline cells are so fragile, since as far as I know they do not have a brittle carbon rod in the center but have a metal rod instead.

In my own case I prefer to re-fit 2D lights with 6 rechargeable AA cells in adapters. NiMH cells have their own fragility concerns, however...

 

[Hellbore]

Where is this rubber cushion? I'm looking at my 3D Maglite right now and I don't see one.

 

[Mr Happy]

Maybe I'm mistaken. Perhaps it's just plastic.

 

[cheetokhan]

I've seen this happen many times over the years in my C and D cell lights. My 4D Mag and my 3C Pelican SuperSabreLite have so much spring pressure cramming the cells together that the batteries get crushed over time regardless of how careful I am.

 

[SilverFox]

Hello Hellbore,

Been there, done that...

It's even worse when you load up some NiMh D cells in and end up with smashed in cells...

Tom

 

[mrk442]

I've seen this happen many times over the years in my C and D cell lights. My 4D Mag and my 3C Pelican SuperSabreLite have so much spring pressure cramming the cells together that the batteries get crushed over time regardless of how careful I am.

Hum I wonder if a softer spring would help at all.. I actually tend to run a shorter softer spring "with braid jumper" on both sides when ever possible but i have never had the guts or $$$ to try a drop test on one of my mags. It might not really help though since there is a lot of mass involved with those D-cells and it sounds like they just are not up to the task of withstanding it.

 

[LukeA]

Put washers between the cells. Transfer energy to the sides of the can which are much better able to handle the loads in this end-drop scenario.

The washer height isn't critical, they could just prevent the button from compressing into the electrolyte, or they could be the positive contact for the cell. Then you'd have to get a shorter spring and you might want to do something about the washers' poor conductivity, like electroplate them with copper.

 

[Hellbore]

Put washers between the cells. Transfer energy to the sides of the can which are much better able to handle the loads in this end-drop scenario.

The washer height isn't critical, they could just prevent the button from compressing into the electrolyte, or they could be the positive contact for the cell. Then you'd have to get a shorter spring and you might want to do something about the washers' poor conductivity, like electroplate them with copper.

This seems like a good idea, I think I will try it.

Might be possible to get some copper washers, if not, I am pretty sure I can get brass or stainless steel washers.

 

[Mr Happy]

That's sort of what I was thinking about with a Maglite. If you take the switch/bulb assembly out of the body, you find that the front cell is supported by its "shoulders" on a plastic support, rather than pressing on the battery button itself. For good shock resistance, it is required that each intermediate cell is supported on its shoulders as well. To do this requires some kind of insert between each cell.

Note that this is only likely to work well for real alkaline cells which have wide metal tops. For rechargeable cells and adapters that have plastic tops and small metal buttons it is more difficult to provide cushioning and electrical contact at the same time.

 

[Lane]

I noticed that if the flashlight is dropped and lands a couple times on the tailcap or front bezel, both Duracell and Energizer alkalines will become damaged to the point where they have contact issues and cause flickering when the light is shaken. After some light whacks, the Energizer cell was damaged to the point where it would only supply a max of 100mA.

What seems to happen is the + contact of the battery gets smashed in very easily by the forces of inertia, the cells are so heavy that when the light is moving fast and abruptly stops moving, the force of the battery against the battery in front of it, or against the flashlight's + terminal, smashes in the + end of the battery. The - end also gets dented in, especially on the batteries not touching the tailcap spring.

Has anyone else noticed this? This seems pretty bad, I have always considered D cell lights to be tough but this recent testing seems to prove otherwise.

It happened to me this weekend. My Mag 2D fell off a trailer I was hauling into the road way at 45MPH. Other than some bad road rash the light worked but was dim. When I checked the batteries I noticed the same thing you mentioned above. Put in some new batteries and it works well!

 

[Hellbore]

Well I'm glad I'm not the only one who sees this as a problem

I'm sure the collective brains of CPF can come up with a solution to this problem!

So far washers have been suggested, should we start testing there? I will as soon as I get a chance to get some!

 

[LukeA]

Well I'm glad I'm not the only one who sees this as a problem

I'm sure the collective brains of CPF can come up with a solution to this problem!

So far washers have been suggested, should we start testing there? I will as soon as I get a chance to get some!

I read a button height of 0.110in. on a Rayovac D alkaline.

 

[Black Rose]

I'm sure the collective brains of CPF can come up with a solution to this problem!

My solution would be to not drop the light

 

[Hellbore]

My solution would be to not drop the light

But I'm clumsy!

How do you think I got so interested in LED lights in the first place? Do you have ANY idea how many Xenon Maglite bulbs I burned out before I discovered LED's ?

Those poor Xenon bulbs died in great numbers. Either I dropped the light (usually while working on cars), or the light rolled off a table or other flat surface and fell to the ground, OR I attempted to tail-stand the maglite while working, and of course it fell over!

Hey, that gives me an idea, someone needs to make a Husky-style tailcap for the Maglite with little feet, it would prevent the dreaded maglite-rolls-away-while-working, AND the dreaded maglite-can't-tailstand-why-did-you-think-it-could?

 

[Mr Happy]

Those poor Xenon bulbs died in great numbers. Either I dropped the light (usually while working on cars), or the light rolled off a table or other flat surface and fell to the ground, OR I attempted to tail-stand the maglite while working, and of course it fell over!

Hey, that gives me an idea, someone needs to make a Husky-style tailcap for the Maglite with little feet, it would prevent the dreaded maglite-rolls-away-while-working, AND the dreaded maglite-can't-tailstand-why-did-you-think-it-could?

Ah, then I recommend one of these:
http://www.rayovac.com/flashlight/ind2d-b.shtml
or these: http://www.rayovac.com/flashlight/isl2d-b.shtml

Especially if you do as I do and upgrade them to 6 NiMH AA cells plus 6 D bulb.

They are light, have soft rubber end parts for drop cushioning, they stay put without rolling, they can stand on their end without falling over, and they can be hung from a hook.

 

[Black Rose]

But I'm clumsy!

How do you think I got so interested in LED lights in the first place? Do you have ANY idea how many Xenon Maglite bulbs I burned out before I discovered LED's ?

I only have 2 flashlights that take D cells. One is a rubberized plastic body Garrity 2D and the other is a 37+ year old Ash Flash 2D.

The Garrity used to be one of our camping flashlights, but now stands guard at our back door. I think that one might have been dropped on the ground but never on hard surfaces. There is nothing inside to protect the cells other than a big tail spring.

 

[Turbo DV8]

But I'm clumsy! Either I dropped the light (usually while working on cars), or the light rolled off a table or other flat surface and fell to the ground, OR I attempted to tail-stand the maglite while working, and of course it fell over!

Sounds like you are a perfect candidate to graduate to a head lamp... as long as you don't have a tendency to bang your head against the wall!

 

[Hellbore]

Sounds like you are a perfect candidate to graduate to a head lamp... as long as you don't have a tendency to bang your head against the wall!

Yeah, what I want is a Zebralight but I can't afford it right now. Maybe for Christmas? :rock:

 

[chewy78]

My solution would be to not drop the light

good point