Head/Tail Spring Compression Question?

[Remembertheslap]

A longish cell (protected button top) appears to be close to maxing out the spring compression (Keeppower 18650/Acebeam TK18).

A flat top, unprotected, is maybe 3-4 mm shorter. Spring contact is fine.

Didn't come with the Acebeam cell.

There's a theory with magazines, that you shouldn't store them fully loaded, because the springs are under max compression all the time and can weaken.

Any thoughts on this? Cheers, greetings from Ireland.

 

[knucklegary]

Hi Ireland

Same applies to flashlight loaded batteries too tight. Overly tight spring pressure will over time "set" springs

Imo proprietary batteries suck, I hate them

Tk18 has low battery indicator, Yes? Flickering light.. Then I'd definitely go with a good quality non protected cell just make sure to keep track of low voltage even with low battery warning, I don't trust UI to always work

Yep, give those springs a break!

Talking about Breaks have you ever seen the surf at Mullaghmore Head? Cold water huge waves😎

 

[Remembertheslap]

Thanks for the reply.

Yes "take a set" is the phrase I was looking for! I bought the protected button tops from Nkon.eu as 'recommended for this light'. Just ordered some Sony VTC6 - can use the button tops in other cheaper lights...ever seen spring set happen?

Never been to Mullaghmore but I'm on the west coast, waves can be fierce at times!

 

[Duster1671]

What is the explanation, from a materials science perspective, for a spring taking a "set" when it's compressed to a stress lower than its yield point for an extended amount of time? Creep?

I have a hard time believing this would be a real problem for a properly-designed spring, especially one that spends most of its time at room temperature.

Has a loss of compression in magazine springs due to creep ever actually been documented, or is this just another myth that has been passed around until people started to believe it's true?

 

[knucklegary]

I am not an expert just by my own experience, I've seen 223 clip springs set, not cheap imported magazines but older US Colt mfgr.. Conditions could contribute to the issue, sub 0 degrees.. tropical climates idk

Maybe I'm mixing apples and oranges, but gas engine valve springs lose spring pressure and become set, that's very common.. and auto/truck front end coils are notorious for becoming set

I see no reason why to expect light duty flashlight Cu springs would Not become set being over loaded?

Also, too pressure on soft li-lion anodes, not to mention body tube threads, cause issues as well

But then again it could all be old wives tales

 

[bykfixer]

You can always stretch the spring if it becomes compressed enough to not provide a firm grip/contact with flat top cells.

 

[knucklegary]

I think tugging on them for better contact is way better smashing them down 👍

 

[Duster1671]

knucklegary - Overloading a spring or cycling it beyond its fatigue limit could certainly be problematic. The latter is unlikely to happen in a flashlight, but the former could happen with a battery that's too long.