Why do 18650's have flush anode's?

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Doug

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Why do 18650's have flush anode's, when every other battery has an anode that protrudes?

I have an EagleTac, and a PD31 that can not use the AW 18650's I have because (I assume) they are not making contact. Should I even try those little neodymium magnets that you can attach to the anode to provide a protrusion, or just send them back, and get 18650's with anodes that protrude?

If I get different 18650's, which ones should I get?

Also, is the only real benefit to 18650's, that they provide a little more run time?

And if anyone has extras of those magnets, and want to send me at least 2 (preferably 4), please PM me ;)

Thanks!
 
Doug said:
Why do 18650's have flush anode's, when every other battery has an anode that protrudes?
Click to expand...
Because they are industrial batteries that are intended to have nickel strips welded to the ends and joined into packs. They are not consumer batteries intended to go in flashlights.

If you have a light designed to accept 18650 cells, then the light should be designed to accept flat ended cells since this is the standard configuration for those cells. I'm not saying all lights necessarily meet this requirement in practice, because some lights simply have poor design. That's how it goes.
 
It further occurred to me that putting buttons on cell tops allows the light to include a degree of reverse polarity protection, which can save you from blowing up your LED driver if you happen to put the battery in the wrong way round. But now of course you have to buy specially made 18650 cells rather than being able to use just any cell. Life is full of compromises...
 
Protected cells will protect themselves from most damage, however I believe Mr Happy was talking about damage to the light itself from a cell inserted the wrong way.
 
When I purchased an Eagletac M3C4 two months ago, I was aware that my AW cells wouldn't work with this light for the reasons you state. I purchased a pair of Jetbeam 18650 2300 mAh button-top (ie. exposed anode) cells at LightJunction and they work fine. I suppose you can try magnets but that may result in an overall length that is too long for your light.
 
Because it is the STANDARD form factor for 18650 !

A raised anode is added for the small flashlight market and sometimes not in order to add a protection circuit without exceeding the max length.
 
Get a beefy soldering iron, (regulated preferred very much over non, though one of the "hammerhead" tips that RCers like to use should work). Put a dab of flux on top the cell and tin the iron well (good blob of solder on the tip) and hold it to the top of the cell till the solder 'wets' the positive terminal(starts sticking to it, flowing out on it slightly) , then remove the iron. I have 2 AW2900 18650's that I did this with and got a solder bump on the positive end ~4mm diameter and 1/2mm tall. This lets the cells work with my nitecore IFE2 which was made to take 18650s, but required button top ones. I'm not normally one to suggest soldering to Li-Ion batteries, but with my iron dialed up to 800F, I could do this in < 3 seconds. If you cant do it in < 5 seconds then you need more power to do it without risking damage to the battery.
 
Doug said:
Why do 18650's have flush anode's, when every other battery has an anode that protrudes?

I have an EagleTac, and a PD31 that can not use the AW 18650's I have because (I assume) they are not making contact.

Doug, I have the Fenix PD31 and the AW 18650 2900 flat tops DOES work with this light.
Are you sure the light works? try a different cell to make sure.

gea
Click to expand...
 
Sure enough! It worked.... Appears 1 of those 18650's is no good! When I put it in the charger it just shows charged, if the protection circuit was engaged, putting it In the charger should reset it, right? Now to find the other two 18650's and see if either of them work.... One advantage to single sell lights is, all you need it 1 working battery!

gea said:
Doug said:
Why do 18650's have flush anode's, when every other battery has an anode that protrudes?

I have an EagleTac, and a PD31 that can not use the AW 18650's I have because (I assume) they are not making contact.

Doug, I have the Fenix PD31 and the AW 18650 2900 flat tops DOES work with this light.
Are you sure the light works? try a different cell to make sure.

gea
Click to expand...
Click to expand...
 
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