Battery confusion: Is the Devterm specifically designed for unprotected cells?

Hi there,

So In purchasing a set of protected batteries, I noted that it does fit inside the DevTerm, however because the battery diameter is slightly larger than what the cover supports, the battery door does close, but causes the entire back case to slightly bow, meaning the shell starts to separate from the front housing on the top of the unit (the plastic tab no longer catches the faceplate).

So my question is, was the DevTerm specifically designed for unprotected batteries, which mostly fit inside the DevTerm fine without pushing the size limit of the battery compartment? Or is using such batteries unstafe (even if being left in the device all the time - On/off/charging)?

Take a look at the product page on the main site:

It can work without battery protection, but based on that wording it would seem they still recommend it.

There are a variety of 18650s that have built-in protection that will fit. You just have to shop very carefully to get the right size.

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Just for an example, I’m using Samsung 35E 18650 3500mAh 8A - Protected batteries. They fit without any bowing/deformation of the chassis. They are very snug, but have showed no problems in 4 days of semi-frequent use (2-4 hours per day). They have been charged once per day.

Thanks. It would be nice if we had a sticky containing a definitive list of batteries (confirmed by users) which list if:

  • There are no issues.
  • Barely fits, but requires pry tool to remove batteries.
  • Fits, but diameter causes case/battery cover issues.

Or at least some resource which isn’t scattered across multiple threads. For my contribution I’ll say:

NCR18650B (Panasonic NCR18650B Button Top Battery — FlashlightWorld) = Very tight (requires pry tool), battery cover can be forced close, but will cause case bowing.

Not a sticky, but there’s this great thread:

For what it’s worth, I’m using 2 Nitecore 3.7V 3200mAh cells in mine and they fit perfectly.

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