Problem is that
1. It is an unprotected battery and
2. It is an inr battery not lithium ion
Why does nobody have an answer to this..its really bothering me. Could running a battery too hard cause it to short circuit internally and read no volts?
INR batteries are lithium-ion.
Along with ICR, IMR, NCA, LiPo, etc., all are lithium-ion. They all just use different methods of construction or variations on the lithium-ion chemistry (that determine their degree of safety when vaping).
INR aren't quite as safe as IMR batteries, but they are safer than ICR/LiPo's. Samsung 25R's are INR but pretty well everyone trusts them.
I've been testing batteries for over 20 years and have never seen one go to zero volts when stressed unless it vented badly or burst. And I have severely stressed and destructively tested many, many of them. A battery, even if shorted out for several minutes, will rebound back up to some voltage above zero volts once the short is removed. There are unlikely, but possible, scenarios though for a zero volt battery.
- A low quality battery could "fuse" itself by melting part of its internal connections.
- A low quality battery with a CID (current interrupting device) or PTC (positive temperature coefficient, i.e., temperature protection) device inside, as part of the cell's construction, could fail to return to normal after one of these protection devices were tripped.
- There are counterfeits of rewrapped batteries that use a very tiny battery inside with wire leads soldered to the battery top and case (negative). The rest of the space inside the 18650 case is filled with sand so the weight is about right for an 18650. The battery looks and feels OK but the tiny gauge wiring inside can become unsoldered under heavy load.
No idea though why your cells are at zero volts though.