DBSAR, what kind of conclusions have you made about this temperature related issue on the T1?
In our own tests it seems most of the battery tubes never exceeded 60°C and the batteries themself seemed to range from 50°C to 56°C. (I haven’t had time to sort through all the posts)
You reported 67°C in your battery tube, right? Do you think your T1 was an anomaly or maybe we should test these lights in a hotter environment?
I looked at a few battery data sheets to see what kind of temperature related info I could find. It seems there is a regulation Per UL1642 that says cells have to withstand 130°C without exploding or burning. Edit: I see that the Panny B has an 80°C limit.
An operating range of up to 60°C surface temp seems to be the norm for most cells.
Do you think this means the T1 was built within the safety specs and your T1 had an issue? Even as hot as your battery tube got, your battery should not have been anywhere close to its danger limit.
3.12 Operating Temperature (Cell Surface Temperature) Charge: 0 to 45°C - Discharge: –10 to 60°C
9.4 Heating Test
Test method: To heat the standard charged cell at heating rate of 5°C per minute up to 130°C and keep the cell in oven for 10 minutes. Criteria: No fire, and no explosion.
2.6 Allowable Environment Temperature Charge 0～+60℃ -
2.8.2 Discharge Conditions
Discharge at cell surface temperature below 80℃.
I couldn’t see a max heating test.
2.9 Operating Temperature Charge 0 ~ 45℃ Discharge –20 ~ 60℃
4.5.4 Heating Test
Cells are charged per 4.1.1 and heated in a circulating air oven at a rate of 5ºC per minute to 130ºC. At 130ºC, oven is to remain for 10 minutes before test is discontinued (Per UL1642).
Specification: No explode, No fire
3.11 Operating temperature (surface temperature) Charge : 0 to 50℃ (recommended recharge release < 45℃) Discharge: –20 to 75℃
9.4 Heating test
Test method: To heat up the standard charged cell at heating rate 5℃ per minute up to 130℃ and keep the cell in oven for 10 minutes. Criteria: No fire, and no explosion.
Sanyo/Panasonic 3400B and 3500GA
5.12 Operating Temperature
Charge 0 ~ +40℃
Discharge –20 ~ +60℃
(2) High Temperature
“Do not use or place the battery near fire, a heater or a high temperatures (more than 80℃).”
The battery’s polyolefin separator may get damaged from the heat and could cause an internal short circuit. This may cause the battery to catch on fire, smoke, explode, or
cause heat generation.