Thought this might be of interest - and a bit of a warning.
I used my spare headtorch batteries to power the xyl’s camera and just purchased a pack of four Duracell AA to replace them. These were thrown into the lid pocket of my pack but not inside one of the drybags and, during an abortive attempt on an Arran summit, they got rather wet and the packaging proved to be conductive!!
The packet shows burned rings above the positive terminal on each cell and the batteries are flat. Good job everything was so wet, the potential for a fire was rather evident. Next time, carry the spares inside one of the dry bags!!
Ouch! Guess they were in the cardboard packaging that’s popular for batteries these days. I’d better check my geocaching bag. I wonder how damp the cardboard needs to get before it starts conducting…
I’ve found that the plastic gloves that are supplied at
garages are quite useful for carrying spare sets of AA cells.
Just drop the batteries into the fingers, a quick twist at the
base of the fingers, wrap them in the hand part, and put a rubber
band around them
I agree, I’ve been trying to reproduce the effect all evening and with our soft tap water I can’t get the resistance below 200 kohms per cm. I have in the past measured the pH of some peat samples at about 1.5, so blame the peat!
No peat was involved, my pack lid may not be waterproof (whose is?) but I didn’t swim in the stuff.
I still have the battery packaging somewhere so will test the bulk resistance when wet. My money is on the ink containing metallic elements. I normally keep everything in dry bags, just was too lazy to do the job properly I guess.
Incidentally two cells totally flat, two cells at about 25% remaining capacity.
I’d have thought that for cardboard to scorch, its temperature would have to be well above 100° Celcius - and it could not then still be wet.
Are you sure that the rings are not caused by electrolysis of some sort? (That the marks are only over the +ve terminals could be a clue here.) This could happen at a much lower current and over an extended period of time.
I carry several rechargeable batteries in my pack and used to worry about this issue (particularly the 18650 spares for my torch that can provide enough current to cause a fire). I now have all of them (AA, AAA, 18650) in plastic cases.
The cases can be had for next to nothing if you look around and often are found on Ebay or Amazon in multiples of 4 or 8 and in various colours and various sizes for different batteries.
