Two of my old headlamps that I haven't used in a couple years are completely ruined because of battery leakage. I have some rather expensive test and metering instruments and I am really concerned. Short of taking the batteries out, is there another solution? Do the modern rechargeable NiMH or lithium batteries have this potential problem?
Taking out the batteries is the only sure way if the instrument is going to be unused for a while. My experience so far is that standard alkaline batteries leak E... & D... Both companies have replaced several expensive flashlights. It does require some patience for the return process. They always honoured their product. The batteries cannot be mixed, by brand or date.
The only alkaline battery that I used that never leaked was Varta. I cannot get them locally anymore & they cost more.
I have not had a lithium battery or a rechargeable MiMH to leak, any brand.
One thing that will cause a leak is to drop the battery on a hard surface, like waist level onto a hard wood floor, in or out of the device. If I do drop one like that I set it aside in a container for at least three days & watch it. If it does not leak I will use it.