I’ve played around with recharging alkalines. It works best when they are still at least half-full. I can put about 20% capacity back into them. However, they usually leak within a month or two, after charging. They’re definitely not designed for it.
Fun to experiment, but definitely expect them to leak if you do it. Also, there’s some risk of minor explosions during the charging process, although I’ve never had it happen. Keep the charging current low!
I’ve got an Alkaline/NiCad charger also. I’ve completely given up even trying to use it for alkaline batteries. As you say, to even try they should be at least half-full. The probability of leak after using it, especially if used when the battery is too discharged goes WAY up. If you have to mess with a NON-rechargeable battery that much, and incur that much risk….why bother?
My alkaline recharge success stories have generally happened with 1.2+V resting voltage cells. The brands I use generally leak only very little (if at all), no disasters here. The other day the thing pumped for 4 - 5 hours (130mA of current) on an old AAA cell and it came out at :THUMBS-UP: 1.57V. When charging alkalines, I put the charger upside down with a paper napkin under its cover, just in case. :-D
Cheers :-)
There used to be rechargeable alkalines available. I’m not sure if they still exist. They could only be recharged a couple of dozen times. Very limited usefulness, although they could be used where higher voltages were necessary. Though, NiZN is probably a better alternative.
Duracells are the worst name brand alkaleaks IMO. They almost always leak on me. Energizer is better - I have some 30 year old Energizers I saved that never leaked. However, I have seen them leak too. Rayovac is the best budget brand, rare leaks but it still happens.