[dead of night]

Hi. I have a lot of portable radios and CD players. Many of them I will not use for at least a year. Is it safe to leave the batteries in, or should I take them out?

 

[nfsu]

Battery left in portable stuff for a long time can corrode or even leak and damage device. It is just safer to take batteries out.

 

[sgrossklass]

Generally, alkalines are much less prone to leakage than cheapo carbon zinc cells (which are junk anyway). Their leakage probability seems to increase with discharging - I've had to clean up some leakage from empty and long overdue (date code wise) Energizer cells in my first camera that sat unused for close to 10 years, while with an ICF-7600A (that looked like it had spent a number of years on a dusty attic, face up) I got some age old Sony branded alkalines (Made in W. Germany, these can't be much younger than 1989/1990 and were presumably bought together with the rx which was discontinued in 1988) that still had around 1.4 V left and did not show any leakage (they're now being kept in my "battery museum"), while the foam on the battery compartment door didn't fare quite as well... Recharging attempts also tend to cause leakage.

I'd say if the alkalines used are close to full and there's no battery drain in off mode (e.g. with devices that have a "hard" power on/off switch), one could leave the batteries in. Otherwise better remove them and possibly store them in the fridge.

 

[Copperjacket]

In my experience batteries always leak in the equipment you most want to keep in good condition so I would pull them out. Better safe than sorry.