I was just wondering, how do you protect your collection from damages such as leaking batteries. My cousin suggested me to buy some DEHUMIDIFIER in order for the moisture inside my display cabinet to be eliminated in order for my collections not to be damaged.
The only way to provent leaking batteries is to replace them before it happens, or dont leve them in the toy for long periods of time. No matter what we do, time will take its toll on these, just like every vintage toy you see. Its just the way toys go unfortunately. Some will look better than others, but I dont think its possible to keep something 100% perfect forever. So I just enjoy their perfection now while it lasts 
avoid letting too much light on on them.Sunlight especially can really take its toll on toys. This applies more to boxes but colors can fade on anything over enough time I have room darkening curtains in my room. Honestly the best way to keep things looking like new is to put them in storage and not display them at all. But that’s no fun.
The batty thing is a good idea, but I wouldn’t bother with a dehumidifier unless you live in a really wet environment.
having a dark curtain on your room during day is a big help to prevent fading of the color of the toy, btw having a DEHUMIDIFIER in my display cabinet is essential for me coz I live in a tropical country where it is always rainy and the air is humid. My DEHUMIDIFIER collects around 100ml of water every 2 weeks. Lol.
Museums use UV resistant glass. You can buy display cases like that (which would probably have to be custom), but it’d probably cost more than the item you’re displaying. Just keeping it out of direct sunlight in a dry environment is probably best. Swithing to lithium batteries would ensure no battery acid leaking occurs, in case you really forgot to take out your alkaline batteries.