Can batteries be posted overseas

[AlizarinRed]

I have a beauty gadget to post abroad. Royal Mail says it can be sent but battery must be firmly packaged separately, which it is as the plastic packaging it arrived in (by mail, I am sending it on) holds the battery separately.
Should I put something on the front of the package to say battery is safely packed or should I not mention it so they don't open it to check. It is wrapped with a jumper and a book.
They'll ask at the post office if there are batteries in it. Should I explain or say no batteries?

Can't to send it without the battery and let the recipient buy their own battery.

Yes I could but I've already packed it - you're right that's the simplest answer.

Many countries scan incoming mail and if the contents don't match the customs declaration they may open it.

Plus if the battery isn't packed separately and the vibrator accidently switches itself on the postman carrying the parcel can get RSI. I think.

It is a safety issue (ie fire risk posed by lithium batteries). Ask at the Post Office, there is a special label to be attached to packages containing batteries. Whether or not the package is exempt will depend upon whether or not it is being sent by air and also, how the battery is packaged.

Royal Mail International post do not allow batteries, perfume is included too.
Royal Mail sent empty packaging back to me after confiscating a £75 bottle of perfume that was not allowed.
Check the website before posting!