Is it safe to charge my ipad in my car?

I bought one of those things that go into what used to be the cigarette lighter of my car and into which you can plug a USB cable. I tried using it to charge my ipad, and I keep hearing a beep, something that doesn't happen when I charge it at home. What does that mean?

Alex2014-06-28T12:30:06Z

It should be fine I've never had a problem with that before.

William2014-06-28T12:27:55Z

Do you live in a hot country? It could be because of the heat.