Phone charger/Cigarette lighter compatible?

I am about to hit the road (mid June) to catch the end of Power Tour and see the corvette museum in Kentucky and need to be able to charge my iphone. I have a 1970 Belvedere. Is it safe to charge an phone in these old lighters? I think I've read that it isn't. If not, what can I install to use?

I've tried to use a GPS charger in my '70 RR. It should work, but it is intermittent (loses the connection sometimes). Remember, "back in the day" the first plug-in chargers used the cigarette lighter hole. Newer cars (no cigarette lighter) seem to have slightly re-designed holes that might fit modern chargers better (and not a cigarette lighter). It's 12V straight from the battery, so go for it. For my car, I've at least considered wiring in another one.

I've had no issue with it. They're the same as newer cars, 12v. It may be intermittent due to age/wear, but just push it back in every so often. I've used mine to charge my phone.

The lighter in my '64 Belvedere works fine, but it doesn't work with a phone charger. I haven't tried my '66 Satellite lighter with a phone charger yet.