iPhone 12 wall charger and cable

That's incorrect. It's all forward and backwards compatible, although the speed might be an issue. There's nothing that will damage an iPhone by using a lower power source. Obviously a 5W cube provides 1/4 the maximum power as the 20W that the newer iPhones max out with when using a USB-C to Lightning cable. However, that won't damage a battery. I have no idea why anyone would say anything like that with no merit other than maybe trying to sell new accessories.

I still have an iPhone 7, but my family is using OEM and MFi USB-A to Lightning cables along with higher power USB-A power adapters and they've been doing just fine. If anything, they might be better for battery life, as slower charging inherently generates less heat. The benefit would be marginal though.

It's still effectively a single 3.7V nominal lithium-ion battery. Newer iPhones will take in 5V or 9V, and they end up converting it to a suitable charging voltage.

The sales person at AT&T is either mistaken, or simply trying to make a sale.

Apple encourages folks to utilize existing cables and charge cubes when possible.

I have found several Anker products to work quite well.

obgyndoc wrote:

Thanks for verifying a previous similar answer. Interestingly, I called another ATT store and they also said if you use the older USB to lightning, the battery will go 'dead'. It appears something is very wrong there and possibly, illegal. Have also checked some online articles, all of them confirming the safety, but longer charging times.

Thanks for all the help,

Gordon

I have no idea why they're saying that. My parents recently purchased a new iPhone SE (2020 edition) that comes with only a USB-C to Lightning cable. The person who sold it to them (at a Cricket affiliate) told them that it would be damaged if it wasn't charged with a USB-C power adapter.

The charging voltage of an iPhone maxes at about 4.3V. And all the charging circuitry inside an iPhone controls all the charging. All it needs is a steady DC power and it does all the rest.

You are welcome.

If you already have an existing Lightning charge cable and cube (used on iPhone 5 or newer), you could certainly use that. You could put the new Lightning - USB-C aside for future use.

Yes, those cables quite fine. Yes, the port in the car should also be fine.

You are quite welcome.

Thanks for that feedback. It is unfortunate that some retailers use fear to try and up sell a customer.