Hello I own a 2015 Subaru Forester, and recently replaced the stereo Clarion unit by myself, with a second hand OEM unit, because the original died after a cross country trip. The radio was completely nonfunctional, the master screen would dim every time I turned up the headlights, and all front USB charging slots were dead. 

The new unit works fine. 

I hear rumors that the radio can be damaged like this if it is too hot outside, and also if you spend "too long" charging your phone using the USB. 

What workarounds do you guys use for this to protect the radio, and still be able to charge your phone inside your car? 

Am I just looking at upgrading the radio again when this new one dies? I purposefully invested only the fee for a used stereo with the concern that this will happen again soon. 

Thank you everybody. 

So nobody knows the answer to this, or nobody has ever experienced it? 

Sorry, we have a 95 and 97 Legacy wagons RHD (mail cars). Just a plain radio, nothing fancy. We use a cigarette lighter adapter to charge the phone and run GPS when needed.

Electronics does not like heat. It is hard on the solid state components. I worked with electronics for many years and for an intermittent problem I would use heat and freeze spray to locate the defective part. It's been probably 20 years since I worked on a car radio.

USB is 5 volts, so they will have voltage regulators to provide it. Most USB devices draw less than half an amp so maybe they designed the regulator to supply a half amp. You would think they would have a regulator for each port, but maybe not.