Need power, be skeptical

We have accepted and donated phones to womans' shelters for years. No power means no erasing. To get a phone back into shape, they need a power charger, and usually a new battery since you are getting rid of a used phone. As wonderful as the donation sounds, it costs our company $25-45 per phone on average to "donate" it. When we cannot find a power charger or battery, we drill the phone like you would a hard drive and then send it to recycle.
The data on the phones we receive is amazing. We accept AT&T, Verizon, Nextel, Sprint, Boost and all the weird off shoots and most prepaid. We no longer accept analog phones. You cannot even dial 911 on those.
Even if you erase your contacts, there seems to be some sort of flash memory that holds you recent call list and on some models, pictures and text messages. We simply dial each phone ten times to a number such as 555 and that almost always cleans it out. The rest is performed manually.
To my knowledge, there is no charity that has technicians with these abilities. It is not worth their time or the money it would take to keep a trained technician, so be skeptical if they say they wipe out everything. I have picked up phones in said stores and seen contacts, call history, pics and text, etc.
Do everything yourself or best, take it to a trained store and pay them a few dollars to wipe it for you.