Is my Japanese Softbank phone okay to charge in America?

[FlowingStarlight]

I have a prepaid phone from Softbank (OTCPK: SFTBF) in Japan for use in Japan, in February. The Softbank 822P, to be exact: http://mb.softbank.jp/en/prepaid_service/model/822p.html One day, I wanted to read my old e-mails, so I plugged it in, to charge it. When I did this, the service light started blinking red. It's never done this before. It either stays red constantly while charging, stays green, plugged in, the indicate that it's done charging, or uses the service light when receiving a call or mail. My friend, who has a different model, different brand of Japanese phone, said that it might just be the fact that the battery hasn't been used in a while, and needs extra charging. I'm worried that since the electric current in America is higher than that in Japan, it's going to fry the battery, if I try to charge it. Does anyone know why the light might be blinking like this? Am I okay to charge my phone in America, or should I just hold off until I get back to Japan?