I use the regular old car charger that i've used with my last few phones. it seems to keep up when using the phone at the same time as charging. if you already have an old car charger you may want to give it a try. alternately you could get a three prong adapter for your car and just use your regular charging cord such as this.....
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i have not this same model but one like it, and we use it all of the time. more flexible that just a cell phone charger. you can plug in anything, tablet, laptop, phone, etc.