For a first charge, I will recommand something like 16hours at least. For the other charges, I recommand about 6-10hours. A longer charge does not hurt the ti 84 plus C se (it was a problem with old elec devices). With the dock you can charge 10 ti 84 plus c se, it will last a night More informations about th echarging in general : Recharging: two terminals on the lower sides Power: Rechargeable lithium-polymer battery, ~5-10 hours of use Battery Life: Officially 5 days of classroom use or 2 weeks of homework use