Look at your charger (aka: "Wall Wart"). If it says 125mA on the label than you will top off that 1500mAh battery in 12 hours. If it says 150mA then ten hours is enough. But if it says 60mA then you'd need 25 hours for a full recharge. Now here's the rub. The rating assumes you are at a discharge level of 1.0 volt or so. If you are higher you don't need as much time. If you are lower you will need more time.

At some point it will really pay to get a charger/discharger that displays battery and charge information. You really can't hurt a battery with the original wall charger. A Fast/Field/Quick charger, however, can fry things (battery or vehicle upholstry) if misused. Depends on the unit's output, of course. 1.5A would charge your battery from "empty" to "full" in 1 hour. I see people blasting AA size receiver packs with 5 amps to try for a 15 minute quick charge at the field and I think that's a bit alarming. You can maybe do that with C size cells but it's tempting fate with an AA size.