The Riva 510 (and probably most other lithium battery) instructions say to charge the battery, even if the light is green, for 8 hours when first using it. Then, take it off the charger, use it for 20 minutes, then charge it again for another hour. Is this necessary? I didn't do it with my Riva batteries because I didn't see that part in the manual that came with it until after I began using it. I hooked them up until the lights changed green, but took them off right after. Could it harm my battery life if I didn't follow these instructions?