Does the battery have to be totally depleted before I can charge it?

We recommend charging the battery pack completely before its first use, or after you have not used it for a long time (the battery should be recharged at least once every six months). It takes about four hours--with the unit turned off--to fully charge the battery.

Other than these two instances, you can recharge the battery pack at any time. The Nintendo DS's power light will change from green to red when the battery life is around 30%.

Note: The unit should not be left uncharged for long periods of time. Leaving it uncharged for long periods (months) may shorten the battery life. As with all batteries, the charge will slowly dissipate if not re-charged, even if it's not turned on.