I recently got a new GPSMAP 65s hiking GPS and Garmin NiMH battery pack, and when I unplug it after letting it charge overnight, it only shows 2 of 4 bars. Charge only lasted for about 5 hours of tracking (not using the screen to navigate) - I'm not that familiar with this unit but that seems low. The battery type selection does not appear under settings, so it does appear to recognize this battery as the Garmin pack. Device showed a full charge with a pair of Alkaline AA batteries. Is there some setting that I'm missing or is my rechargeable battery just defective?