Brandnew Sansa Clip+ from 2010 battery shows always 3%

I bought a brandnew clip+. Fully charged but the battery only shows 3 or 4%. The player still plays. What can I do to improve the battery life? Thank you.

Try a firmware update. Latest is 1.02.18

Run it thru a few charge/discharge cycles:
Leave on charge overnight. Make a playlist that is at least 20hrs long, then have your clip+ play through them all on full volume, make sure to plug headphones in it. Leave in a drawer somewhere. Come back in 24hrs and turn back on (player should have enough juice to turn back on). Mark where it stopped and calculate how long the battery held for. Repeat a few times and see if the battery life improves or not.
Battery is rated for about a 15hr run time. I average about 11-12.5 hours on the ones I’ve tested. If battery life is significantly less, replace it. Batteries don’t last forever. A new compatible battery is roughly $6 on eBay. Search for 303035 battery (a tiny bit smaller but works)