Battery Power Display

[bubbaberg]

I love the Volt Enduro for what I use it for. However, its a bit concerning when I unplug the charger and shows 88% charge on the bafang display then as Im riding it flucuates between 88 and 92% for the first 10 or 15 minutes and decreases as time moves along. Should this not read 100% after a 10 to 15 hour charge? I feel Im getting shorted on a battery. Shop says its a non issue amd if I press the button on the battery, it shows all 4 bars lit green at 88%. For me its a concern on a long ride