2010 Tomberlin Vanish - charging oddity

[beynon]

My vanish is working fine for light use. I went to use it after it had been sitting for a couple weeks and the battery discharge meter showed (30%) the two lowest bars flashing back and forth, which means it needs to be charged. I put on the charger overnight and in the morning the charger showed solid green (full charge complete). Upon inserting the key I expected to see the battery discharge meter to show the 100% bar. Instead it's still alternate flashing the two lowest bars that means 30%.

The batteries are < 2 yrs old and have been watered each time they are charged.

Any suggestions what this means and how to diagnose?

Thanks,
Mike.