Apparent power station drain with nothing plugged in

Had my rockpals charging from a solar panel, it stopped at 99%. Brought it in and within a couple of hours saw it had gone down to 87% with nothing plugged into it. So far it's holding there.

I normally keep it off when not in use but is this normal? I know that the remaining percentage is not accurate with these things but this seems a little much. I'm considering doing a capacity test.

I plugged in a fan with approximately a 60 watt pull. Once the station hit 20% i turned it off. According to my watt reader it used 0.17kwh in 2.7 hrs. The rockpals is rated for a 288.6 wh capacity. So theoretically, taking inefficiencies into account and a starting capacity of 86% (it went down one more percentage)

80% use on ac = 196 watts
66% use = 162 watts
Actual used = somewhere around 170 give or take

So in conclusion ¯\_(ツ)_/¯ worse case i have to take advantage of the warranty and maybe get paypal involved, but hopefully the issue resolves itself.

In conclusion, much like loading statuses on computers, 99% doesn't mean 99%. Fully charged it to 100%, and it has held there since.