Everspring SP814 Battery level always 100%

Can anyone help me please?

I have three Everspring SP814 motion detectors included to my Vera Lite.
The battery is always at %100, with a little lightning bolt through it.
These are being battery operated.

I know the batteries are not actually at %100 because one of them recently ran out of battery with no prior warning.
In fact Vera still reported battery as %100 even when they ran out.

Is there something I can do to get these to start reporting the battery status correctly?

Kind Regards