Batttery Life on my Karoo1

I have had my Karoo 1 for about 3 years now and the battery will not hold its life for more than 1 and half hours which is really disappointing.  My last ride lasted for 1 hour and 1 minute and the previous one was 1 hour and 42 minutes. 

I have gone through my on line dashboard and removed a lot of unused screens etc but my devise will not last very long.  I have ran the battery down to zero and rechanged a few times but its seems to be getting worse.  Please advise?