I don't know about a tablet but my Samsung S5 mini phone used to drain a fully charged battery with the phone still being continuously charged in around 5 hours when running the TomTom Sat Nav App. This was with live traffic update mode enabled and when regularly travelling in areas with a iffy mobile phone signal. The higher battery drain may have had something to do with trying to connect to an out of range (out of area) mobile mast.
TomTom did however have other modes of operation where the update rate was slightly slower and with a limited rendering of the graphics (street names not shown on the map etc.) that consumed less power.