just bought first bike, battery/charging problem

[carralo1]

Hey guys, new to forum, just bought an 02 gz250. The guy said battery is shot so we jump started it off his truck, everything worked all the lights I mean. Brought it home today and checked voltage of battery 4.7 volts. Jumped it off my truck and read voltage again while running and still 4.7 volts. Gave it some gas to increase rpms and still 4.7. So I aaume theres something wrong with the charging system. How should I go about diagnosing this or is it possible that its just that the battery is too dead... I assume not. Also when I checked out the bike two days ago the turn signals worked but today when I jumped it off they would come on a first which was weird and then when I hit the switch to turn them on, nothing. Also one last thing, when i had the cables connected to jumo the battery, when i went to take them off the battery on the bike, they were very! Hot. Any ideas?