It says not charging battery

Hello, there are a couple of thoughts here. I can't imagine a vehicle that starts and runs for a few seconds -- without being jump started -- that will not stay running, unless there is an engine performance issue. Secondly, if you are seeing an indicator that the battery is not getting charged, it probably isn't getting charged. Simple testing of output from your alternator -- both voltage and amperage -- will show what is going on. If there's no output, check the wiring connector and connection to the alternator as well. Also, if you replace the alternator -- it does not necessarily mean the replacement one works! Sometimes replacement alternators fail. Follow through with needed testing.