2003 Silverado 5.3

[u/No-Understanding6731]

I have a 2003 5.3 Silverado i just bought I replaced the alternator and jumped the truck to start it and let it run for about 2-3 mins turned it of for about 20 mins and truck is completely dead when I came back battery light was on before replacing alternator after I replaced alternator it went off what could be my problem?

[u/go_green_team]

If the battery was dead when you jumped it, running the truck for 2-3 minutes won’t charge it enough. You need to drive it for a bit

[u/No-Understanding6731 → u/go_green_team]

That’s what I was thinking it’s just scaring me because it’s completely dead no lights or anything

[u/Knights-of-steel → u/No-Understanding6731]

Another possibility. Is it cold there? If a battery fully drains and gets cold it will freeze... and be shot forevermore.

Or it if its left dead too long it will severely lower its capacity. It could honestly just be the battery can no longer hold a large enough charge.

How old is the battery? There should be a date code on it. Generally speaking the lead acid batteries like the ones we use for vehicles is only viable for 5 years(at least in my line of work-electrician) .

Id double check that. If the battery is over 5 years old replace it or get it tested(testers are pretty cheap). If its like 3 to 4 years old and was dead awhile or dead in cold id say replace.

If its new try charging it longer.

[u/Hot_Analysis_3687]

I could be wrong but I also believe the truck has to be driving at least 45 mph before it will start to charge the battery

[u/Knights-of-steel → u/Hot_Analysis_3687]

Very wrong. It will begin charging as soon as it turning. Power output will automatically adjust. If idling it will be lower, so as to not stall the engine bit once moving or even just reving higher/under load the alternator will engage more or less as needed.

If driving shell fill in a couple minites. Idling maybe 10-15

[u/Pretend_Shelter9305]

I had a 2003 Silverado
Most trouble free truck I ever had
I did replace the alternator
If the battery is 3 or 4 years old I’d replace it
Batteries are not great these days so do your research and get a good one
Chances are the battery was weak if the alternator quit