Charging problems

[Irish_Alley]

OK as some know my  alternator crapped out on me on my 200 mile trip. It was reading around 13 volts the whole trip till the last 1/2hr then I slowly watched the volt gauge die. I arrived at my uncles in the early am so I just parked it went out in the morning after a brief nap and the truck of course wouldn't start. So I went to Napa and got a new alternator and put it in but my volts stay a little below 13. Seamed low and I like to see them around 14. So I unhooked the battery for gp and the volts went up to 14+ where I like to see them. I'm going to run the battery into town after another nap but is this odd to have this problem, I mean even with a bad battery last night my volts should of never dropped below 13. Any ideas?

[Irish_Alley]

I can't test the old alternator that I'm aware of due to it being a true one wire alternator and I can't just put it back on the truck cause they (Napa) swapped pulleys

[enaberif]

Batteries can go bad. They can lose cells and they can not work properly under load. I would start with the battery and get it load tested and if the battery checks out then check all your grounds and if that checks out then don't rely on your gauge use a volt meter across the battery terminals with the truck running and lights, wipers and heater on to check for load.

This is a reason why I upgrade to a CS144 for lol! Although that has caused  a couple of issues I need to address nothing major thought.

[Irish_Alley]

Took the battery to autozone, now mind you it can start the truck with no problem. She tested it it tested good but only had 20% charge ( when I worked there our tester would need the battery charged to test it) so she suggest put it on the charger for 1hr and we did. She tested it again it tested bad. Her explanation was the bottom cells could be good while the top ones were bad. Fist time I heard this and I'm ignorant to how batterys are set up but this seam a little weird.

So now it battery shopping time

[jaredts]

might as well go through all of the grounds and battery cable connections while you're at it.  Just to be safe.

[VileZambonie]

lol There's a reason they aren't wrenching and are selling parts at AZ.

So what are you working on? What truck is this?

[Irish_Alley]

this is the 91 crew cab with the cummins

[Irish_Alley]

when i first ran everything a couple weeks ago it was working just fine. i also notices my fuel psi used to be around 12-15 the trip here it was usually around 9-11. dont know if its related or not

[Irish_Alley]

so after the full charge i put her back together volts are around 14 and the fuel psi is about 13-14

[Irish_Alley]

well i should of just went to napa lol. the guy who i got the alternator from at napa was there today, got him to test the charging system in the truck and it was charging good on his tester then he tested the battery and said it was good. it wasnt one of the electric testers like autozone used but the old school style with a temporary switch so it wasnt as sensitive as autozones tester but the battery tested good. so i got the old alternator tested and it was only putting out 10 volts

[LTZ C20]

Well there ya go.