Charging Issue (?) 85 720

[Tanken]

I kill my truck a lot by leaving the lights on since my chime doesn't work so I always carry a portable jumper (which has saved me so many times), anyways I have noticed after I do kill it and jump it, my truck doesn't seem to recharge so from that point on, I have to jump it at almost every start until I can get home to hook it up to a charger. It doesn't matter how far I drive either. I also bought a brand new battery. Yesterday I took off my alternator and took it to autozone and it passed the test. Does anyone have any advice on what else could be the issue? I do have an aftermarket head unit installed but I wouldn't think that would keep the alternator from recharging my battery. The generator dash light isn't on or anything but yes the bulb does work. Any help is appreciated.

Edited October 17, 2023 by Tanken

[thisismatt]

Check voltage at the battery while running. If it's not above 13.3-13.5v then the alternator is not pushing enough voltage to the battery to charge it. AutoZone will still test this as good, but it's really not sufficient to push a charge into the battery.

[thisismatt]

...if you kill the battery dead and only jump start the vehicle you run the risk of damaging the alternator. They are not designed to pull a battery up from that low a voltage, ask me how I know.

[Tanken]

2 minutes ago, thisismatt said:

Check voltage at the battery while running. If it's not above 13.3-13.5v then the alternator is not pushing enough voltage to the battery to charge it. AutoZone will still test this as good, but it's really not sufficient to push a charge into the battery.

 

I believe i checked this a while back and it was good but i'll have to check again. That makes sense but that's been my only option to get home when it dies. 

[Thomas Perkins]

Have your brand new Battery tested?Also Check your black fusible link wire.It could be melted.

Edited October 17, 2023 by Thomas Perkins

[datzenmike]

Also clean the battery posts and cable ends. If poor contact it won't turn over with the starter very well but will with a jump start because it clipped to the cable ends.

 

Start remembering to turn the headlights off.

[Tanken]

1 minute ago, datzenmike said:

Also clean the battery posts and cable ends. If poor contact it won't turn over with the starter very well but will with a jump start because it clipped to the cable ends.

 

Start remembering to turn the headlights off.

all that has been done. i mean yeah that's a solution to it not being completely dead but it still doesn't charge. 

[Tanken]

9 minutes ago, Thomas Perkins said:

Have your brand new Battery tested?Also Check your black fusible link wire.It could be melted.

battery should be good but I should check. I will have to give that a shot

[Crashtd420]

Personally it sounds like you are only running off the alternator other wise you'd be slowly dying while driving...  eventually the power would be low enough to cause issues...

 

I'd be looking at the wiring....

As other have mentioned...

Check the fusible link, clean your terminals.... even check the other end of the ground cable .. make sure that connection is good too.....

[Tanken]

16 hours ago, thisismatt said:

Check voltage at the battery while running. If it's not above 13.3-13.5v then the alternator is not pushing enough voltage to the battery to charge it. AutoZone will still test this as good, but it's really not sufficient to push a charge into the battery.

just tested. got a solid 13.4v with lights and other accessories on

[Thomas Perkins]

Are you using a 50 or 60 Amp alternator.

[Tanken]

18 minutes ago, Thomas Perkins said:

Are you using a 50 or 60 Amp alternator.

i'm not sure. it's an oem remanufactured alternator. i have AC if that can determine it

[Crashtd420]

1 hour ago, Tanken said:

i'm not sure. it's an oem remanufactured alternator. i have AC if that can determine it

I believe the 60 is for the ac trucks but a good upgrade if you have the 50....

[thisismatt]

1 hour ago, Tanken said:

just tested. got a solid 13.4v with lights and other accessories on

 

Not good enough. That's only float/maintenance voltage, meaning after you start the vehicle the battery will become weaker every time. Get a new alt or rebuild yours.

[DwayneOxford]

I wired in a relay from accessory wire to turn headlights off.

[Tanken]

16 minutes ago, thisismatt said:

 

Not good enough. That's only float/maintenance voltage, meaning after you start the vehicle the battery will become weaker every time. Get a new alt or rebuild yours.

ah i see. thank you.  it sounds like my alternator was the issue after all.

[Thomas Perkins]

I use a 60 Amp alternator.The 50 amp one is too weak.I have a a.c.

[datzenmike]

60 amp are standard 720 equipment in Canada. Starters are also gear reduction.

[Thomas Perkins]

Here are some things to do.I just took my alternator off to fix my coolant leak at the hose under it.The black wire at the top of alternator with the phillip head and the white wire with the nut holding it on coming from the fusible link.I got my 3m scrub pad and cleaned both fittings.I then took the negative cable that is the ground cable at the power steering bracket and cleaned it along with the other end.Guess what,now my clock on my radio will keep time.I thought it was the radio.I guess it was cause of the wires not getting a good connection.The white wire did have green corrosion on it.My Amp meter has gone up a little too.When I tightened my alternator belt,I put a black mark on the alternator and the bracket to let me know if the alternator has ever moved.