Alt Not Charging

[kongwrench]

'92 chev lumina van 3800
Boosted a truck and now the altenator is not charging the battery.
Replaced the alt with an oem rebuild and it is still not charging. Reading 11-10 volts at the battery with a slow drop while the engine is running.
Reading 1.4V at the large red wire at the alt, is this right?
Cables are clean and tight. Belt is tight with no abnormal noise.

Sorry if this is a redundant post, I am new to this great forum and could not find any simular posts with this same issue.

[loosenut74]

Originally Posted by kongwrench

'92 chev lumina van 3800
Boosted a truck and now the altenator is not charging the battery.
Replaced the alt with an oem rebuild and it is still not charging. Reading 11-10 volts at the battery with a slow drop while the engine is running.
Reading 1.4V at the large red wire at the alt, is this right?
Cables are clean and tight. Belt is tight with no abnormal noise.

Sorry if this is a redundant post, I am new to this great forum and could not find any simular posts with this same issue.

test new alt... while doing this check voltage on large red wire from battery, should be 12+ volts... if alt and volts are right take it somewhere and have a load test done on battery...

[j cAT]

Originally Posted by kongwrench

'92 chev lumina van 3800
Boosted a truck and now the altenator is not charging the battery.
Replaced the alt with an oem rebuild and it is still not charging. Reading 11-10 volts at the battery with a slow drop while the engine is running.
Reading 1.4V at the large red wire at the alt, is this right?
Cables are clean and tight. Belt is tight with no abnormal noise.

Sorry if this is a redundant post, I am new to this great forum and could not find any simular posts with this same issue.

you have a bad alt. or you may have damaged the small field wires/or some how the battery wire to alt is damaged . these field wires create magntic field that causes electic current to be created. make sure those wires have some voltage. the big red wire when properly charging will range from 12.75-14.95volts dc. this range varies because of air temp as well as battery charge condition. you are lucky that this is a easily accessable......did one 2weeks ago.........one point of caution to all never jump start someone with your engine running this is very damaging. this can be very expensive. connect positives first the ground to engine block both vehicles last...... battery explosions occur i know of 2 family members that suffered eye damage......

[j cAT]

Originally Posted by kongwrench

'92 chev lumina van 3800
Boosted a truck and now the altenator is not charging the battery.
Replaced the alt with an oem rebuild and it is still not charging. Reading 11-10 volts at the battery with a slow drop while the engine is running.
Reading 1.4V at the large red wire at the alt, is this right?
Cables are clean and tight. Belt is tight with no abnormal noise.

Sorry if this is a redundant post, I am new to this great forum and could not find any simular posts with this same issue.

one more thing if the alt regulator shorted this could have opened the fuseable link in the wire from battery to alt. [big red wire].........another one more thing charge battery before you complete this repair no sense in damaging new alt by overloading with a half dead battery......

[inafogg]

should have battery voltage to ''Big Red Wire'' 12v check fuses/fusible links.sounds like u may have shorted out when u were jumping car.....
Good Luck

[kongwrench]

I took both alt's in for testing...and they passed. The dude at the counter said check my Haynes manual-wiring diagram for fusible links and something about "other" fuses under the hood. I will have to do more home work with the book.
Odd that its reading such a low voltage at the big red wire though. I would think 13-14v at least there.

Thank you all for the possitive feedback and suggestions. I will keep you posted once I find the trouble spot.

[jeffcoslacker]

It does sound like you'll find a burned fusible link...check primary wire near starter for burns/weak spots...

The large wire coming off the charge post on the alt isn't going to show much or any voltage if it's burned out or necked down at the other end by a torched link...

[j cAT]

Originally Posted by jeffcoslacker

It does sound like you'll find a burned fusible link...check primary wire near starter for burns/weak spots...

The large wire coming off the charge post on the alt isn't going to show much or any voltage if it's burned out or necked down at the other end by a torched link...

you i guess are not aware that inside of the wires there are fuses. these are round pen dia sized plastic that is about 1inch long........with a meter check that you get battery voltages on both sides of wire going to alt. this is not rocket science...........if you did not disconnect battery when replacing alt and shorted out red wire to alt this would explain your current situation........

[kongwrench]

Hello all,
Turns out that the wire at the starter comming from the alt had burnt through. I did not see a fusable link, but the wire acted as one there.
Thank you for the help

[jeffcoslacker]

Originally Posted by kongwrench

Hello all,
Turns out that the wire at the starter comming from the alt had burnt through. I did not see a fusable link, but the wire acted as one there.
Thank you for the help

Fuseable links do not alwyas have obvious fuse sections, regardless of what jcat tried to say...

And they don't always burn all the way through, leaving just enough to cause current drop and strange readings..

I guess he wasn't aware...