Author Topic: Charging Light On  (Read 1023 times)

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cfritzel

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Charging Light On
« on: Mar 27, 2021, 06:36:17 PM »
I had noticed my charging light was on about two weeks ago, checked the voltage at the battery while running, with lights on, was around 12.8v. I replaced the alternator and regulator and am now getting about 13.5v while running with lights on. However the charge light still turns on about 5 seconds after I start the truck. Any ideas?

90weight

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Re: Charging Light On
« Reply #1 on: Mar 28, 2021, 05:59:03 AM »
Don’t know what truck your drivin.. maybe check your grounds, voltage regulator?
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cfritzel [OP]

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Re: Charging Light On
« Reply #2 on: Mar 28, 2021, 03:15:04 PM »
Oops, it's an 81 Toyota pickup. Checked grounds they are good.

Snowtoy

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Re: Charging Light On
« Reply #3 on: Mar 28, 2021, 04:16:55 PM »
When you say lights, are they the stock headlights, or aftermarket? 

What are the volts with just the truck running?  Should be 13-15, usually over 14 with a new alt.

If the new alt is a reman from one of the national parts stores, it could be the alt, with those they tend to just replace the part that failed.

Might check the connections from the alt to the battery, the battery's ground.

What is the age of the battery?  If you have a cell going bad, or developing an internal short, that might also be your issue.
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cfritzel [OP]

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Re: Charging Light On
« Reply #4 on: Mar 29, 2021, 12:30:50 PM »
With just the engine running and nothing else on I'm getting 13.5v at the battery. The alt is an Ultima 40 amp (from o'reilly's) (maybe this?). Battery ground is good. Could it be a ground on the relay for the charge light?

Snowtoy

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Re: Charging Light On
« Reply #5 on: Mar 30, 2021, 10:53:51 AM »
I kind of doubt it is the relay ground, since it goes out after a few seconds. 

Does it stay on each time you fire it up, or just after sitting over night?

Might check the voltage drop in the battery over night, if it isn't holding a charge, it could be low enough on start up to trigger the charge light momentarily.  A battery that is on its way out can cause an alternator to over work, which kills of an aged one rather quickly.

The 40amp alt is a bit small, it was designed for a maximum draw of the head/tail lights/HVAC fan/windshield wipers/AM/FM radio on all at once.  If it were me, I would exchange the 40 for a 55amp, regardless of what the battery checks out as.
« Last Edit: Mar 30, 2021, 11:09:28 AM by Snowtoy »
'90 black X-cab mod'd 3.0, 33's/4.88's, rear ARB, custom bumpers, sliders, safari rack, etc.
'91 Blue X-cab 22re, 35's/5.29's,Truetrac front, ARB rear, dual cases, and custom Safari flatbed, bumper, interior.
The money pit '87 Supra resto/mod

 
 
 
 
 

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