So today I was out for an evening joy ride and by chance, as it was getting dark and I hadn't turn on the headlights I noticed the battery light barely lit at idle.

So whats causing? it can you advise me on the proper idle voltage?

 

Edited 18 December, 20214 yr by Thefeliciahacker

The charging voltage gets really low, around 12 volts and under when coming to a stop or at idle. Maybe you have the same issue. Together we might be able to figure this out.

 

 

 

In this video I attempt to solve a low voltage issue I'm having in my 1995 GMC Suburban 5.7L. I recently installed Flex-A-Lite dual electric fans in place of my stock clutch fan and they work great but I'm now having a low voltage issue while idling at a stoplight. I've also upgraded my stock 105 amp alternator to a Powermaster 140 amp.

 

 

 

53 minutes ago, D.FYLAKTOS said:

I recently installed Flex-A-Lite dual electric fans in place of my stock clutch fan and they work great but I'm now having a low voltage issue while idling at a stoplight.

Is your Suburb running the fans in this situation? I think it might be if they replace a fluid coupling fan.

Well guys the car was idling with no electrical load whatsoever being place on the alternator. 

I want measure the voltage at idle and that why I'm asking. 

 

4 hours ago, Thefeliciahacker said:

I want measure the voltage at idle and that why I'm asking. 

 

How To Check Your Car Battery Voltage

https://www.hondaofslidell.com/how-to-check-your-car-battery-voltage-slidell-la/

 

How to Test Your Battery Voltage with a Voltmeter

https://www.goauto.ca/blog/how-to-test-your-battery-voltage

 

At idle, most charging systems will produce 13.8 to 14.3 volts with no lights or accessories on. A discharged battery will have a voltage of about 11.2 volts or less.

4 hours ago, Thefeliciahacker said:

Well guys the car was idling with no electrical load whatsoever being place on the alternator.

I find that hard to believe, if there are no changes other than the fan swap. If anything I'd expect removing a mechanical fan to raise the idle speed because the load on the engine is reduced. This, in turn, means that the alternator will be turning faster, which generates a higher voltage.

A dimly lit battery light with engine running is usually associated with one of the rectifier diodes having failed or become disconnected. Either the big ones in the stator circuit or the small ones in or supplying the regulator.

 

Idle voltage with little auxillary load should be be around 14 to 14.3 volts maybe a little lower in high temperature environments.

Edited 19 December, 20214 yr by xman

The diodes were replaced many years ago. 

Voltage should be close to 14V - Magneton alternators used in 1.3 have poor performance at idle, but if it goes below 13V with no load at idle, something's wrong.

5 minutes ago, Papez said:

Voltage should be close to 14V - Magneton alternators used in 1.3 have poor performance at idle, but if it goes below 13V with no load at idle, something's wrong.

I will check and report back

On 19/12/2021 at 14:13, xman said:

A dimly lit battery light with engine running is usually associated with one of the rectifier diodes having failed or become disconnected. Either the big ones in the stator circuit or the small ones in or supplying the regulator.

 

Idle voltage with little auxillary load should be be around 14 to 14.3 volts maybe a little lower in high temperature environments.

Exactly. In these cold days I get full 14.2 sometimes even 14.3 at most. (Idle with no extra electrical load)

My alternator is the 55A model.

 

 

On 21/12/2021 at 11:48, Thefeliciahacker said:

I will check and report back

Check carbon brushes and integrity of the slip rings/armature.