Charging issue after cold start (1 Viewer)

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aaron9252

aaron9252

Joined
Mar 25, 2012
Threads
28
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119
Location
Mooresville, NC
Starting last week, I noticed my volt gauge not reaching its normal 28 point after starting the LC. Typically, right after I start the truck and hit the gas a little, the meter would jump to 28V give or take.

As of last week, after driving for about 1-2 minutes is when the voltmeter would jump up to its normal 28V showing the alternator was in fact charging.

This weekend I got the multimeter out to test from the battery side after starting cold. After starting, the reading from the batteries showed no increase while running. After idling for about 2.5 minutes, the volts jumped up as if the alternator just all of a sudden started charging.

Once it starts charging, there are no charging issues that I'm aware of.

It's just strange that there's a delay with the alternator function. What should I test at this point? What is causing this delay?

Thanks!
 
I don't have an answer for you, but my HJ61, 12HT 24V does the exact same thing. Seems the colder it is the longer it takes to start charging. I have thought about taking the cover off the regulator to see if I can adjust the settings. I don't know, but I have inferred from other threads that there are threshold settings that control the voltage thresholds for when it starts and stops charging. I don't really know what I'm talking about, but I will be watching this thread because I have the same concerns.
 
X2, I would suspect it's the second stage of the glow plugs
 
I think its an aging regulator. I don't really know but I guess it is probably not good for them either, so I always keeps the rpms high on a cold start, around 950-1000. If you are having that problem the extra rpms will usually make the regulator start charging.
I've seen this problem happen on petrol engines, which is why I don't think its in the glow system.
 
Douglas S said:
Are the glow plugs still running? That would be my uneducated guess.
Click to expand...
Would the glow plug/screen light still be on if it is on/engaged/heating? My light goes off well before the voltage indicator rises.
 
TLink FJ60 said:
Would the glow plug/screen light still be on if it is on/engaged/heating? My light goes off well before the voltage indicator rises.
Click to expand...
No, my understanding is that with a superglow system the plugs will continue to run for a time (determined by temp) once the light goes off.
 
hi ,maybe more causes but one could be this : cold start in winter means that batteries (i think you are 24V but 12v is the same thing) are more stressed and they need to absorb more ampers before reaching the nominal voltage so alternator needs more time .
surely and old alternator with worn brushes helps to increase this delay
i don't think that the voltage regulator is involved because it acts on the charge thresholds

mine bj has the same issue and i noticed that in the summer it reaches 28v faster than winter...

hope it helps
cheers
 
Thanks for the inputs. I'll check the brushes when possible but I had my alternator fully rebuilt last year so it should be good...which is partially why I'm a little perplexed at this.

I wouldn't think the cold effecting the batteries would alter timing of when the alternator starts the charging but then again it seems too coincidental that I noticed this when the weather started getting cold.

Douglas S said:
No, my understanding is that with a superglow system the plugs will continue to run for a time (determined by temp) once the light goes off.
Click to expand...
My glow plug light turns off fairly quickly but I didn't know the plugs could still be running based off of temp. Interesting.
 
AussieHJCruza said:
X2, I would suspect it's the second stage of the glow plugs
Click to expand...

infact if you alt is pretty new.... superglow can be the cause infact it still energizes the glow plugs even after the light goes off .

superglow means 14v glowplug that in the first stage they are energized for a little time with 24v (light on) , in the second stage (light of) they are still energized with 11v for more time(engine running if you start when light goes off)

so you can check : put a voltmeter between +24 and ground (batteries side) and another voltmeter to check the glowbar tension

if the batteries tension rises when the second stage of the superglow is off that is the cause and you don't have a really problem

you can even try to wait untill the second stage goes off and then start engine the tension would rise quikly . looking at the voltmeter you can see when the second stage goes off and you normally can ear the 2° relay click (engine off) , at this time the tension would rise

cheers
 
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Can the original poster specify what vehicle and motor??
I have the exact same condition in my 1989 BJ74 with 13BT. It has the glow screen (not glow plugs) and is on a wilson switch so that should rule out the superglow responses (or at least in my case). My batteries are brand new but alternator is original AFAIK. Just under 300,000km on the ODO and I've had it since 140,000km. Did not notice the low voltage at start up until the -20C temps came. But I run a webasto and never really have "cold" starts. In fact glow screen would not even come on without the wilson switch. Of course batteries, alternator and everything else are super cold.

Edit: see update / correction to this on post #16
 
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I have a 24V 12HT with similar behavior as I mentioned above. Yesterday morning it was 26F outside, so I took a voltmeter and checked voltage on my glow screen electrical connections. I started the engine. The voltmeter on the dash was reading about 18-20V. Voltage on the screen was reading 20V which means the glow screen was turned on. The glow indicator light on the dash was off at this point. After about 60 seconds, the voltage on the glow screen dropped to 0. I checked the voltmeter on the dash and it was reading 26-28V.

In the 12HT FSM I found info that says in cold weather, the first stage of the Glow Screen engages for up to 14 seconds (what is referred to as superglow above?) then after starting, the second stage comes on for up to 70 seconds.

The FSM information and my observations are consistent with each other and with the theory that the apparent lack of charging is due to the excessive draw on the batteries during glow. I do wonder if it is normal that the voltage would drop so low (18-20V) - could be aging batteries.
 
aaron9252 said:
. After idling for about 2.5 minutes, the volts jumped up as if the alternator just all of a sudden started charging.

!
Click to expand...

What happens if you increase the rpms when the alternator shows no output on the gauge?
 
Malahki said:
Can the original poster specify what vehicle and motor??
I have the exact same condition in my 1989 BJ74 with 13BT. It has the glow screen (not glow plugs) and is on a wilson switch so that should rule out the superglow responses (or at least in my case). My batteries are brand new but alternator is original AFAIK. Just under 300,000km on the ODO and I've had it since 140,000km. Did not notice the low voltage at start up until the -20C temps came. But I run a webasto and never really have "cold" starts. In fact glow screen would not even come on without the wilson switch. Of course batteries, alternator and everything else are super cold.
Click to expand...
Edit to my previous post: I was mistaken. If I turn the Wilson switch off for my glow screen after starting the motor the volt gauge will immediately come all the way up to the normal 28V operating point. If I turn it back on it will instantly drop back down again for a couple minutes. So it would appear the glow screen operates the same way as the suggested superglow system.
 
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Malahki said:
Can the original poster specify what vehicle and motor??
I have the exact same condition in my 1989 BJ74 with 13BT. It has the glow screen (not glow plugs) and is on a wilson switch so that should rule out the superglow responses (or at least in my case). My batteries are brand new but alternator is original AFAIK. Just under 300,000km on the ODO and I've had it since 140,000km. Did not notice the low voltage at start up until the -20C temps came. But I run a webasto and never really have "cold" starts. In fact glow screen would not even come on without the wilson switch. Of course batteries, alternator and everything else are super cold.

Edit: see update / correction to this on post #16
Click to expand...

HJ60 2h engine. Comments around of glow plugs pre start and post start (2nd stage) clicking sound are fairly consistent with what I'm seeing.

Only issue that I still cannot figure is that the alternator is not showing any charge right after start. It shows charge 1-2min post cold start. I wouldn't think the glow system has anything to do with alternator charge working or not, correct?

Rather the glow system running would keep the total Volts down some, but not necessarily keep the alternator from not putting out a charge after startup.
 
So tonight it was around 15 degrees. Started the 60, let it warm for 10 min and the gauge read around 15-17V. Got in and drove around for a while and the gauge never increased unlike before.

So I went home and left it running while I got my multimeter out. Hooked up to both batteries and they read 23.05 while idling. When I increased throttle, where I would typically see 28-29 volts with the multimeter it only jumped up to 24.1V. As soon as I decreased throttle back to idle it would drop back down.

Any thoughts to this? I guess I should check brushes at this point even though the alternator was rebuilt last year?

Super frustrating....

Also, as a FYI I have no 12V tapped into either battery.
 
....PROBALLY you are right , only a question :is the alt belt tight ?

i don't know if is this possible but the relay in the voltage regulator maybe is stuck in half charge position or this relay don't operate right .....or all the regulator is corroded and you don't have the correct tension at e/f terminal
so you can try to bypass the external regulator to see if the problem is in the regulator and the alt is ok (put 24 v to e-f rotor terminal, it should show 28/29v at b terminal)

....if no you probally don't have anything to do that pull off the alt and check brushesh , diodes , stator / inductor windings and bearings

maybe diodes are the cause if you say that the alt was rebuilt...

good luck
 
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