Aging Power Steering or Air Cond impacting Alternator Charge?

[RVR OVR]

I am now on my third alternator (well, 4th, if you consider the one that came with the car. 2 used ones from Will and one rebuilt. All of them have the same problem. With all accessories running, and when in gear stopped at a light, the charge voltages dips below 12. If I turn on the AC, it dips a couple tenths of voltage point lower. Over time, it gets worse as the battery drains. The fan in the car gets slower and light dim a bit.

All the wiring has been checked by a pro (not me), and my mechanic even ran new lines from the alternator to the battery.

I can hear the power steering pump staring to whine, and the AC condenser have never been replaced. I am thinking one or both of these is dragging enough to make a difference. I did see on some other auto forums that people said this caused a problem fixing power steering helped with battery drain.

Any thoughts? I am at at my wits end with this.

Tom

 

[robertf]

If you ever see voltage below battery then something is draining a lot of power. Id recheck fan wiring

 

[discostew]

I would be checking all your grounds. Clamp your positive lead on the battery post then check that you have the same voltage reading at your alternator case that you have at a body ground. I think if you have more than .3 volt difference it means you have a ground issue. Do it with the the key on and the engine off. While you check those you should keep in mind that when the truck is running true ground is the alternator case and true battery positive is the large field terminal on the back of the alternator.

 

[RVR OVR]

I would be checking all your grounds. Clamp your positive lead on the battery post then check that you have the same voltage reading at your alternator case that you have at a body ground. I think if you have more than .3 volt difference it means you have a ground issue. Do it with the the key on and the engine off. While you check those you should keep in mind that when the truck is running true ground is the alternator case and true battery positive is the large field terminal on the back of the alternator.

Wouldn't this be an issue all the time? As soon as I push on the gas and the RPM's go up by a few hundred it is back to 14+ volts.

 

[JohnB]

Maybe check the ac clutch bearing. Had an issue with mine were at idle the belt would start to slip and caused all kinds of havoc.

 

[p m]

A slipping belt would go up in smoke pretty quickly, won't it?

 

[JohnB]

Most likely. Mine was pretty old and glazed and once you put your foot into it every thing worked ok. Real issue was at low rpm power steering was lacking and noisy. Never checked the alternator output but a D2 doesn't have a very reliable idiot light.
Clutch bearing eventually seized and burnt the belt. Leading up to this I had swapped PS pumps with zero change.

 

[RVR OVR]

My belt and pulley were new last time I replaced the alternator less than 5k miles ago, so no worries there. I talked to my mechanic and he said he is not surprised that this is an issue since my son drives this and his trips are a couple miles each, repeatedly throughout the day. So, he is starting the truck a lot and it simply doesn't have time to charge the battery back up. Does anyone else with a D1 have access to a cigarette lighter voltage meter to see if all D1's commonly go low at idle? I might even buy one for somebody with a 1994 or 1995 D1 if you would test it for me.

https://www.amazon.com/Jebsens-Charger-Battery-Monitor-Voltage/dp/B01N00I4TM/ref=sr_1_1_sspa?crid=C6ESVP5V2EVE&dchild=1&keywords=cigarette+voltage+meter&qid=1608234080&sprefix=cigarette+voltage%2Caps%2C181&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVVZEWEVCSFRYRE5XJmVuY3J5cHRlZElkPUEwMzc3NzMxMkxSRU9UTk4zNFBYWCZlbmNyeXB0ZWRBZElkPUExMDQzNDc2NFE4SEdBSTZTU1daJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

 

[nickhand]

My belt and pulley were new last time I replaced the alternator less than 5k miles ago, so no worries there. I talked to my mechanic and he said he is not surprised that this is an issue since my son drives this and his trips are a couple miles each, repeatedly throughout the day. So, he is starting the truck a lot and it simply doesn't have time to charge the battery back up. Does anyone else with a D1 have access to a cigarette lighter voltage meter to see if all D1's commonly go low at idle? I might even buy one for somebody with a 1994 or 1995 D1 if you would test it for me.

I use my D1 all day at working. We grow plants etc out doors. Constantly stopping and starting never had a issue with the battery not staying charged

 

[RVR OVR]

I would be checking all your grounds. Clamp your positive lead on the battery post then check that you have the same voltage reading at your alternator case that you have at a body ground. I think if you have more than .3 volt difference it means you have a ground issue. Do it with the the key on and the engine off. While you check those you should keep in mind that when the truck is running true ground is the alternator case and true battery positive is the large field terminal on the back of the alternator.

Thanks - Did that. Checked it on the alternator and on the winch fairlead. Reading was exactly the same.

 

[RVR OVR]

If you ever see voltage below battery then something is draining a lot of power. Id recheck fan wiring

So, as a test, I drove around with the fan at 4, 3, 2, and 1. It obviously pulls more at 4. I noticed a swing of about .2 - .5 or .6 volts between 1 and 4. When idling, I can get it to drop to 11.9V with the fan on 4 and all accessories on (lights, stereo, etc.). When I drop it to 3, it goes back up to 12.2 and then gets better from there. Any pointers to where to check wiring? Maybe fan is just really old and pulling more than it should be?

 

[ptschram]

Are you certain you have the correct pulley on the alternator? Is the belt routed correctly? Soon, if not my next, I will have the belt routing inked on my forearm!

 

[robertf]

I meant condensor fans. Did you have the AC switch on when you tested the fan switch?

 

[RVR OVR]

I meant condensor fans. Did you have the AC switch on when you tested the fan switch?

I did it with and without. With it, I can lose another .1 or .2 volts.

 

[robertf]

Ok. Not it

whats the batter voltage with everything off?

what is it in key position 1
Position 2
And what is it with all radio/hvac stuff off and engine running?

maybe pull the abs fuse fromunder the hood and see if that stops it

 

[discostew]

If you ever see voltage below battery then something is draining a lot of power. Id recheck fan wiring

But how do we know the battery voltage? And I would also check a body ground. The bumper is a chassis ground. The guage thats got you so worried is on a body ground.

 

[robertf]

Grounds get blamed a lot. They are rarely the problem in my experiences

for a battery to drop from 12.5ish to 12.2 with a running alternator it takes a very low resistance short circuit. Theres not many in a disco that can do that without catching fire.

 

[RVR OVR]

Are you certain you have the correct pulley on the alternator? Is the belt routed correctly? Soon, if not my next, I will have the belt routing inked on my forearm!

Yes, it is the stock pully that came with the truck and everything routed correctly.

 

[RVR OVR]

Ok. Not it

whats the batter voltage with everything off?

what is it in key position 1
Position 2
And what is it with all radio/hvac stuff off and engine running?

maybe pull the abs fuse fromunder the hood and see if that stops it

Thanks - my son took the car to work, will check it out tomorrow.

 

[discostew]

Grounds get blamed a lot. They are rarely the problem in my experiences

for a battery to drop from 12.5ish to 12.2 with a running alternator it takes a very low resistance short circuit. Theres not many in a disco that can do that without catching fire.

I was always told that the alternator case is true ground when the engine is running, alternator field terminal is true positive. The battery just becomes a capacitor. I guess from my way of thinking about these things its the whole difference of potential thing. I'm sure your right that the ground side gets a bad rap, but it's so easy to check I always do that first. On the new Rovers you have junction blocks and cables running the length of the vehicle. First one is right off the battery and then about 5 or 6 battery pos cables heading to other junction boxes. I'm always checking those for voltage drop and find it a lot too.