Alternator diode heat

[Mopar1973Man]

Something I figured out the other day. I had started my truck cold after doing a valve adjustment and the grid heater was cycling in and out as normal. Then I placed my hand on the back of the alternator near the diode plate and Wow! that thing gets hot. Even with the Quadzilla bumping up the idle to 1,200 RPM with its own high idle the draw of the grid heater is considerable. 

 

I'm starting to think it might a be a good suggestion to replace my grid heater here in the future and see if the diode heat is reduced. 

[Marcus2000monster]

Let us know how that goes Mike. That could save us all a shot alternator not to mention it would reduce AC noise correct? 

[Mopar1973Man]

I'm trying the figure out how to prevent diode damage. I'm tired of changing alternator in the winter. Last winter I changed out 3 alternator.

 

Never a problem all summer.

Edited October 18, 2018 by JAG1

[JAG1]

8 minutes ago, Mopar1973Man said:

I'm trying the figure out how to prevent diode damage. I'm tired of changing alternator in the winter. Last winter I changed out 3 alternator.

 

Never a problem all summer.

I wish there was a way to reduce the amperage demands from the grid heater. I don't know enough on how to do something like that. I've heard about potentiometers? Things like that.

[Mopar1973Man]

Still leads me back to the beginning with my truck. Why is it 10 years can go by and never have an alternator issue now it's a constant battle? The battle begins in the fall and goes to spring. Never an issue in the summer. The only thing I can say is the grid heater degrades over time and creates these issues.

[dripley]

I disconnected mine 2 years ago when i noticed one of the insulator caps on the grids was partially melted. All the rest of the wiring looks fine from the outside but I never investgated it any deeper. Might just replace it and see what happens. Rock auto has a SMP for 110 bucks and an Airtex Wells for 210 bucks. Whats different about the 2 I dont know.

[2000Ram2500]

MSRP on the factory heater is $220.00. Part# 5086720AC

 

What about a capacitor? Something to take the load from being placed directly on the battery/alternator?

Edited October 18, 2018 by 2000Ram2500

[Mopar1973Man]

Capacitor will do nothing load is load 195 amp is still 195 amps. I'm wondering as the grid heaters age if they can possibly get higher current flow. I know science says no, it suppose to be less current flow.

[IBMobile]

Can we get some ohm readings posted to see if the resistance of the grid heaters increases with just age, mileage or on/off cycles.   This would be a good indicator to whether a given ohm reading is pass/fail. 

 

Just tested mine and both came in at .1 ohm with 109,000 miles, used mostly in warm So Cal.

[Mopar1973Man]

When I get home. Ill see.

[dripley]

For the electrically challenged, set meter to ohm then probe the + and the - terminals of each heater??? Correct?

[2000Ram2500]

20 minutes ago, Mopar1973Man said:

Capacitor will do nothing load is load 195 amp is still 195 amps. I'm wondering as the grid heaters age if they can possibly get higher current flow. I know science says no, it suppose to be less current flow.

 

The reason i mentioned a capacitor was because they use them alot on higher power sound systems to provide a barrier between their amplifier and the battery. Its supposed to draw off the capacitor instead of the battery and when power consumption goes away the capacitor recharges itself from the battery. A buffer so to speak. If it wont work it wont work I was just throwing an idea out there.

 

I would be curious to see though if you disconnected the heaters if your diode stopped getting hot and eliminate that as the cause for this.

[dave110]

I maintain the belief that the grids kill alternators which is why mine are on a switch. I don't use them ever, except to pre heat the truck to start then they go off. My alternator problems have went away since doing so. For whatever reason some don't want to switch them. To each their own. The 2 codes it sets don't bother me and I don't have smog here. If I ever do have to get smogged I will turn them back on, clear the codes, do a few drive cycles and get smogged. And apparently @IBMobile has a way to switch them that doesn' throw codes so what's to lose?

 

Anyhow, now that I've made my annual case about switching the grids I also believe something changed since we didn't hear of this problem from new. And Mike unlike many of us has had his truck from new so he would know. Everybody here is all hyped up about grounding mods here lately. One question I asked before that didn't get much attention is what about the grid heater ground? One end is on a long bolt down into the intake plenum which is alum. and corrodes easily. Just a thought.

[dripley]

18 minutes ago, dave110 said:

One end is on a long bolt down into the intake plenum which is alum. and corrodes easily. Just a thought.

That bolt threads into the cylinder head which is cast iron, thats where ground comes from. I ran my AD ground off of one of longer bolts on the horn for 7 years with no issue. There are gaskets between the intake horn, heater, and the intake plenum that would prevent a good ground from the intake horn alone.

 

Prior to doing WT's ground mod I read .035 ac volts off the alternator. After doing the mod I am .01 ac volts. I understand principle of it some what but the results I think speak for themselves. 

 

 

Beware, the chicken man is talking electric again.

Edited October 18, 2018 by dripley

[2000Ram2500]

33 minutes ago, dave110 said:

And apparently @IBMobile has a way to switch them that doesn' throw codes so what's to lose?

 

 

I would be very interested in doing this. I hate seeing how rough the heaters are on the electrical. Watching the voltage go from 14 to 12.5 just makes me cringe.

 

17 minutes ago, dripley said:

Prior to doing WT's ground mod I read .035 ac volts off the alternator. After doing the mod I am .01 ac volts. I understand principle of it some what but the results I think speak for themselves.

 

I can attest to the improvement. While i didnt and still dont have a way to measure milivolts overall the truck drives alot better. Its not just a butt dyno it genuinely drives alot better. Shifting is a glide between gears its nowhere near as jerky as it was before.

Edited October 18, 2018 by 2000Ram2500

[dave110]

23 minutes ago, dripley said:

That bolt threads into the cylinder head which is cast iron, thats where ground comes from.

 

Prior to doing WT's ground mod I read .035 ac volts off the alternator. After doing the mod I am .01 ac volts. I understand principle of it some what but the results I think speak for themselves. 

 

Correct. But the ring terminal lays on aluminum. That was the area of my concern. The dissimilar materials causing corrosion and preventing a good contact between the bolt and ring terminal. Not doubting the mod at all. That's what sparked my thought. I also remember early on in the mod where bolt threads were being wire brushed to make better contact.

Edited October 18, 2018 by dave110

[IBMobile]

1 hour ago, dripley said:

For the electrically challenged, set meter to ohm then probe the + and the - terminals of each heater??? Correct?

That's one way to just test the heaters themselves or one probe on the + side of the heater (firewall side) and the other probe on the - post of the left battery.   This will test resistance through the heater and ground up to the battery.

 

 

22 minutes ago, dripley said:

Beware, the chicken man is talking electric again.

                 

[Mopar1973Man]

2 hours ago, 2000Ram2500 said:

I would be curious to see though if you disconnected the heaters if your diode stopped getting hot and eliminate that as the cause for this.

 

That is true if I unhook the grid heater the diodes stay very cool. 

 

Still, back the problem why did I get 10 plus years of service from the alternator with no issues. Now diodes are constantly overheating and failing? What has changed about the grid heaters to make the diodes overheat? Never had that issue with the truck brand new. 

[dripley]

1 hour ago, dave110 said:

Correct. But the ring terminal lays on aluminum. That was the area of my concern. The dissimilar materials causing corrosion and preventing a good contact between the bolt and ring terminal. Not doubting the mod at all. That's what sparked my thought. I also remember early on in the mod where bolt threads were being wire brushed to make better contact.

One side lays on the aluminum but the other side is in direct contact with the bolt head. No dissimilar material there. So I dont think it matters unless the corrosion wraps around maybe. I have never seen that on mine.. I read a good ground there off of the bolt head.

Edited October 19, 2018 by dripley

[dave110]

15 minutes ago, dripley said:

 unless the corrosion wraps around maybe.