My system keeps killing alternator(S) need help!!!

[wew lad 5,000+ posts]

batteries are going to help but wont help with average load that's above 14v. you're not pulling a lot of load regardless, any alternator and battery set up should be able to keep up. if the red top was drawing excess its likely cumulated on top of the other issues but ive had a bad battery and it didnt kill an alternator on me.

i feel like your pulley ratios were a big problem because ive heard of such on diesel motors. the second issue is heat and thats best addressed with larger cases. having two alternators for the load helps too.

here's a 3rd possibility; your two alternators might be fighting each other causing the voltage regulator to burn up. you really really need to find accurate documentation (or an expert) on these alternators and their regulation

 

[SuperDuty350]

Yeah man, it's been rough, especially dealing with it & having a newborn at home. Which single do you have & which would you recommend for me? What batteries are you running? Like I said, my system pulls 70 amps by itself on top of all the factory stuff. I know my glow plugs pull 60-65 sometimes up to 10 minutes.

I have yellow tops. The alternator I am not 100% certain. Custom Truck and Auto (very reputable operation that only works on heavy duty trucking and equipment) who I used for landscape company put the HD alternator on. I believe it's got 220 amps. I'm not running near the kind of power you're trying to into your system, but I don't think it would matter so long as you've upsized your wire and your electrical system is functioning properly.

Another notorious thing to check on those older trucks is the plug harness at the alternators themselves. They can go bad and short. That's assuming you didn't replace them when you did the dual alt conversion.

One other thing to consider is doing the high idle mod

 

[Papermaker85 5,000+ posts]

batteries are going to help but wont help with average load that's above 14v. you're not pulling a lot of load regardless, any alternator and battery set up should be able to keep up. if the red top was drawing excess its likely cumulated on top of the other issues but ive had a bad battery and it didnt kill an alternator on me.
i feel like your pulley ratios were a big problem because ive heard of such on diesel motors. the second issue is heat and thats best addressed with larger cases. having two alternators for the load helps too.

here's a 3rd possibility; your two alternators might be fighting each other causing the voltage regulator to burn up. you really really need to find accurate documentation (or an expert) on these alternators and their regulation

a dead cell will most certainly cause them to charge excessively.

unless the bridge reflector isn't working its two DC outputs. a burnt rectifier would mean open circuit or you would have a good deal of noise.

the exciter sounds like its not properly working and its overheating from trying to turn on and produce output for the load. id bet its burning up the regulators.

my alt doe that. at idle i am mindful of the current draw. the exciter gets enought voltage when hte alt spins past about 800 RMP...

 

[wew lad 5,000+ posts]

a dead cell will most certainly cause them to charge excessively.unless the bridge reflector isn't working its two DC outputs. a burnt rectifier would mean open circuit or you would have a good deal of noise.

the exciter sounds like its not properly working and its overheating from trying to turn on and produce output for the load. id bet its burning up the regulators.

my alt doe that. at idle i am mindful of the current draw. the exciter gets enought voltage when hte alt spins past about 800 RMP...

i never said it wouldnt cause it to charge excessively, however its not usually so drastic you get a dead short. and if you do have it that bad, dont you think the truck wouldnt start?

if these rectifiers are built with something like chinese 30a diodes then yeah just about anything will fry it and maybe thats the problem

 

[66novals3]

batteries are going to help but wont help with average load that's above 14v. you're not pulling a lot of load regardless, any alternator and battery set up should be able to keep up. if the red top was drawing excess its likely cumulated on top of the other issues but ive had a bad battery and it didnt kill an alternator on me.
i feel like your pulley ratios were a big problem because ive heard of such on diesel motors. the second issue is heat and thats best addressed with larger cases. having two alternators for the load helps too.

here's a 3rd possibility; your two alternators might be fighting each other causing the voltage regulator to burn up. you really really need to find accurate documentation (or an expert) on these alternators and their regulation

Thanks for the reply. I completely agree with you. despite returning the red tops, I have no idea what to use now. I think agm batteries do not agree with my truck/system. it has been a battle that Im over, Im considering just going back to a regular old lead batteries. I also agree about the dual alt setup. I cannot find anyone that's knowledgeable on the subject. I have stumbled upon aviation information where they use a controller to load share. when testing the upper alt with a smaller pulley is the primary alt. eventually the upper shuts its self off and the lower takes over. this happens around 1700-2000 rpm. I have ordered two identical pulleys but I think with running two alternators and realizing nothing is perfect the units will never run perfectly load sharing.

I have yellow tops. The alternator I am not 100% certain. Custom Truck and Auto (very reputable operation that only works on heavy duty trucking and equipment) who I used for landscape company put the HD alternator on. I believe it's got 220 amps. I'm not running near the kind of power you're trying to into your system, but I don't think it would matter so long as you've upsized your wire and your electrical system is functioning properly.
Another notorious thing to check on those older trucks is the plug harness at the alternators themselves. They can go bad and short. That's assuming you didn't replace them when you did the dual alt conversion.

One other thing to consider is doing the high idle mod

Thanks for the reply, at this point I don't know what batteries to use. I did replace both of the alternator connectors and everything in the alternator field circuits test okay. both alternators pass a diode test on my carbon pile and the lower secondary alternator as of last night is dead out of the water. the top one is putting out 100 at idle and 160 at 1500. he seems to be working well, at the moment. high idle mod?? do explain?

a dead cell will most certainly cause them to charge excessively.unless the bridge reflector isn't working its two DC outputs. a burnt rectifier would mean open circuit or you would have a good deal of noise.

the exciter sounds like its not properly working and its overheating from trying to turn on and produce output for the load. id bet its burning up the regulators.

my alt doe that. at idle i am mindful of the current draw. the exciter gets enought voltage when hte alt spins past about 800 RMP...

That's the thing, the batteries don't show a dead cell. but even having 100 amps at idle the voltage does not raise to 14. it just hangs at where they were statically.

i never said it wouldnt cause it to charge excessively, however its not usually so drastic you get a dead short. and if you do have it that bad, dont you think the truck wouldnt start?
if these rectifiers are built with something like chinese 30a diodes then yeah just about anything will fry it and maybe thats the problem

The truck always starts like a champ with theses batteries, I wish I knew the reasoning for the repeat failures. that was kind of my idea of bringing them to a auto electric shop but now I feel like I just got taken for a ride. At this point I am considering a) install the same pulleys and see if they will in fact load share or B) separating the systems and buying a single battery for the audio or c) returning the batteries and alternators and buying a single mechman or similar alternator. knowing I have a junk lower alternator makes me want to head towards option C.

Which option would you pick?

if you chose option b what battery would you purchase for the audio alone at 1600 rms?

 

[SuperDuty350]

Increases rpm when at idle. Can be put on a switch. Google search will tell you better than I can. Lots of northern trucks do this to spread up warming in winter.

 

[SuperDuty350]

Not saying it will fix your issues, but something to consider and should increase your idle voltage

 

[mclerico83 5,000+ posts]

Thanks for the reply. I did a bunch or testing this morning. I nabbed the carbon pile tEster from work and did some playing. What I found is the optimas do not like taking a charge. They are super slow to recover now. My upper alternator is putting out 100 amps at idle and 160 at 1500 rpm. While running the batteries are no longer getting to the 14v range. My lower alt is completely dead. No output even with the upper removed from the equation. Man I'm sick of the ****. I called the auto parts store and they've agreed to buy back the red tops since they are garbage. Considering the glow plugs draw 60 amps for up to 10 minutes i think im going back to regular lead batteries. thinking ofor returning the alternators as well since they are still under warranty from advance auto and the alternator shop. I'm going to add a big 3 and put a large single alt on it.


Thanks for the reply! which company would you go through? I'm looking for quick turn around and good customer support down the road....hopefully this is the end of my nightmare.

singer IMHO

 

[Papermaker85 5,000+ posts]

there Is no need to sync or load share with the alternators. the resistance is the same as long as your wired them properly. its not AC its DC

your exciter uses voltage from the saturation in the windings to turn on your voltage regulator. if the alternator isn't spinning fast enough the induction isn't high enough to turn the alternator on and charge. depending of what type of alternator you have and how its build some using a sensor to power the exciter.

if you are using two different alternators it still won't back feed the other alternator when you have a load of them.

what's the model numbers maybe I can take a look at the schematic.

load sharing is typically done with different phases and its just done really to avoid potential problems overloading the neutral is AC..

 

[66novals3]

there Is no need to sync or load share with the alternators. the resistance is the same as long as your wired them properly. its not AC its DCyour exciter uses voltage from the saturation in the windings to turn on your voltage regulator. if the alternator isn't spinning fast enough the induction isn't high enough to turn the alternator on and charge. depending of what type of alternator you have and how its build some using a sensor to power the exciter.

if you are using two different alternators it still won't back feed the other alternator when you have a load of them.

what's the model numbers maybe I can take a look at the schematic.

load sharing is typically done with different phases and its just done really to avoid potential problems overloading the neutral is AC..

The circuits are about as easy as it comes. One terminal on alt is hot at all times. The exciter circuit has 12v applied to the circuit when cranking or ignition on, it then goes through a 470 ohm resistor that is paralleled with the charge indicator light and straight to the regulator. So, you're telling me that if I had two identical alternators both WITH internal regulators, turning at the same rpm, they should both output the same amperage? These alternators have different ratio pulleys...how ford designed it. This is how they work currently. The smaller pulley alternator fires first. The other puts out a very minimal charge at idle. You get to about 2000 rpm and the small pulley alternator shuts down. The secondary sees this and goes full tilt. I do have pulleys coming to test them being identical. To me, nothing is perfect and I'd bet one fires first and the regulator of the other sees it is not needed, it doesn't turn on. I hope I am wrong for sanity sake. Right now, I have a dead lower alternator, it does have a warranty but I'm still wondering what options to take. Would you attempt to make the 2 alt set up work on the main system or isolate the second alt for audio only or upgrade to one large quality alternator? Using the current set-up is obvious

sly the cheapest....if it works. The isolation set-up would cost me an additional battery+cables ~$350 and the single alternator set-up after returning everything &buying new would be an extra ~$50.

 

[SuperDuty350]

Was your truck stock with the dual alt upgrade?

 

[66novals3]

No, I added the second alternator. It's wired exactly the same as I described above but both have completely separate circuitry. The alternators dying is not new since the dual alt set-up. Everything occurred after the "professional" audio installation. I don't know why in gods name the audio shop didn't recommend an upgrade of batteries/alternator/big 3 with that size system.... But they got their money.

 

[SuperDuty350]

Interesting. From everything I've read, you need to swap out your pcm to accommodate the dual alts. Supposedly the top alternator is the primary, and when the pcm detects the main alt is not sending enough power, it sends signal to kick the second.

I apologize if I'm misunderstanding you. Just throwing out considerations

 

[Papermaker85 5,000+ posts]

The circuits are about as easy as it comes. One terminal on alt is hot at all times. The exciter circuit has 12v applied to the circuit when cranking or ignition on, it then goes through a 470 ohm resistor that is paralleled with the charge indicator light and straight to the regulator. So, you're telling me that if I had two identical alternators both WITH internal regulators, turning at the same rpm, they should both output the same amperage? These alternators have different ratio pulleys...how ford designed it. This is how they work currently. The smaller pulley alternator fires first. The other puts out a very minimal charge at idle. You get to about 2000 rpm and the small pulley alternator shuts down. The secondary sees this and goes full tilt. I do have pulleys coming to test them being identical. To me, nothing is perfect and I'd bet one fires first and the regulator of the other sees it is not needed, it doesn't turn on. I hope I am wrong for sanity sake. Right now, I have a dead lower alternator, it does have a warranty but I'm still wondering what options to take. Would you attempt to make the 2 alt set up work on the main system or isolate the second alt for audio only or upgrade to one large quality alternator? Using the current set-up is obvioussly the cheapest....if it works. The isolation set-up would cost me an additional battery+cables ~$350 and the single alternator set-up after returning everything &buying new would be an extra ~$50.

that make NO sense. who ever decided to do that was a ******* idiot.

thats like saying i want a 1000 watt amp and a 2000 watt amp of the same sub but i want to use the 1000 and 2000 instead of using two 1500s or one 3000.

in short if i was you Id sell the truck apparently its a **** poor design. i couldn't imagine why one alternator would start at idle and another at 2k when a dual alt setup done right could charge plenty @ 600 RPM. its not like its winding out to 7500 rpm and you could damage the alt.

 

[66novals3]

that make NO sense. who ever decided to do that was a ******* idiot. thats like saying i want a 1000 watt amp and a 2000 watt amp of the same sub but i want to use the 1000 and 2000 instead of using two 1500s or one 3000.

in short if i was you Id sell the truck apparently its a **** poor design. i couldn't imagine why one alternator would start at idle and another at 2k when a dual alt setup done right could charge plenty @ 600 RPM. its not like its winding out to 7500 rpm and you could damage the alt.

I agree it's a poor system, in fact I regret ever doing what I've done knowing what I know now. Your response does nothing to benefit the resolution of the issue. I have pulleys coming to make them equal. You seem to be intelligent with electrical and wanted to know if you thought two "identical" alternators with internal regulators, spun by the same prime mover at the same rpm would produce the same amperage.