Ford Power Stroke Nation banner

1 - 19 of 19 Posts

·
Registered
Joined
·
262 Posts
Discussion Starter #1
What is the purpose of having two alternators?

I'm asking because my truck has dual alternators and I am planning to upgrade / replace them.

When contacting https://www.dcpowerinc.com/ they recommended disconnecting the lower alternator and just going with a higher output single alternator.

Can anyone advise if this okay to do?
 

·
Registered
Joined
·
545 Posts
They figured out how to make a very reliable alternator with good idle rpm output, but with the needs of ambulences, plows, winches etc... instead of using a less reliable higher output alternator they just put 2 of what they knew would work in there.


I personally wouldn't recommend going down to 1 alternator, unless you only need the 1 alternator, (you said upgrade so I figure you have a need) the stock alternators are very reliable and when you start trying to make them produce more power the reliability goes (db electric) the heat significantly increases, and it's a trade off, higher current output @ peak rpm = lower current output @ idle, this can be change with different pullies and high idle chip settings, but this again will increase the heat in the alternator.
 

·
King Dingaling
Joined
·
9,386 Posts
Holy crap!...what are you running to where the stock dual alternators aren't enough???

I have the stock single HO alternator....and I draw alot!



 

·
Registered
Joined
·
262 Posts
Discussion Starter #4
Holy crap!...what are you running to where the stock dual alternators aren't enough???

I have the stock single HO alternator....and I draw alot!
I'm not running anything crazy right now. I'm just wondering if it's okay to disconnect the lower alternator and just upgrade the top one to a 270 amp XP series that DC Power offers.
 

·
Attention Whore
Joined
·
5,183 Posts
The question is WHY do you feel the need to do that ?
Your dual stock alternators will power TONS of accessories....why waste money on something that will have a total output that's possibly less than your stock set-up ?
 

·
Registered
Joined
·
262 Posts
Discussion Starter #6
The question is WHY do you feel the need to do that ?
Your dual stock alternators will power TONS of accessories....why waste money on something that will have a total output that's possibly less than your stock set-up ?
I think one or both of the voltage regulators is going bad. I figured it was a good time to upgrade the alternator with a top of the line model. I just don't want to spend the money for two of them. I'm pretty sure the DC Power 270 amp is more powerful than the stock 110 amp and 105 amp alternators.
 

·
Attention Whore
Joined
·
5,183 Posts
That depends on when it makes it's power. As someone said earlier...some of the higher output versions only really put anything out when rpm's are raised.
At idle they do literally nothing.....somehting to double check before you spend your money.
Something else to consider is how you're really gonna use it. If you don't have eleventybillion lights and a ginormous stereo system...why bother ?

I have a stock 140 amp alternator, it runs the truck and all it's stuff, driving lights, multiple gauges and a 2000 watt audio system that pulls 160 amps at full tilt. I upgraded all my underhood power wires and every ground in the truck and I cannot make the headlights dim even with everything full blast, AC included.
 

·
Registered
Joined
·
262 Posts
Discussion Starter #8
That depends on when it makes it's power. As someone said earlier...some of the higher output versions only really put anything out when rpm's are raised.
At idle they do literally nothing.....somehting to double check before you spend your money.
Something else to consider is how you're really gonna use it. If you don't have eleventybillion lights and a ginormous stereo system...why bother ?

I have a stock 140 amp alternator, it runs the truck and all it's stuff, driving lights, multiple gauges and a 2000 watt audio system that pulls 160 amps at full tilt. I upgraded all my underhood power wires and every ground in the truck and I cannot make the headlights dim even with everything full blast, AC included.
The DC Power alternators claim to have 2/3 their rated amperage at idle. I'm considering the 270 amp version. I just want to be ready for any future plans, stereo, maybe a few other accessories.

Their top of the line stuff the XP line only comes in the higher rated versions. I think 230 amos is the lowest in that line. And, their XP is the only one that includes all the heavy duty internals. Check out their site they cover it pretty well, and they look like nice, well made pieces.

https://www.dcpowerinc.com/dc-power-vs-competition
 

·
I FINALLY JUMPED!
Joined
·
516 Posts
Do the older trucks have lower amps for dual alts? I think mine said i have 355 amps with the duals? And the HO single is 260 amps. I dunno about the older trucks though. I wouldnt want to just disconnect it. IT would be another failure point that you could eliminate by just removing the alt all together. If a bearing or something went out then you'd be sol.
 

·
Registered
Joined
·
262 Posts
Discussion Starter #12
Still looking for an answer to my original question.

Does anyone know if it is acceptable to disconnect the lower alternator?

Will the truck's PCM be affected in any way if this is done?
 

·
All done now
Joined
·
22,486 Posts
The PCM could care less if you have 1 alternator or 50 of them.

Myself, if my truck had 2 alternators, I would leave them in. That way, if one goes out, unless it is a bearing that goes out, you are still capable of driving down the road at night. To say nothing about being able to replace them cheaply. I love redundancy.
 

·
I FINALLY JUMPED!
Joined
·
516 Posts
Supposedly the pcm programming is different for single and dual.
 

·
Registered
Joined
·
545 Posts
I believe the PCM controls th field excitation circuit to both alternators if you disconnect the lower one you will most likely end up with a code... You could either get the PCM reflashed for single alt or make a resistor harness to fool the PCM to think you still have the lower alt installed
 
  • Like
Reactions: rogerdale38

·
Registered
Joined
·
262 Posts
Discussion Starter #16
The PCM could care less if you have 1 alternator or 50 of them.

Myself, if my truck had 2 alternators, I would leave them in. That way, if one goes out, unless it is a bearing that goes out, you are still capable of driving down the road at night. To say nothing about being able to replace them cheaply. I love redundancy.
I believe the PCM controls th field excitation circuit to both alternators if you disconnect the lower one you will most likely end up with a code... You could either get the PCM reflashed for single alt or make a resistor harness to fool the PCM to think you still have the lower alt installed
Assuming the truck (PCM) would operate on one alternator, you're right. It is probably best to leave them both intact.

Now the question is, do I put the best, highest amp rated alternator in the top position?

And, possibly a lesser expensive lower amp rated alternator in the lower position?

I'm assuming the upper alternator is the main one??
 

·
Registered
Joined
·
1 Posts
I know I am reviving a long dead thread, but couldn't let this go. I removed the lower alternator and replaced the upper one with a higher output alternator because neither one provided enough current to maintain the health of my FICM (6.0L). Additionally, you cannot just remove the second alternator; you also have to rewire so that the PCM doesn't try to select the missing alternator. It randomly selects one of the alternators at start. If it selects the missing alternator, and you have not rewired to account for the missing unit, you are not charging your batteries, which are providing all the voltage to run the vehicle.
 

·
Registered
Joined
·
3 Posts
I believe the PCM controls th field excitation circuit to both alternators if you disconnect the lower one you will most likely end up with a code... You could either get the PCM reflashed for single alt or make a resistor harness to fool the PCM to think you still have the lower alt installed
My 04 f350 will throw a code if one or the other fails.
 

·
Registered
Joined
·
248 Posts
Great, but this thread is now 10 years old.
 
1 - 19 of 19 Posts
Top