Dashboard Alternator light

[eric1514]

Hi all,

The MPPT controller on my coach will deliver 14.6 volts in bulk mode which is fine. In fact it’s exactly what the specs on my GC2 house batteries call for. But when I turn on the engine and the system connects the coach and starter batteries together, the dashboard alternator light will illuminate, presumably because Ford thinks 14.6v is to high.

Couple of questions. Do I care? As far as I know, 14.6v is not excessive and the condition should only last a couple of hours until the charger drops to absorbtion mode and a lower voltage. Or, is there an easy way to reprogram the light or turn it off completely? I’m monitoring all the batteries while I travel with an app constantly running on an old cell phone so I know what’s going on without an idiot light. I can change the profile of the charger to a different battery type and lower the voltage to 14.2v but I don’t wanna if I don’t have to.

TIA,
Eric

[eric1514]

BFL13 wrote:
His sig says:

https://www.rvusa.com/rv-guide/2015-winnebago-travato-class-b-floorplan-59g-tr24274

Seems to be the big brother to the Ram ProMaster City van I did the test with. 🙂 Edit--except ProMasters are Rams, so how can it have a Ford in it? Our little van has a Dodge engine and transmission

Nah, we're talking about the Dynamax in this thread. Sorry for the confusion.

[eric1514]

StirCrazy wrote:

what year is your coach?

Steve

The coach is 2006 Dynamax Isata built on a Ford E450 chassis. It's about 27ft.

[BFL13]

His sig says:

https://www.rvusa.com/rv-guide/2015-winnebago-travato-class-b-floorplan-59g-tr24274

Seems to be the big brother to the Ram ProMaster City van I did the test with. 🙂 Edit--except ProMasters are Rams, so how can it have a Ford in it? Our little van has a Dodge engine and transmission

[StirCrazy]

eric1514 wrote:
Hi all,

The MPPT controller on my coach will deliver 14.6 volts in bulk mode which is fine. In fact it’s exactly what the specs on my GC2 house batteries call for. But when I turn on the engine and the system connects the coach and starter batteries together, the dashboard alternator light will illuminate, presumably because Ford thinks 14.6v is to high.

Couple of questions. Do I care? As far as I know, 14.6v is not excessive and the condition should only last a couple of hours until the charger drops to absorbtion mode and a lower voltage. Or, is there an easy way to reprogram the light or turn it off completely? I’m monitoring all the batteries while I travel with an app constantly running on an old cell phone so I know what’s going on without an idiot light. I can change the profile of the charger to a different battery type and lower the voltage to 14.2v but I don’t wanna if I don’t have to.

TIA,
Eric

what year is your coach?

Steve

[BFL13]

RLS7201 wrote:

BFL13 wrote:
So if that light on means the alternator is shut down, the only amps coming in are from the solar and batteries. Not many solar amps, so battery will run down but with the house batts also on line, that would take longer.

The solar controller would stay in Bulk but not be able to keep the battery voltage at 14.6 for long. What happens next?

In my test when the charger was removed, the voltage went back down to spec, but the light stayed on. I don't know if the alternator came back on. It did when I restarted.

Pretty simple. When the line voltage drops, the regulator does its job and sends voltage to the rotor winds and the generator goes back to work.

Richard

In my test, I was not able to tell if the alternator stopped charging when the voltage got to 14.99 and the engine stumbled but then kept running. The red light came on.

Then with charger removed , voltage fell to 13.8ish and the light stayed on. I think that means the alternator was on then, or voltage would have dropped to 12.x and not been 13.8ish.

So at that point the alternator was on but the red light was on too. I don't know if the alternator ever quit, or just got left behind on supplying amps to the loads when the charger's voltage got the battery higher than the alternator's.

Whatever, the OP wants max amps while driving at the proper voltage for his batts, which is high enough to make his red light come on.

He needs to test when that happens with the monitor set to read the amps to the house batts and not just read the voltage. He needs to see if the alternator is supplying amps added to the solar amps or not when that happens.

If not, then a Dc-Dc charger could help, where it isolates the alternator system from the house system, but still supplies amps to the house to add to the solar's amps, and it can be set to the same proper battery spec voltage as the solar's so they both add their amps fully.

Without them being at the same charging voltage, once the batts get to a higher voltage than the alternator's voltage, no more amps from that source.

If the RV has a gen that can be run while driving, then the OP could have three chargers on the house to bring them up faster like he wants, if he can set the charger run by the gen to the same voltage as the other two are at.

Refer to the thread(s) on how many amps of a DC-Dc charger can be used with how many amps the alternator is so it won't over-heat the alternator. In there is also the way to reduce the DC-Dc draw on the engine batt/ alternator by using fatter wire for the DC-Dc-input.

Also, get more amps by maxing out the roof space with solar if it isn't already.

[RLS7201]

dougrainer wrote:

RLS7201 wrote:
Well now that every one is through guessing, here is what's happening with your alternator light.
The alt light gets a + voltage from the dash when the key is turned on. The light sees a - voltage on the other lead from the alternator when the engine is NOT running and the alternator is NOT producing. When the engine is running and the alternator is producing, the light on the dash sees a positive voltage on both leads and the light is off.
Now when you solar panels gets the line voltage above 14.6, the alternator regulator shuts the alternator down and the dash light sees a - voltage on the lead to the alternator and turns on.
Nothing wrong with you MH charging system.. The light is doing what it should.

Richard

You seem to think people are guessing. Well, I am NOT guessing. My info is FACT. This is direct from Roadmaster engineers over 20 years ago. The Idiot light will work with both the Alternator zero output and OVERVOLTAGE. But, in this case, it is faulting to show OVERVOLTAGE, NOT, that the Alternator has shut down. Doug

Well Doug you may have good info from Roadmaster chassis but in the OPs case, the Ford voltage regulator stops sending voltage to the rotor windings when the line voltage gets to about 14.6 and the alternator stops producing, thus the dash light sees a negative voltage at the alternator and the light turns on.
I have this very same issue on my Ford based MH and have determined the answer with my VOM.
If you have the opportunity to study the Ford charging system on the OPs MH, you will see the issues the dash light plays. It even provided the necessary voltage to the regulator to get the system started.

Thank you for the technical support and documentation that you have supplied the RV community through out the years.

Richard
`

[RLS7201]

BFL13 wrote:
So if that light on means the alternator is shut down, the only amps coming in are from the solar and batteries. Not many solar amps, so battery will run down but with the house batts also on line, that would take longer.

The solar controller would stay in Bulk but not be able to keep the battery voltage at 14.6 for long. What happens next?

In my test when the charger was removed, the voltage went back down to spec, but the light stayed on. I don't know if the alternator came back on. It did when I restarted.

Pretty simple. When the line voltage drops, the regulator does its job and sends voltage to the rotor winds and the generator goes back to work.

Richard

[dougrainer]

Last, in the past 35 years, I have had 2 Automotive Alternators FAIL and at no time did the Idiot light come on to let me know. The only way I found out was the Vehicle drained the battery in transit. Doug

[dougrainer]

RLS7201 wrote:
Well now that every one is through guessing, here is what's happening with your alternator light.
The alt light gets a + voltage from the dash when the key is turned on. The light sees a - voltage on the other lead from the alternator when the engine is NOT running and the alternator is NOT producing. When the engine is running and the alternator is producing, the light on the dash sees a positive voltage on both leads and the light is off.
Now when you solar panels gets the line voltage above 14.6, the alternator regulator shuts the alternator down and the dash light sees a - voltage on the lead to the alternator and turns on.
Nothing wrong with you MH charging system.. The light is doing what it should.

Richard

You seem to think people are guessing. Well, I am NOT guessing. My info is FACT. This is direct from Roadmaster engineers over 20 years ago. The Idiot light will work with both the Alternator zero output and OVERVOLTAGE. But, in this case, it is faulting to show OVERVOLTAGE, NOT, that the Alternator has shut down. Doug

[pianotuna]

eric1514 wrote:
Well, I'm confused.

lol welcome to rvnet!!!

[eric1514]

Well, I'm confused.

[BFL13]

OK, so with over-voltage with the new vehicles (is the OP's that new?) and the battery red dash light comes on from the solar's voltage being over spec, does the alternator shut down or not?

If it does,, will it come back on by itself if the voltage is reduced to within spec (by adding load maybe)

Are there model years where it won't matter like my 1991, but it does matter starting about ? year, where the alternator does shut down, but then later years than that ? year, the alternator stays on and just the light stays on too?

If so, then members will know what to do depending on what year their RVs are.

I had that engine stumble reported earlier, but that 2016 van is a Fiat, made in Turkey with parts from everywhere, so not sure it is typical.

[theoldwizard1]

BFL13 wrote:
So if that light on means the alternator is shut down, ...

Your 1991 E350 is "old school" and works the way others have stated.

Your Chevy likely does not work the same.

[theoldwizard1]

RLS7201 wrote:
Well now that every one is through guessing, here is what's happening with your alternator light.
The alt light gets a + voltage from the dash when the key is turned on. The light sees a - voltage on the other lead from the alternator when the engine is NOT running and the alternator is NOT producing.

Sorry, you information is more than 20 years put of date !

IT DOES NOT WORK THAT WAY ANY MORE.

[BFL13]

So if that light on means the alternator is shut down, the only amps coming in are from the solar and batteries. Not many solar amps, so battery will run down but with the house batts also on line, that would take longer.

The solar controller would stay in Bulk but not be able to keep the battery voltage at 14.6 for long. What happens next?

In my test when the charger was removed, the voltage went back down to spec, but the light stayed on. I don't know if the alternator came back on. It did when I restarted.