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

[pianotuna]

eric,

Alternators are rated in amps. Mine is 130 amps. However they are not made to run 'flat out'. The "usual" number (so I'm told by others) is about 1/3 continuous. So my 130 amp alternator can really only provide about 43 amps continuous. Of course, some amps are needed to keep the engine and other devices working.

There ARE continuous output alternators, but they may be a big chunk of change.

There are also external diodes that can be added on. But that is beyond my skill set.

That is why one needs to know the peak output of the alternator--and then not take it up to that for very long.

Generally with modern vehicles the computer (ecu) decides what alternator output needs to be to recharge the chassis battery after starting. That doesn't take very long, so house bank charging is often slow.

I do have a dc to DC charge controller--but it is not yet installed. I chose to use one that is limited to 20 amps output, because the input may well be 30 amps. The dc to DC boosts the voltage so that the house bank will charge faster. In other words, it over rides the ecu and draws more amps from the alternator. It does this by raising the output voltage--so more amps will flow.

Renogy makes one that is a 40 amp output--but which has a jumper that can be removed to limit it to 20 amps.

If you want a "top drawer" device Victron makes one, too.

BFl13 has a unit from Renogy and it works well for him.

[eric1514]

pianotuna wrote:
eric,

That is exactly what a dc to DC charge controller does--it is a diode--but one that can pass a lot of amps.

Now you need to know the duty cycle and the amps output of the alternator

When I look at the simple wiring diagrams for installing a DC to DC charger, I see a set of cables from the starter battery to the charger and from the charger to the house batteries. Seems simple enough. Of course I'd be going through my shunt and I'd need a signal to turn it on. I get scared when I look at the 30 or so other wires in that photo I posted. Other than that...

Why would I need to know the duty cycle of the alt and how would I find out? And are you ever in ID?

[pianotuna]

eric,

That is exactly what a dc to DC charge controller does--it is a diode--but one that can pass a lot of amps.

Now you need to know the duty cycle and the amps output of the alternator

[eric1514]

pianotuna wrote:
eric,

It gives you control over whether there will be charging or not. Personally I'd put a dc to DC charger in.

I think what I am going to try and figure out how to build is a diode (if that's the right piece) with a remote manual bypass so that I can stop solar from going to the chassis battery but continue to receive alternator output to the house batteries while driving during the day. I think it could be inline with the cable that runs from the BIRD to the chassis battery. When I'm parked, I could bypass the "diode" and let shore, solar or generator juice flow wherever it's needed, like it does now. I would think I could build something like that for not a lot of money.

[eric1514]

pianotuna wrote:
eric,

It gives you control over whether there will be charging or not. Personally I'd put a dc to DC charger in.

I've got a bunch of testing to do before I get to that point but it is a very good option. The purpose of the solar was to augment the woefully low alternator output so maybe if the switch cuts off alt output to the house, it might not be a big deal.

But to drive home how little I know about the present system, is the solenoid the lower of the two canisters in my photo?

EDIT: Nevermind. That's the Auxiliary Battery Disconnect.

[pianotuna]

eric,

It gives you control over whether there will be charging or not. Personally I'd put a dc to DC charger in.

[eric1514]

pianotuna wrote:
Hi,

Just look at the solenoid. There are two skinny wires. Put a switch in the positive lead.

Won’t that also keep the alternator from charging the house batteries?

[pianotuna]

Hi,

Just look at the solenoid. There are two skinny wires. Put a switch in the positive lead.

[eric1514]

wnjj wrote:
...On second thought, why not just install a manual switch or switch the controls a relay?

pianotuna wrote:
I have manual control over my charging solenoids.

I would love to have a switch on my dash that turned off the solar to my chassis battery but again, that is all above my pay grade. Looking at this I wouldn't now where to begin.



When the weather gets more cooperative, I have some tests to run and it may turn out that this is nothing more than a light that needs to be ignored for a couple of hours a day.

[pianotuna]

I have manual control over my charging solenoids.

[wnjj]

eric1514 wrote:
It would be nice if I could disable the chassis battery charging from the solar while the alternator is running but I'm not that smart. I'm going to study the wiring diagram but this is not my line of work.

You need a relay with the charge line routed through the NC terminal and the coil powered by an ignition source (i.e. on when running) from the fuse box.

Basically like an isolator relay, but by using the normally closed connection it will open when running.

The problem is if you are driving at night and solar isn’t putting anything out you lose the alternator charging the house batteries.

On second thought, why not just install a manual switch or switch the controls a relay?

[abdulal]

is your ***Link Removed***car insurance paid already?

[eric1514]

pianotuna wrote:
eric,

I think you mentioned you use a trik-l-start. If wired between house bank and chassis battery there will be up to 5 amps of charging. This would also happen with the generator powering the converter.

Let me know if I am not remembering correctly.

This coach does not have a or need a Trik-L-Start. That was in my Class B. Funny thing, I bought one to install in this coach before I understood how the battery control system worked and it is on a shelf in my garage.

Simply put, the battery control in this MH will charge both battery banks if it senses a charge on either one, from any source. The alternator will charge the chassis and house batteries and shore, generator or solar will charge the house and chassis batteries. It will isolate them during discharge. It's pretty slick but it's also the reason I'm having issues with my charge light.

[pianotuna]

eric,

I think you mentioned you use a trik-l-start. If wired between house bank and chassis battery there will be up to 5 amps of charging. This would also happen with the generator powering the converter.

Let me know if I am not remembering correctly.

[eric1514]

BFL13 wrote:
...snip

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.

That's a good test to perform and I'll do it. I can read amps going into the house batteries with the engine on and with it off and do the math. I am curious as to what the alternator is doing when the alt light is lit. I don't have a clamp on amp meter but this might be a good excuse to buy one. I could then test the alternator directly.

BFL13 wrote:
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.

I don't think a DC-DC charger is in the works mostly because the removal of the present system, which works really well, would be more complex than I think I'm capable of.

BFL13 wrote:
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.

The coach has a generator but running it while the engine is on would, I think, present the same problem the panels are causing. The generator runs the converter which charges both battery banks. In truth, I've never done it so I'm not 100% sure about that.