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eric1514's avatar
eric1514
Explorer
Jul 31, 2021

Dashboard Alternator light

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
  • It is not the voltage as such, but something is wrong. First try it with no solar connected to the house batts.

    Is the controller chassis grounded to the RV frame? If so disconnect that. Perhaps there is a polarity problem with how it is all wired and that is what the dash light is not liking. ( WAG) . Anyway the solar and alternator charging should play well together. Something is wrong with your wiring of the solar and the isolator outputs most likely. IMO suspect the solar installation, as the RV will be ok if as built.

    IMO don't drive around much like that until it is fixed.

    One thing to expect is that on the house batts if solar gives you 10 amps at 14.6 and alternator gives you 10 amps at 13.8 doing it one at a time, you will not get 20 amps with both on. You might get more like 10 from the solar and 5 from the alternator with its lower voltage. but that is not the issue here.
  • I have experienced the same issue as you. I just turn off the solar when traveling and let the alternator do it's job.

    Richard

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