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Thread: Furrion MPPT 25A Solar Charge Controller issue?

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    Furrion MPPT 25A Solar Charge Controller issue?

    My 2021 Transcend that I picked up in December 2020, included the solar package with 165W Furrion solar panel and this Furrion MPPT 25A charge controller. Also, I had the dealer throw in a 2nd battery (basic Interstate). Trailer was plugged in the first couple of months, but hasn't been for the last month or so, and I've noticed battery readings different than what I would expect when I casually check with my handheld DMM. I recently installed a basic battery monitor and am more closely checking the behavior. (Unfortunately, the battery monitor doesn't keep a history, so I'm having to spot check. Nor does it indicate current direction - charge vs. draw). Here is what I've seen so far.

    Several weeks ago - observation that made me pay more attention (before battery monitor installed)
    Battery reading = 12.6V
    -I don't recall if battery disconnect was in on or off position, but even if "on" (i.e. connected), everything that could be turned off was...including fridge. So current draw should have been very low. Weather had been decent, so I would surely have expected solar to keep batteries fully charged. In fact I would have expected to read the float charge level specified in the manual (13.2V). This reading was during the day on a sunny day. Charge controller is set to correct type of battery, and main LED was blinking green indicating it was charging (per the manual). In poking around, I physically disconnected the battery terminals and looked them over. When I physically reconnected the battery, I then measured 14.3V, which is what the manual shows as the "bulk" voltage level. So, it would appear like physically disconnecting and reconnecting the battery reset something in the controller, and then it started charging. That doesn't seem right.

    Yesterday - with battery monitor installed
    Battery reading = 13.2V (float level), fluctuate between 0mA - 100mA (I'm assuming that is how charge controller maintains float level)
    Checked around noon, partly cloudy
    Battery disconnect switch set to "off" (i.e. disconnected), so there shouldn't be much if any current draw

    Today
    Battery reading = 12.9V, 0mA
    Checked at noon, overcast sky.
    Battery disconnect switch set to "off" (i.e. disconnected), so there shouldn't be much if any current draw
    Main LED blinking green on charge controller, indicating it thinks it's charging as normal
    It would seem to me the charge controller got back into the non-charging state for some reason. I would expect it to still be generating a little bit of power even with overcast skies.
    I set the battery disconnect switch to "on" (i.e. connected), so see if that draws the battery down. As expected, current reading jumped to ~115mA. Thinking maybe charger won't re-engage until battery drops to a certain level. But I don't think that would be desired behavior.

    I'll check again later and post my observations.

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    Setting Up Camp sirtate's Avatar
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    Following....

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    Site Team Ynot4me2's Avatar
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    FWIW for your investigation, even with the battery disconnect on, there's some what we have come to call parrisitic draw from things like the CO2 sensor that are always on. It's not much though.
    Steph & Lise
    2019 F150 Lariat 2.7 EB
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    I periodically checked on the battery yesterday and today. Pretty consistent behavior with battery disconnect set to "on" (i.e. connected), there was about 120mA draw, and with the battery disconnect set to "off" (i.e. disconnected) there was no current flowing through the shunt. As a result, the battery voltage slowly dropped to 12.6V since I left the battery connected. Yesterday was overcast all day but today had the sun poking through the clouds on and off. Today, during a bright sunny moment around 2pm so solar panel was in full sun, I checked and saw similar behavior. Shunt measured ~120mA with battery connected and 0mA with battery disconnected via the switch. All the while, green LED is blinking happily on the controller. So, with battery disconnected via the switch, I physically disconnected the negative terminal for a moment and reconnected. As I had observed the other day, voltage immediately jumped to 14.2V and with 2-3A going through shunt. That tells me the controller somehow gets into a state where it thinks it's charging, but it really isn't. And physically disconnecting the battery for a moment resets something in the controller so it starts functioning again upon reconnecting. Time to contact Furrion.

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    Quote Originally Posted by Ynot4me2 View Post
    FWIW for your investigation, even with the battery disconnect on, there's some what we have come to call parrisitic draw from things like the CO2 sensor that are always on. It's not much though.
    Understood. But as you say, it should be pretty minimal. As such, I would expect it wouldn't be a contributing factor for what I'm seeing. But certainly something to keep in mind.

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