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mattplowman avatar image
mattplowman asked

MPPT 75/15 - Charger Enabled Setting?

From the MPPT manual - "This setting Enables or disables the battery charger. It is by default set to "enabled". This setting can be used when work needs to be carried out on the installation. When this setting is disabled, the batteries will not be charged"


I have a couple of questions:

Where does the power from the PVs go when set to disabled? Are there dump resistors in the MPPT?

Can I use this feature instead of a physical on / off switch? In my nearly complete install I have fuses between MPPT and Controller and am in the middle of deciding if I want an on/off switch or breaker between MPPT and PV. If this feature in the app does the same thing safely and reliably then I will not bother with a physical switch. Specifically I want to be able to turn off the charging current to the battery once full and when I leave the boat so I do not have unwanted charge cycles on the batteries when the boat is not in use.

battery chargingMPPT SmartSolar
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1 Answer
Mike Dorsett avatar image
Mike Dorsett answered ·

When the charger is 'disabled' there is no current drawn form the PV input. PV will rise to VOC and the panels cease generating power - despite being in full sun or otherwise. Dump resistors are not needed.

You could use this feature to disable charging when you leave the boat, BUT a physical isolation switch between the PV and the MPPT is a regulatory requirement and a very good thing to have. This should not be omitted from a design.

Personally I would leave the charger on - float charging the batteries to take care of any self discharge.

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mattplowman avatar image mattplowman commented ·
Thank you , much appreciated.
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