Does MPPT 100/20 load output allow bidirectional current (from AC charger)

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smbnnt asked Dec 20, '19

Does MPPT 100/20 load output allow bidirectional current (from AC charger)

Hi,

I have a solar array in my rv charging a deep cycle battety through a smartSolar 100/20 charge controller. I also have a Progressive Dynamics PD4000 battery charger/power distribution block installed. I would like to use the load output to avoid over-discharge of my battery. However, I also would like to be able to use the PD4000 to charge the battery when AC power is available. My question is, can I connect the load output of the charge controller to the battery terminals of the PD4000? Under normal operation current will flow from the load output to the DC distribution block of the PD4000 and on to the various load circuits. When connected to AC power, current could flow in both directions, from the PD4000 charger to the battery through the load output or from the battery to the load. Can I do this or do I need to use the load output to control a relay/SSR connecting the battery to the PD4000?

MPPT Controllers battery charging AGM Battery discharge level

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Answer 1 · 2019-12-20T23:05:40Z

Justin Cook answered · Dec 20, 2019 at 11:05 PM

@smbnnt, the load outputs are outputs only, they cannot be used for inputs.

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Answer 2 · 2019-12-21T00:06:18Z

Matthias Lange - DE answered · Dec 21, 2019 at 12:06 AM

The MPPT 100/20 can only give you 20A for loads so I think you couldn't use it for that.

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Answer 3 · 2020-01-10T20:06:05Z

markcx answered · Jan 10, 2020 at 08:06 PM

If I understand you correctly, you want things to work in a similar way to how things work on my boat.

I have a battery charger permanently connected to the battery in the usual way and the solar charge controller connected to the panels and battery. No loads are connected directly to the battery, all loads come from the load output of the charge controller.

This works fine for me because my current requirements are modest - below the maximum load output of the controller (if your needs are higher, a relay would be the way to go).

When the charger is powered, the battery charges and I'm still able to use everything as normal. When not charging, everything works until the battery voltage drops below the threshold I've set, then shuts down. When there's a high enough battery voltage, whether from solar controller or charger, everything's back on again.

Works great.

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