hastilyfabricated avatar image
hastilyfabricated asked

MPPT + Orion DC-DC = problems for directly wired loads?

Hello, all and thanks for all the helpful information I've gleaned thus far from this forum.

Context would be sailboat where previously 200W solar MPPT controlled to 12V AGM house bank entirely isolated from 12V AGM engine start battery which was charged exclusively by the alternator. Then we had three weeks of cloudy weather on our last trip.

So now have an Orion TR12/12-30 to allow the alternator to charge both the start (with priority there) and then also the house.

What remains (forgive my ignorance here) is a basic electrical engineering question: while my house panel loads are connected to and regulated by the MPPT load output (less than 15 amps altogether) there are higher amperage loads (inverter, fridge, and then bilge pumps that I never want cut out by MPPT) directly connected to the house bank by a separate fuse box. With the Orion charging output maxing at 40 amps to the house bank, what keeps all that current from frying the loads downstream? All are fused appropriately, just want to learn something here--does the battery itself act as an effective buffer to absorb that current? Is the bilge pump going to be fine because it's going to draw only what it needs in terms of amperage and as long as the voltage is regulated appropriately nothing gets fried?

Appreciate the help and again, please forgive my ongoing learning process here.

MPPT Controllersorion dc-dc
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1 Answer
mvas avatar image
mvas answered ·

Your loads draw only the amperage they need. They are not affected by any amperage your MPPT Charge Controller or DC-to-DC Charger is pushing into the House Battery.

If your car engine was running during a fill-up, would your engine start running faster just because you are pumping gallons of gasoline into the tank? No, the car engine does not care how fast you fill your gas tank.

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