question

cstenger avatar image
cstenger asked

MPPT Load output disabled on MPPT being disabled?

Well, the title already describes it. Is the load output of a 75/10 being disabled when the entire MPPT is being disabled?

In particular:

  • The load output will feed a trickle charger hooked up to the main battery to maintain it.
  • Not to kill the trickle charger while cranking the engine, I want to switch it off.
  • Therefore, I want to switch off the MPPT using the RX port and ignition signal.


MPPT Controllerscharger
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1 Answer
kevgermany avatar image
kevgermany answered ·

Not sure which trickle charger, but a brief drop in voltage at engine start shouldn't kill it, mine has survived being permanently on for nearly a year now.

Off should mean off for the MPPT.


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cstenger avatar image cstenger commented ·

A Votronic 3065. The voltage drop would happen on the output side, so irrelevant from my standpoint.

But, would MPPT off mean MPPT Load output off as well? If so, I doesn't matter how the Votronic behaves ..

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kevgermany avatar image kevgermany ♦♦ cstenger commented ·

That's what I have. I opened it up a while ago. There are a couple of diodes, resistor and what looks like a temperature dependant resistor. All that will happen is that the current goes up, limited by the internal circuit. They're limited to about three amps.

Should be safe.

But load output should be off if you turn the MPPT off. But the votronic will draw from your house battery. Not sure how quickly the voltage drops after the MPPT is turned off. So there may be some current.


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cstenger avatar image cstenger kevgermany ♦♦ commented ·

If there's an internal limitation that'd be good, cause otherwise it'd blow the fuses anyways (5m wire to the engine bay).


Load off on MPPT off would be double safe. As I do not let it crank right away, but wait 1-2 secs (immobilizer and other electronics checks) it should work.

On the other hand: as the MPPT is being switch off, and the voltage drops, the "algorithm" threshold will kick in switching the load off.

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