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bora avatar image

MPPT + Smart Chargers

When I run my generator with the smart chargers turned on and the solar in good sunlight I find I’m having to turn the solar off to the batteries in order to get the smart chargers to start putting out a decent charge current. Once they’ve settled I can switch the solar back on and it will sit in float while the smart chargers provide bulk.
Is there a way I can have all 3 (2x SC 1xMPPT) providing max power at the same time?

They are all connected to a VenusGX with VE.Direct/USB

MPPT - Solar Charge Controllersolarchargers
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You have solar mppt, and generator/grid chargers CHARGING your batteries at the same time??????

bora avatar image bora klim8skeptic ·

Yip

Still below the 128A that the 5x batteries could take.

1 Answer
snoobler avatar image
snoobler answered ·

Is this happening at the bulk/absorption voltage?


If so, your batteries can only take 128A BELOW the absorp voltage. You can't push any more current than that. Absorp is constant voltage, current limited. If all of your chargers together raise the voltage to absorp, you're at the max current allowed at that state of charge.

This sounds like exactly what you describe:

  1. Solar first, below absorp.
  2. Smart charger on limited, but voltage raised to absorp, no more current allowed
  3. Solar off, smart chargers increase current to achieve absorp
  4. Solar on, detects they can't flow programmed absorption termination current - go to float.


The only time you can accelerate charging with more current is in the bulk phase, i.e., below the absorption voltage.


Unless you're discharging your batteries to well under 80% SoC, you're not going to see dual charging as you expect. Your description sounds normal.


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