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desert-rat asked

Load Current

I have two Vectron MPPT 100-50 controllers connected to 1000 watts of solar and then to four 12 volt 170 ah lithium batteries.

When the controller goes into float mode it does not seem to be able to supply the existing load current. I still have plenty of solar power, but the batteries start to discharge for some reason. After an hour or two they are down to around 98%.

Thanks


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Alexandra avatar image Alexandra ♦ commented ·

@Desert Rat

Check your rebulk offset on the mppts.

Have you edited a Lithium profile preset when programmed for your batteries?

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desert-rat avatar image desert-rat Alexandra ♦ commented ·

Thanks for getting back to me so quickly!

Here are my settings:

Absorption 14.2

Float 13.5

Re-bulk voltage offset 0.01

I am currently in absorption mode and I am seeing very little current going into or out of the battery. So the controller is

supporting the load just fine.

I have good solar and a heavy 12 volt bus load.

Will let you known what happens when I go to float.


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snoobler avatar image snoobler commented ·
You say you have two Victron 100/50 connected to 1000W of solar. Please confirm that these controllers are connected to two separate arrays totalling 1000W and not connected to the same 1000W array.


Each MPPT must have its own array.

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desert-rat avatar image desert-rat snoobler commented ·
Yes, the controllers are on two separate arrays.
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snoobler avatar image snoobler desert-rat commented ·
13.5V float can allow for a small amount of battery draw, and if you have wiring losses between the MPPT and battery, it could make it worse.


I would change re-bulk to 0.2V


When in float, and you add a load, do you observe the MPPT to provide additional current to feed the loads?

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