question

carsten2 avatar image
carsten2 asked

ESS with BMS battery, conditions for absorption, bulk, float

What are the conditions for the Multiplus II to change the bulk, absorption, float LED in a system with ESS, DVCC and a BMS battery?

What settings from the ESS assistent are still active and not disabled by DVCC or BMS?

What causes the Multiplus to switch of the charger when the battery is full?

In my system the bulk LED is almost always on. I observed short cycling around bullk and absorption, when the BMS reduces voltage to stop charging (CCL=0 doesn't work reliably). In rare cases I obsorved that all charging LED were off, but I am not able to figure out the conditions.


battery charging
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1 Answer
Alexandra avatar image
Alexandra answered ·

@carsten2

Bulk absorption and float are shown in the charger curve in the manual.

It switches from bulk to absorption once the battery is drawing under a certain number of amps trying to reach abtarget voltage. Stays in absorption for however long it is programmed to (at the target voltage) then drops to float. This usually has a few amps in and out evry now and then, depends on the battery.

In an ESS system, the MPPTs will stay in bulk so dont reflect the battery state.

The system since it is under BMS control will either says external control or be in whatever the battery dictates.

In DVCC the only thing that is ignored is CCL when you are feeding back to grid, otherwise everything else is adhered to.

It sounds like your battery is trying to balance. Dont forget also that there is some power assist as well with ESS so a bit of in and out is also to be expected.

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