Sustain current too high?

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jorge-folgado asked Apr 22, '20

Sustain current too high?

Hello Victron fellows,

I have set some Li ion with Victron inverters, always for self consumption with PV inverters, but this one is cracking me up. This system consists in three 48V Multiplus II 3000/35 as a three phasic system, and an ESS assistant is set. The sustain voltage is 43V and cuttoff around 42V. The modules have a low SOH, but the system should work anyway. It charges and discharges correctly, up to the point where my BMS disables allow to discharge at around 48V, because there are low cells (it should discharge to less than 42V if it was good).

Then, Sustain mode is active and the current goes UP TO 90A. Of course when this happens the voltage raises quickly, the allow to discharge comes on again and it goes to Discharging mode. Repeating the process endlessly - Even without PV POWER, that means it consumes a lot of power.

My question is, why does it go up to 90A, since sustain mode should be 5A per unit and how can I solve this?

Thank you very much!

Multiplus-II ESS charge current limit current limit

2 |3000

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Answer 1 · 2020-04-22T21:47:45Z

Daniël Boekel (Victron Energy Staff) answered · Apr 22, 2020 at 09:47 PM

Hi @Jorge Folgado

I've sent you an email, we'd like to look in to this.

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Answer 2 · 2020-07-30T10:51:21Z

diego quintero answered · Jul 30, 2020 at 10:51 AM

I Have a similar problem, can you provide some guide?

I connected the batteries switch on Multiplus Victron, I have installed ESS too and then 15Amps was putted in the system, when I only allow 3 max in the configuration. In my system this can damage my batteries. After 10 min I switch everything off, because sustain mode was present and could not have control with ESS grid set point.

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Answer 3 · 2021-09-15T09:56:53Z

sedlons answered · Sep 15, 2021 at 09:56 AM

Same problem here.

I have 3pcs of Multiplus 5000 48V with ESS and two wire BMS. Sustain voltage configured to 40V.

Around 47V is disabled discharge allow and immediately start charging with current > 80A. Sustain mode is left after pack voltage is over 50V.

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Answer 4 · 2021-10-14T11:02:54Z

hjb answered · Oct 14, 2021 at 11:02 AM

same problem here.

i use multiplus 2 GX with a ESS and configure the 2 channel BMS.

when the bms give the signal UVP, the multi begins to load with the max current. and it will never stop.

thats a proplem. is there any solution for this? i would, that the Multi go to the sustain Voltage with a max. 5 Ampere current and stop the charching at the sustain voltage level. Or go return to the normal use, when the UVP signal is loss.

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