question

markde avatar image
markde asked

ESS discharge only down to 40.7 volts

Hi at all,


my ESS Sytem with Multiplus-II 3000 discharge only down to 40.7 volts. But I would like to go down to 38 volts. The Hardware of the Multiplus-II should be able to do so. I guess it’s just a Software/Firmware limitation. But why? Any Chance that VICTRON will change this?

ESSfirmware updatedischarge level
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markde avatar image markde commented ·

I need Help Please.

Can someone explain to me why there is this discharge voltage limit in ESS mode. I dont understand why. because in off grid mode there is no limit at 40.6V


Any chance to make a Modification to ESS Assist?


thanks!

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2 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

hi Mark, below that voltage, the hardware isn’t able to feed power into / add power onto / an existing AC supply.


so. The minimum voltage for ess operation is slightly above minimum voltage for offgrid inverter operation.


this can’t be improved I’m afraid, otherwise we would have done it already.



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Jason - UK avatar image Jason - UK commented ·
@mvader (Victron Energy) as an idea, could a voltage optimiser be used to bring the supply voltage on the AC-in down to 220v to allow the inverter to operate the batteries down to a lower voltage below 40.6? Would this make any difference?


The reason I ask is my supply voltage is between 248v and 253v and I have considered a voltage optimiser before because of of other issues in the house like premature failure of the heating elements in the oven, the vacuum cleaner over heating after prolonged use and so on. I have also thought about a voltage optimiser to see if it improves the performance of the solar inverter and also the Multiplus.

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Jason - UK commented ·
That might help a bit, but: first check if you really gain much from this. there is very little energy left in the battery below these voltages.
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raphael303 avatar image
raphael303 answered ·

I have made this a new topic here: https://community.victronenergy.com/questions/170674/why-is-there-the-406v-discharge-limit-how-to-remov.html?childToView=170701#answer-170701

Also I hope to get a full and updated statement of victron on this. Because imho this is a significant and non-communicated limitation of the multiplus-II. To me this forum post being the only place with this infomation is bordering on scandalous. This HAS to get into the spec-sheet. And the manual of course, at the very very least.

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nickdb avatar image nickdb ♦♦ commented ·
I have passed this along to the powers that be for consideration.
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Hi @Raphael303

What exactly is the problem with this? what battery are you using that has capacity below 40 volts?

PS I use 12S li-ion batteries quite a lot, and when ESS stops pushing power from the battery, and I switch to inverter mode, there is almost no capacity left.

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