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Michael Schmidt avatar image
Michael Schmidt asked

Multiplus II 48/5000 strange Behavior

Hi,


i have strange behavior of my multiplus II 48/5000.

I have a working configuration with Lifepo4 and CCGX and EM24.

in ESS i configured a 2channel BMS with aux in 1 and aux in 2 and configured Battery full if aux 1 closed

and also empty if aux 2 closed

so no bms is connected to both aux in and everything is fine!


now i finished working on my bms and changed in config aux 1 and two to open!


NOW the Multiplus still charges the battery but not discharges!?

i veryfied the correct pinout so if i open aux 1 #ESS3 is shown and if i open aux 2 #ESS4 is shown


so under normal conditions no #ESS failures are shown. But still no battery discharge!?!?


i veryfied this and changed back both aux to "closed" and removed the bms and

then multiplus is discharging battery.


Firmware is .465


best regards



Multiplus-II
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2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

@Michael Schmidt I've got a hunch...

What grid code are you using? does it by any change use aux1 as an input to disable feed-in? if so, de-select that option (at the grid code settings) and you should be good to go :)

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Michael Schmidt avatar image Michael Schmidt commented ·

Unbelivable this really was the fault :)

thanks for your help.



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Michael Schmidt avatar image
Michael Schmidt answered ·

Think I found the answer!

Q9: Why does my MultiGrid refuse to feed-in?



                  



                   

A MultiGrid system can enter a state where feed-in (more precisely: converting DC to AC while connected to the grid) is disabled.

This happens when, at the moment of connection to the grid, there is not enough DC power to perform the required relay test. (N.B. this relay test is part of the grid code specification - and is mandatory). In order to perform this test the Multigrid must be able to run from battery during a period of time (depending on the selected grid code but usually about 1 minute).

If this is not possible, the system enters a deadlock situation (if no precautions are taken) as it will not be allowed to connect to grid.

Therefore the following exception is made: When the device cannot perform the relay test, it still switches to grid but will not feed-in. Once a minimum amount of time has passed (about 15 minutes) and the battery voltage has risen to at least 14V (for a 12V system) the MultiGrid assumes that there will be enough DC power to run from the batteries and it will automatically switch to Invert, then perform the relay test, and switch back to grid. Only then feed-in will be enabled again.




                   

Therefore there is no need to worry - the system will resume feed-in automatically once the battery has been charged.


does anyone knows what is Minimum relay test voltage on MP II 48/5000?


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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @Michael Schmidt


It's on SOC level if you have CANbus bms:

firmware:xxxx464


Fix some ESS systems with lithium batteries not feeding back, which in certain situations happened when the system was (re)started while battery voltage was low or lithium system disconnected. In such situation, the Battery voltage was required to go above 14V / 28V / 56V for relay test to start and feedin to be re-enabled. Now, in such situation, the inverter/charger will also perform the relay test (and enable feed-in) when SOC above 20% rather than waiting for such high voltage that some batteries never reach.


but as you use non-canbus bms, you need to go above 56 volts - or perform a reset on the Multi :)

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Michael Schmidt avatar image Michael Schmidt Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hello Daniel,


i was on Firmware 465 and updated now on 466 but the same strange behavior.

I reset the multiplus but still the same!

in aux one and two open mode he will not feed in i dont understand!!

if i reconfig aux one and two to closed he will starts feeding in already seconds after grid test.



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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Michael Schmidt commented ·

I'm not sure I understand you correctly, you wrote:


i veryfied the correct pinout so if i open aux 1 #ESS3 is shown and if i open aux 2 #ESS4 is shown

are you saying#ESS3/4 doesn't effect feed-in?

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Michael Schmidt avatar image Michael Schmidt Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

i have for aux one and two two switching relays so i can use them as no (normal open and nc (normal closed)

#ESS3 and #ESS4 effect normal if i use closed in config for both aux.

after gridconnect multiplus starts feed in as desired.

if ess4 appears the multiplus feeds in if ess4 is cleared.

so everything works as designed


but if i use aux one and two as open (open will cause ess3 or 4) in config

the multiplus will not feed in! ESS3 and ESS4 are NOT shown or active.

but no feeding in ( charging works).



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