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johnsmith avatar image
johnsmith asked

Multi Plus II AC out 60-80W higher incorrect readings in VRM

Multiplus II AC out 60-80W higher incorrect readings

Having a strange thing happening recently.


The Multiplus II 48/3000 is showing abnormal AC readings approx. 50-80W higher than the actual power output on Critical loads when inverting.


When on passthrough the AC reading is correct.

You can see in the attached screenshot when inverting that the maths are wrong.

The pylontech is showing the correct load in W, the Multiplus II is reading over by 50W.


Is this a communication problem with pylontech causing the issue?

DVCC is set on and pylontech is controlling the charging.

Any ideas?

1679832056539.png

Multiplus-II
1679832056539.png (89.5 KiB)
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2 Answers
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Jason - UK answered ·

@Johnsmith do you have a shunt you can take a reading from between the batteries and the Multiplus? Normally would would see 10% lower reading on the AC loads when inverting, which is the losses when changing from DC to AC.

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johnsmith answered ·

This behaviour has only started since we swapped over to Pylontechs from AGM. All the same appliances are running as before but showing a higher AC output than before. I'm wondering whether it's a BMS firmware bug in the Pylontech. I will put a smart shunt between the battery and the Bus to see if there is a difference but it still doesn't explain the output AC reading higher than before.

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