# Multiplus ii hum while charging

**URL:** <https://community.victronenergy.com/t/multiplus-ii-hum-while-charging/25386>\
**Category:** DIY\
**Tags:** multiplus-ii, diy, ess\
**Created:** [16 March 2025 13:48 UTC](https://community.victronenergy.com/t/multiplus-ii-hum-while-charging/25386 "2025-03-16T13:48:40Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Pieter](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Pieter](https://community.victronenergy.com/u/Pieter)\
**Post date:** [16 March 2025 13:48 UTC](https://community.victronenergy.com/t/multiplus-ii-hum-while-charging/25386/1 "2025-03-16T13:48:40Z")

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Is this a normal humm when the fan is running in the mp and it is charging at 60 amps?  
The load on ups out is minimal.  
I think it is ok but not shure.

  
Thanks.

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**Author:** ![alexpescaru](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/alexpescaru/32/270_2.png) [@alexpescaru](https://community.victronenergy.com/u/alexpescaru)\
**Post date:** [16 March 2025 13:58 UTC](https://community.victronenergy.com/t/multiplus-ii-hum-while-charging/25386/2 "2025-03-16T13:58:35Z")

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It’s normal for this inverter topology.  
It will be less or almost nonexistent if the case was from an non ferrous material like aluminium, but hey, money, money, money… 🙂

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**Author:** ![Pieter](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Pieter](https://community.victronenergy.com/u/Pieter)\
**Post date:** [16 March 2025 14:49 UTC](https://community.victronenergy.com/t/multiplus-ii-hum-while-charging/25386/3 "2025-03-16T14:49:18Z")

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Hee, thanks.  
The MP is in the barn so in the house i can’t hear it. Was just wandering if my fan is starting to fail or so, but i think i would get an overtemperature warning in that case  
Thanks for the reaction.

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**Author:** ![alexpescaru](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/alexpescaru/32/270_2.png) [@alexpescaru](https://community.victronenergy.com/u/alexpescaru)\
**Post date:** [16 March 2025 14:52 UTC](https://community.victronenergy.com/t/multiplus-ii-hum-while-charging/25386/4 "2025-03-16T14:52:23Z")

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No problem, what I was trying to say is that most of the hum is because of the big transformer under load resonating in that big metal cage… 🙂