# Watt values way different between Multiplus and Battery BMS

**URL:** <https://community.victronenergy.com/t/watt-values-way-different-between-multiplus-and-battery-bms/43294>\
**Category:** DIY\
**Tags:** multiplus-ii, diy\
**Created:** [15 August 2025 07:35 UTC](https://community.victronenergy.com/t/watt-values-way-different-between-multiplus-and-battery-bms/43294 "2025-08-15T07:35:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Pbeumer2001](https://avatars.discourse-cdn.com/v4/letter/p/46a35a/32.png) [@Pbeumer2001](https://community.victronenergy.com/u/Pbeumer2001)\
**Post date:** [15 August 2025 07:35 UTC](https://community.victronenergy.com/t/watt-values-way-different-between-multiplus-and-battery-bms/43294/1 "2025-08-15T07:35:20Z")

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Hi all,

I have a question about the values that my battery BMS and the Multiplus are showing. The amps and voltage are almost identical however the wattage is way off.

 ![image](https://europe1.discourse-cdn.com/victron/original/3X/5/5/55cdf560c8a6710b5bc1eb54d076146bd87eed5c.png)

In above screenshot we see that the voltage is 53.71/0 and the amps are 56.0/55.8. As long as I can remember wattage is calculated by voltage X Amps which means 53,7 \* 55,8 = 2996,46 watt. The BMS of the battery is almost right however the Multiplus is about 10% off…..

Any idea where this difference is coming from?

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**Author:** ![pwfarnell](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/pwfarnell/32/2341_2.png) [@pwfarnell](https://community.victronenergy.com/u/pwfarnell)\
**Post date:** [15 August 2025 08:08 UTC](https://community.victronenergy.com/t/watt-values-way-different-between-multiplus-and-battery-bms/43294/2 "2025-08-15T08:08:47Z")

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Answered on here several times, the W value in the Multiplus box is the ac power W, not the DC power W. 3355W ac into the Multiplus converts at 90% efficiency to 3000W DC. It is confusing.