question

Volker avatar image
Volker asked

battery capacity test using Multigrid-II ESS

Hello,

with a Multigrid-II running in an AC coupled on-grid ESS configuration, is/would it be possible to make a battery capacity test by

- asking the multi to stop doing the normal ESS work and
- asking the multi do e.g. a "charge => {0.1C / 0.2C} discharge => charge cycle"?

Thanks & Groeten - tullsta

Multiplus-IIbattery capacity
1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Phil Gavin avatar image Phil Gavin commented ·

Interesting concept and useful, I wouldn't have a clue do to deploy this through a Multi though.

It sort of relies on there being a dump load.

In practice, I have seen people use huge banks of electric fire elements, but direct on the batteries.

0 Likes 0 ·
3 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

This raises some other interesting control questions.

But to your core question, the current sensor in the multi is not test equipment accurate. It is perfectly functional, but it is not precise enough.

If you had a BMV....then maybe we get onto the questions of how to make it dump the battery capacity to the grid.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Volker avatar image
Volker answered ·

Hello Guy,

thanks for the fast reply. I know that the Multi is not (calibrated) equipment, but I thought that for most sanity checks this would be accurate enough.

In case one had a BMV :) would it then be possible to make a battery-dump / battery charge (i.e. control for const current/power discharge) or would this be a feature request for the Multi's FW? => just ordered a BMV700 anyhow

Thanks & kind regards - tullsta

2 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Peter Polz avatar image Peter Polz commented ·

In case of a BMV and Peukert correction over there is no need for a calibratete constant Check.. just disload and compare SOC to realstate

0 Likes 0 ·
Volker avatar image Volker Peter Polz commented ·

Hello Peter,

do I understand it right that the BMV then does the Peukert correction on the fly while integrating power? Guess this would be needed since there is not a constant load discharge guaranteed and all discharge would be related back to C20 then.

Sorry - new in this domain...

Thanks - tullsta

0 Likes 0 ·
boekel avatar image
boekel answered ·

I do this with a BMV and use the grid setpoint to discharge the batteries.

without a BMV a rough calculation will work, just count the time and current in VRM

2 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Volker avatar image Volker commented ·

thanks for the info!

regarding the "time and current counting" in VRM: what do I actually get when I export kWh from VRM as xls? Is this the same or is this something more elaborate?

kind regards - tullsta

0 Likes 0 ·

That’s smart.

0 Likes 0 ·

Related Resources