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Simon Glet avatar image
Simon Glet asked

ESS with 6 months of shore power and 6 months of boondocking

Hi,

I have a motorhome that is connected to shore power 6 months/year and boondocked (island mode) the rest of the year.

Now that I have shore power, the Cerbo GX runs ESS with DVCC. ESS is configured to keep my batteries charged so all the extra PV power is used to reduce the shore power usage. Very Nice! The campground meter does not support feed-in.

Next winter we will be back boondocking and the manual lists that as not an ESS use case.

My question is about how to enable/disable ESS without loading/unloading the ESS Assistant with the application VeConfig. There must be a setting combination. We have an onboard generator that we will run from time to time.

Thanks

Simon

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2 Answers
derrick thomas avatar image
derrick thomas answered ·

Unless something has changed recently, there is no setting to enable/disable ESS. The assistant must be installed or removed to enable or disable ESS.

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Simon Glet avatar image Simon Glet commented ·

On second thought I was wondering if, on the Cerbo GX, I set the AC input to Generator instead of Shore Power how does ESS manage that?

The Generator is not expected to run 24/7 right? When there is no AC input power, ESS could be dormant.

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Kevin Windrem avatar image
Kevin Windrem answered ·

Victron states that ESS must not be used for mobile applications (or any time the input of the Multi is connected to grid/shore power through a plug.

If you don't have an AC input connection the Multi is isolated from the grid. Some of the ESS logic might still function but any grid interaction will obviously not be possible. You'd want to set the system up so that no feed-in occurs. Many RV meters actually run the same direction whether the power is flowing to the RV or out of it!!

Again, use ESS in an RV at your own risk. There are safety issues.

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nickdb avatar image nickdb ♦♦ commented ·

This has always been an interesting topic. They don't explicitly say it is unsupported, just that it isn't a use case for ESS.

But ESS does many things, having it enabled provides a lot of capabilities.

Many fixed installs, mine included, intentionally disconnect from the grid to minimise power usage, so are effectively off-grid for extended periods and ESS works fine.

My thoughts are the assumption is that exporting is a major requirement, so being mobile or off-grid negates that, so why use ESS?

Many parts of the world cannot export anyway and the monitoring/control that ESS provides for a hybrid use-case is valuable.

You just have to be aware of how it works, any safety concerns and be prepared to manage that accordingly.

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delf67 avatar image delf67 nickdb ♦♦ commented ·
I thought the issue was more that with ESS enabled on a system connected via plug & sockets, it is possible the pins of the plug may remain live (albeit briefly) when the system is unplugged?
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nickdb avatar image nickdb ♦♦ delf67 commented ·
With LOM detection that really shouldn't be possible, dual contactors also eliminate that possibility under a failure condition.
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delf67 avatar image delf67 nickdb ♦♦ commented ·

From the ESS design & installation manual:

10.13. Q13: Can I use ESS in a vehicle or a boat? No, you cannot. After unplugging the shore cord it can take up a moment for the system to detect the loss of mains and open the back-feed relay. During those seconds, the shore power plug will be live: there is 110/230 Volts AC on the terminals. The exact number of seconds differs per country and depends on the local requirements. The same applies to other solutions where the wiring is not protected against accidental removing, for example a simple cable with end-user removable plug, such as a portable power supply.

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nickdb avatar image nickdb ♦♦ delf67 commented ·

That goes back to the being aware of the safety challenges. I wouldn't want to do this with a conventional domestic plug, If you choose to do this, then turning off power, before removing the plug would be prudent.

I certainly wouldn't just yank it out and hope for the best.

On local grid codes, I can't say there is a perceptible delay between power being removed and the relays opening.

But fair point. There is a lot of good detail that gets hidden in the depths of the FAQ's.

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Simon Glet avatar image Simon Glet nickdb ♦♦ commented ·

"so why use ESS"

I use ESS to reduce my power bill with solar when I have shore power for a long-term stay. ESS seems to be the only option to redirect your solar power to the AC loads and therefore less use the available grid. Campground meters usually do not support electricity feed-in.

ess-grid-support.png


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Kevin Windrem avatar image Kevin Windrem Simon Glet commented ·
The solar/wind priority mechanism is an alternative to ESS. It looks like you have that enabled (the icon in the battery).
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Simon Glet avatar image Simon Glet Kevin Windrem commented ·
Indeed but Solar was just taking care of the battery bank. When the batteries were charged, Solar power went to zero and the Multiplus was just using the Grid.
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