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freddyuk avatar image
freddyuk asked

Aquion charging at different charge current limits in ESS

I seem to be the only poster with Aquion batteries. I am realising the very best way to deal with charging parameters as I experiment. I am on ESS so grid connected.

I have now changed over to a night /day tariff so all my grid power is night time rate. This is working very well as no grid import in day time even in winter.

My Aquions need a slow charge rate so I limit the charge amps to give me say 2kw and they are charged up each night (8 hours max.) using scheduled charging. This means they can be charged to 100% in only 3 hours if SOC is high but easily fully charged if starting SOC is lower.

Now I want to have a higher charge limit (or no limit) for solar charging via inverter to maximise solar input as this can be intermittant in winter but is there a way to have 2kw charge limit in scheduled charging at night and a higher charge limit (or no limit) in daytime outside scheduled window? I have no DC system of course.

Thanks

charge current limit
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boekel avatar image boekel ♦ commented ·

That would be an nice feature (setting a charge limit during scheduled charging).
I don't know of a way to do that now.

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wkirby avatar image wkirby ♦♦ commented ·

It depends upon where your PV is injecting enery (AC-IN or AC-OUT) but what about limiting the AC-IN (grid) current to say 8A (~2KW)? That way the grid supplied energy will be limited to ~2KW and if your PV is on AC-OUT then that will only be limited by the DC current setting in the charger settings tab. If PV is on AC-IN, then of course my idea is rubbish becuase it will also be limited to ~2KW.
Just an idea.

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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi Freddy,

I came extremely close to buying some Aquion batteries myself.

As Boekel said, there is no GUI feature that does what you are asking. However it is all a matter of control, and it is absolutely technically possible. Depending on your level of interest, you may wish to dig a bit deeper into the options available to customise and modify Victron equipment.

Some potential leads to get you started on how you may be able to do something like you are asking are here:

https://github.com/victronenergy/node-red-contrib-victron

https://nodered.org

https://github.com/victronenergy/node-red-contrib-victron/blob/master/documentation/specification.md

The community is an excellent place to begin to discuss and explore this, as you can not get support from Victron directly (though we would also LOVE to hear about what you learn).

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freddyuk avatar image
freddyuk answered ·

Thank you I will go deeper! All results will be posted.

Guy, if only Aquion had priced their batteries against Lead Acid instead of Lithium they may have survived and be developing much more efficient units. I am delighted with mine as I have no worries about gas or topping up or fire risks etc. In my domestic scenario they work very well and we have not taken dramatic steps to reduce loads just to see how they perform in the real world. My wife still has a tumble dryer! I have a generator ready to connect up but wanted to see what recharging loads I would need to cover with diesel costs. I can easily see now what grid import I need to replace with generator.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

I have my own armchair philosophical theories on their demise.

I think fundamentally though they needed a backer with techno-futurist-environmental values and deep pockets. And I bet that persons capital is in great demand.

From a business operators point of view, each time I came close to placing an order, the next generation was so close as to make the previous one redundant. And there were serious technical issue with the early versions, high internal resistance and very low voltage at low states of charge that made complete cycling impossible.

On top of power density and price issues.

I do still believe they had a market, and a product that owned a niche that is big enough to build a business in. It's a sad story and the off grid energy world is poorer for their bankruptcy.


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