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Jeff Kellner avatar image
Jeff Kellner asked

ESS will not work with generator

Hi,

I have an Onan 5500w connected to a MP2- which has power assist, my goal was to utilize the battery storage to reduce the fuel consumption of my generator. So I set up the ESS assistant, which works great when connected to shore power. As soon as I turn on the generator I am able to draw about 14 A from the generator once I exceed that it drops off the generator power and begins to invert fully and overload. I've tried everything I can think of, I tested the frequency of the generator checked the voltage etc. etc. If I delete the assistant the generator will load fully and work perfectly with power assist, the problem is as soon as the loads satisfy the charger begins to charge the batteries utilizing the generator which defeats the purpose of energy-saving/fuel saving at the generator.


Anyone have issues with the ESS assistant taking power from the generator? It doesn't like the feed from the generator, after a certain amperage. I've adjusted all the voltages and make sure that the generator was not dipping below the parameters for incoming power. I just don't understand why it works up to 14 or so amps soon as I have a second load it immediately drops the generator feed.

MP2

150/70mppt

GX with touch


Thank you,

ESSGeneratorAssistantspowerassist
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2 Answers
ceriw avatar image
ceriw answered ·

As you've said "shore power", I assume that this is a mobile system of some kind (boat/ camper etc).

If this is the case, as per the guidance on here, ESS is not to be used.

ESS will not work with power assist well with a generator, it will end up either overloading or disconnecting from the generator, unless the generator is capable of outputting significantly more power than the Multi in the system.

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Jeff Kellner avatar image Jeff Kellner commented ·

@ceriw Yes, this is an RV, with an onan 5500W Gen, I was using power assist to supplement the generator power and by reducing the current limit coming from the generator to save fuel. It seemed to work well until my loads dropped off and the batteries immediately started to charge which then consumed unnecessary fuel from the generator.

So, the generator and the inverter would run simultaneously when the load was greater than the amperage set point.


Is there any way to accomplish my objective? I don't have a large fuel source for my generator and I have stored energy in the battery so I would like to consume that as well as supplemented with the generator when the load requires it and still have the ability for the MPPT to charge the battery just not use the generator to charge the battery. I am not always on the gen I need to switch back to normal operation from the touchscreen or automatically. Thank you for the help.


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Jeff Kellner avatar image Jeff Kellner commented ·

@ceriw Yes, this is an RV, with an onan 5500W Gen, I was using power assist to supplement the generator power and by reducing the current limit coming from the generator to save fuel. It seemed to work well until my loads dropped off and the batteries immediately started to charge which then consumed unnecessary fuel from the generator.

So, the generator and the inverter would run simultaneously when the load was greater than the amperage set point.


Is there any way to accomplish my objective? I don't have a large fuel source for my generator and I have stored energy in the battery so I would like to consume that as well as supplemented with the generator when the load requires it and still have the ability for the MPPT to charge the battery just not use the generator to charge the battery. I am not always on the gen I need to switch back to normal operation from the touchscreen or automatically. Thank you for the help.


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popnic avatar image
popnic answered ·

@Jeff Kellner

There is hope...

I have an ESS assistant set on MP2 48V 5k in an experimental installation.

Have no issues using a small Honda EU 22i inverter generator connected at ACin1 except disabling the LOM.

Grid:

GX device Remote Console- Settings>System Setup>AC input1 = Grid ESS is working just fine. Power from battery is added to the power from grid if is necessary and MP2 will feed the grid with surplus energy if is set so.

Generator:

GX device Remote Console- Settings>System Setup>AC input1 = Generator

The generator power taken by MP2 is as per current limit settings:

Multiplus II >Input Current Limit and supply the load and with the remaining power it charge the battery.

If the load is higher than the generator power, MP2 will use energy from battery in addition to power the load.

ESS has a kind of power assist in generator mode also.

I test the system in generator mode with a load of 2kw switching on and off and no issue while SOC <90% . BTW the batteries are LFP 230Ah.

This is a typical application for Quattro but I am happy to see that I can switch from grid to generator in remote control and I can use MP2. Even PV inverter on ACout works just fine in generator mode.

Only issue is that without LOM and I have to use an additional protective device for grid connection.

Good job Victron!


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