EG4 Generator Boost - AC output power limited to inverter value?

[BlackOilCoder]

Apologies for a double post on this, but I can't tell if "off grid" or "all-in one" is the best place for this question.

I'm looking to build an inverter system designed to boost my F150 PowerBoost (hybrid) with a 7200W generator. I'm currently running this setup at my house via a 3-wire neutral switching transfer switch. It's actually been active since last Thursday night due to the unexpected tornado/derecho that de-wrecko'ed the place.

Obviously my 7200W generator will not start my 3Ton downstairs unit. I have a Hyper Engineering SureStart coming, but I seriously doubt that even with that in place it will start.

What I'd like to have is an inverter setup that allows generator boost capabilities to handle surges and to provide limited support for continuous demand beyond the generator capacity. An analysis of my last summer's usage (based on 15 min kwh update from my meter available online), indicates that I should be able to get there with only 100Ah.

I'm looking for a reasonably priced system here as it's for emergencies only. I've considered something like the Sigineer (and other similar Chinese units) 6000W unit that handles surges up to 18,000W for 20 seconds; however, these units perform a switch over in (supposedly) 6 to 10 milliseconds. I don't really know how that would effect a motor starter, but I suspect it would not be amazing. Additionally, I prefer to have listed equipment handling power loads like this in my house.

I really like the Victron Multi-Plus power assist feature as I've seen lots of information that the function is able to ADD to the total available output power up to the AC Bypass limit. That said, I'd have to buy 2 x 10,000VA units to achieve what I want.

Notionally, if the EG4 6000XP works in a similar way and works ADDITIVELY to the generator capacity, it would likely be perfect for my needs. Also cheaper and purpose designed for the US split phase 60Hz market. I can not find this information however. I sent EG4 a tech support request, but I don't know if the web form is truly monitored or not and this group seems to have the most knowledge on the subject around the internet.

I would consider other units as well if I'm missing some besides the Victron and EG4 with true generator boost, I'd like to know. If anyone as used the Chinese 6000W inverters successfully to handle surge loads, that would be good info as well, but honestly for the price, the EG4 6000XP offers way more for the money assuming it can work how I need.

 

[sunshine_eggo]

I can attest to the Sigineer's brutal surge capability. We installed a 24V/6000W split phase model at my neighbor's to start his 700' deep 3hp Grundfos well pump. Run power was 4000W, and it started it like it was nothing (not an SQ pump).

I called SS and spoke with "Dakota." He was not confident that the unit would supplement LIKE Victron PowerAssist, i.e., Victron PowerAssist is completely additive. Example:

4000W genny
5000W MP-II

Pull an 8000W load, and you'll get 4000W from Genny and 4000W from the MP-II (not so black and white, but idealized for discussion purposes), and it will maintain this for as long as the battery can support it.

According to Dakota, boosted output is limited to the total output of the 6000XP, i.e., it's not additive - you're limited to the inverter's continuous and surge ratings, so in the same example above, you would only get the 8000W for as long as the inverter can normally support that overload.

Dakota's delivery did not fill me with confidence. @EG4_Jared can you clarify how generator boost works, and its limitations?

 

[BlackOilCoder]

I can attest to the Sigineer's brutal surge capability. We installed a 24V/6000W split phase model at my neighbor's to start his 700' deep 3hp Grundfos well pump. Run power was 4000W, and it started it like it was nothing (not an SQ pump).

I called SS and spoke with "Dakota." He was not confident that the unit would supplement LIKE Victron PowerAssist, i.e., Victron PowerAssist is completely additive. Example:

4000W genny
5000W MP-II

Pull an 8000W load, and you'll get 4000W from Genny and 4000W from the MP-II (not so black and white, but idealized for discussion purposes), and it will maintain this for as long as the battery can support it.

According to Dakota, boosted output is limited to the total output of the 6000XP, i.e., it's not additive - you're limited to the inverter's continuous and surge ratings, so in the same example above, you would only get the 8000W for as long as the inverter can normally support that overload.

Dakota's delivery did not fill me with confidence. @EG4_Jared can you clarify how generator boost works, and its limitations?

Thanks for the details.

For my use, I suspect I could use a more basic inverter charger. I’m just using the inverter and batts as surge capacity. Ideally I’d like to have my inverter generator powering the main load only being supplemented with the inverter. But for emergency use, I guess using inverter priority could work. I may need more batteries to supply the surge load however.

I’ll be good to hear from EG4 on how it actually works though.

 

[EG4_Jared]

I can attest to the Sigineer's brutal surge capability. We installed a 24V/6000W split phase model at my neighbor's to start his 700' deep 3hp Grundfos well pump. Run power was 4000W, and it started it like it was nothing (not an SQ pump).

I called SS and spoke with "Dakota." He was not confident that the unit would supplement LIKE Victron PowerAssist, i.e., Victron PowerAssist is completely additive. Example:

4000W genny
5000W MP-II

Pull an 8000W load, and you'll get 4000W from Genny and 4000W from the MP-II (not so black and white, but idealized for discussion purposes), and it will maintain this for as long as the battery can support it.

According to Dakota, boosted output is limited to the total output of the 6000XP, i.e., it's not additive - you're limited to the inverter's continuous and surge ratings, so in the same example above, you would only get the 8000W for as long as the inverter can normally support that overload.

Dakota's delivery did not fill me with confidence. @EG4_Jared can you clarify how generator boost works, and its limitations?

You would be limited to the total output and surge rating of the 6000XP.

The principles of the GEN Boost are as follows:

1. If Max Gen Input Power is greater than or equal to Load Power:

The generator's power will be given priority to satisfy the load demand. If the generator has excess power and the PV power is not in excess, the generator will charge the battery.

The hierarchy for charging power sources is: PV power takes precedence over Generator power.

2. If Max Gen Input Power is less than Load Power:

The inverter will switch to Gen Boost mode. PV and battery will discharge to cover the loads that the generator cannot support.

The battery will discharge until the SOC/Voltage is less than or equal to the Off-Grid EOD Voltage/SOC (Discharge Cut-off Voltage/SOC).

The order of priority for power when meeting load demands would be that Generator power is prioritized over PV power, which is in turn prioritized over Battery discharge power.

 

[sunshine_eggo]

Thanks for seemingly detailed response. Unfortunately, It's still not clear to me.

Does it work like Victron PowerAssist, i.e., does the inverter "boost" the generator power by adding inverter power to it, i.e., passing through the generator power to loads AND boosting it?

Steady state scenario (assuming balanced legs):

No PV (night time).​

80% battery SoC (high enough to not trigger any events).​

3500W generator.​

2500W charging.​

1000W passed through to loads.​

Loads increase to 5000W.

How is the 5000W load met, and by what equipment in what proportion?

 

[BlackOilCoder]

You would be limited to the total output and surge rating of the 6000XP.

I appreciate the input.

Just to clarify, for the 6000XP the AC input max continuous current is 37.5A (9000W).

The inverter continuous AC inverter output is 25A (6000W).

So the max continuous AC output of a 6000XP running in gen boost mode is 9000W + 6000W = 15000W?

Or are we still limited to the max continuous AC output of 9000W?

What about surge capacity (short term 1 second max)? Is that the AC bypass limit of 50A (12000W) + 8000W of the inverter for 20,000W?

 

[BlackOilCoder]

Thanks for seemingly detailed response. Unfortunately, It's still not clear to me.

Does it work like Victron PowerAssist, i.e., does the inverter "boost" the generator power by adding inverter power to it, i.e., passing through the generator power to loads AND boosting it?

Steady state scenario (assuming balanced legs):

No PV (night time).​

80% battery SoC (high enough to not trigger any events).​

3500W generator.​

2500W charging.​

1000W passed through to loads.​

Loads increase to 5000W.

How is the 5000W load met, and by what equipment in what proportion?

My understanding is that the gen boost mode is really for two configurations:

1. PV backup - where the unit calls for a gen start based on SOC and while running in that charging mode all load (up to the programmed generator max) is provided by the generator with any load above the generator max being sourced from the batteries (assuming SOC allows).

2. Generator Support - This is my use case. No PV system and just using the inverter to provide capacity above that of the generator maximum and the generator to charge the batteries when the load is less than the programmed generator max.

For your specific case above, I believe what would happen when load increases to 5000W, 3500W would come from the generator, 1500W would come from the batteries and no charging until the SOC no longer allows battery use when you would likely trip on overload if the 5000W of load still existed.

All that makes sense to me, but I still don't understand the maximum capacities of the system as stated in my post above. I'm hopeful @EG4_Jared will come back with the limits as 9000W continuous and at least 12000W surge. It would be amazing if the surge was 20kw, but I doubt that's how it works.

 

[EG4_Jared]

Thanks for seemingly detailed response. Unfortunately, It's still not clear to me.

Does it work like Victron PowerAssist, i.e., does the inverter "boost" the generator power by adding inverter power to it, i.e., passing through the generator power to loads AND boosting it?

Steady state scenario (assuming balanced legs):

No PV (night time).​

80% battery SoC (high enough to not trigger any events).​

3500W generator.​

2500W charging.​

1000W passed through to loads.​

Loads increase to 5000W.

How is the 5000W load met, and by what equipment in what proportion?

The inverter would utilize the GEN Boost with 3500W coming from the generator and the remaining 1500W discharging from the battery bank.

 

[EG4_Jared]

I appreciate the input.

Just to clarify, for the 6000XP the AC input max continuous current is 37.5A (9000W).

The inverter continuous AC inverter output is 25A (6000W).

So the max continuous AC output of a 6000XP running in gen boost mode is 9000W + 6000W = 15000W?

Or are we still limited to the max continuous AC output of 9000W?

What about surge capacity (short term 1 second max)? Is that the AC bypass limit of 50A (12000W) + 8000W of the inverter for 20,000W?

The AC output would still be a continuous 6000W with a surge capacity of 12,000W for ≈3.5 seconds | 11,000W for ≈5 seconds with GEN Boost enabled.