Honda genset ramping up in eco mode - issue?

nyoffgrid

Hey all,

I have a small off grid cabin. I have a regular circuit breaker panel inside that is fed by my battery & inverter charger system. At night I plug in my generator directly to the inverter charger which then let's the cabin (friege, ac, lights, and so on) run off the genset while also charging my battery. My genset is a Honda inverter 2200watt. 

The things is... When eco mode is turned on in this genset it, in case someone here doesn't know, lowers the rpm until an appliance "calls" for more power - it than quickly ramps up to deliver more power. My issue (been like this for 10+ years) is that when the fridge (or ac) kicks in - the required ramp up is very large for the generator so for a split second the lights and all other appliances will flicker as they lose power. So things will turn off and on and some will stay on but it cusses this short drop in power.

I always thought this is just the way it is.. 

But I wonder if there is a device that I can buy / install that will fix this?

BB.

It is sort of the "draw back" of gensets that support "ECO Mode" throttle. But they are more fuel efficient, and usually quieter than the "standard" fixed RPM gensts.

I have a couple of Honda eu2000i (older version) and the "lag" in the engine RPM to run up the RPM to support higher output power can cause the "flicker problem" or possibly reboot a computer / TV set / etc. If I have a higher base load on the genset (fan, lighting, air/water pumps for fish pond, etc.), then the starting load from a refrigerator does drop the AC voltage as much.

Yamaha used to make a genset with "Boost"--As I recall it had a battery that was "in parallel" with the genset output and would reduce the voltage drop when in ECO Mode... But, from what I can find, it looks like Yamaha no longer makes that model.

So, we are now looking at a UPS (Uninterruptible Power Supply). Basically, plug the UPS into the Genset AC output, and your "sensitive loads" (TV, computer, etc.) into the UPS 120 VAC output.

For examples of UPS systems (not recommending the website--Just a place to start your search):

https://www.pcguide.com/psu/guide/best-uninterruptible-power-supplies/

Costco UPS example:

https://www.costco.com/cyberpower-1350va810watts-simulated-sine-wave-ups-battery-backup-with-surge-protection.product.100845557.html

A UPS takes the 120 VAC input, charges a smallish (typically 12 volt for smaller UPS's) battery pack, then the inverter takes the 12 volt (or whatever) battery voltage and converts it to 120 VAC...

The UPS will supply (reasonably) stable 120 VAC to your "sensitive loads" when the Genset AC voltage sags during refrigerator starts....

Unfortunately, the "UPS" is a "complicated" subject. There are continuous conversation (as I described above AC=>Battery=>AC inverter ), or those that switch over when the AC mains fail... The continuous conversation is "most stable" but less efficient AC power usage than the fail over type... Some have AC voltage regulation (I.e., can take 100 VAC-140 VAC and convert to 120 VAC stable voltage with a transformer)...

Some are pure sine wave, others are modified square wave (no idea what "simulated sine wave" is).... PSW/TSW (pure/true sine wave) is ideal... MSW is less idea).

Depending on what your sensitive loads are, at $130-$200--Cheap enough to give it a try(?).

Batteries typically last 1-2 years in UPS systems. And usually are pretty happy with "glitchy" Genset outputs. Most small computer UPS systems have a small battery bank and may carry rated load for a few minutes to 10-20 minutes (small UPS systems are intended to run a computer just long enough to save your work and safely shutdown the computer).

If you are interested more in Generators, Sine Wave, Modified Square Wave, and such, a very good web site for Movie/Grip genset 101:

https://www.screenlightandgrip.com/html/emailnewsletter_generators.html

This is a "quick and dirty" solution...

A question about your existing solar power system... Are you powering 120 VAC from Genset (when Genset is running) and from solar system's AC inverter when not?... Could you power your (at least your sensitive) loads from the AC inverter, and the other loads (fridge, water pump, etc.) from the Genset?

The inverter-charger may not be doing a "good job" of stabilizing the EU2200i output voltage (inverter-chargers may not "switch to battery mode" as fast as a UPS will (which should switch in 8 milliseconds or 1/2 of an AC sine wave cycle).

An option would be to purchase a second AC inverter only and power it from your solar battery bank to power LED lightning, TV, etc....

Our host has lots of inverters:

https://www.solar-electric.com/search/?q=inverter (sort from low to high costs to find "small" inverters)

Depending on your loads -- I would seriously consider a small (few hundred Watts) AC inverter running from your solar battery bank... Would certainly "solve" your blinking LED house lights, rebooting a TV, etc. May be cost effective compared with a "true" UPS, better inverter hardware (pure sine wave, "hours" of AC output from your large solar battery bank, and you don't have the "extra equipment" (UPS+UPS battery replacement every 3-5 years and only "minutes" of backup power).

You can get an AC inverter with "standby" function (inverter "sleeps" until >8 Watt AC load is turned), remote AC on/off switch, etc... Example of small AC inverter with this functions:r

https://www.solar-electric.com/morningstar-suresine-si-150-12-120-60-b-inverter.html
https://www.morningstarcorp.com/wp-content/uploads/operation-manual-suresine-en.pdf

There are lots of ways of "addressing" the issue--Just need to understand your "sensitive AC loads sizing/wattages" and such.

Lots of small inverter options this days (used to be a few hundred Watt AC inverter was 12 volt and not many had sleep/remote switch options)... Now small inverters are also available in the 24 and 48 VDC battery bus units too.

-Bill

nyoffgrid

Thank you for the excellent info. 

I do not have a solar array. I am in a heavily wooded area and since I use my cabin for a night or two every other week or so - it made more sense to just have a 200ah battery 24v battery (LI) that will feed cabin and then at night I charge it with generator. I used a bluetti to power the cabin with geneset charging at night for the last year and it worked well but the battery was a little under sized so the 200ah 24v is about 2.5 the size. This weekend I finally connected the 200ah it went from 100% to 83% after 7 hours of use. I think that a full day at the cabin = 12 hours of use will bring me down to 70%. I will try that a few times and if it is true.. if it is true then I might be able to instead limit the charge to 80% so I then will fluctuate between 80% to 50% SOC which should extend the life of my battery considerably right ? 

I think the way to set such limit on the inverter charger: https://powmr.com/products/all-in-one-inverter-charger-3000w-110vac-24vdc

Is by setting the charging cut off charge voltage to where the battery chart shows 80%?  

I don't mind trying a UPS ( spending $200 or more on it even) if it is something simple where I can plug in between generator and cabin. I am hoping someone can recommend a good one? 

Last basic question: I know that charging the lifepo4 battery at below freezing temp is a nono. But discharging it at very low temp (like 10f? ) is fine? 

My winter plan is that when I arrive at the cabin, and let's say the battery is at 90% SOC but shows 25f temp - is to use the battery (will start the wood burning stove and use my AC heat pump to bring cabin up in temp) and after a few hours in the cabin - the battery should be in good temp so I can start charging at night using generator... that is my plan. 

RCinFLA

Inverter generators in rpm reducing ECO mode will clip their AC sinewave voltage peaks when a sudden additional load is applied.

Spinning up additional rpm's to support heavier loads is slow in terms of AC voltage slump timing.

LF inverters are usually more capable to fill in the peak current draw, compared to a HF inverter.  If current peak is too large the inverter may shutdown for overload surge current.  Again, generator engine rpm spin-up time is not fast enough to prevent this.

Dave Angelini

Hopefully the BMS will shut down the battery if you try to charge below 32F.
A quality battery/BMS does this BTW!  You need to be able to monitor battery temp in cold places!

BB.

Check with the Li Ion battery manufacturer regarding temperature ranges.... Typically charging is above freezing, and discharging can work OK below freezing. For example a random chart for LiFePO4 battery discharging:

https://appbattery.com/wp-content/uploads/2018/01/Discharge-curve-in-different-temperature.png

Up there in great white north--You should be able to find battery heating pads. Lead Acid batteries can self heat during use and your plan to discharge for a few hours may warm them up a bit... And people have said that cycling FLA batteries have kept them warm in an insulated battery box.

LiFePO4 batteries are much more efficient, and self heating probably will not be "good enough" to keep them warm. Heat from a warm room, battery heater+insulated box are probably a better match.

If you use an insulated box in a "cold space"... Make sure the "top of the box" is well insulated... If not, the heat will rise and cool the battery down quickly.

I would still like to suggest a separate small AC inverter for your "sensitive" loads.

A UPS typically uses a FLA (or other such as AGM/GEL/etc.) battery... And this will have the "cold soak" issues too. If battery is discharged and gets cold, then FLA batteries can crack the cases. AGM are supposed to be able to withstand cold+low SoC conditions better than FLA. In any case, you are adding "complexity" (charger/battery/inverter/etc.) to your system. Keeping things simple with your existing system, and adding separate small inverter/larger battery bank if needed/or even replace your inverter-charger with separate AC charger and AC inverter and make your own continuous conversion UPS.

FLA and other lead acid batteries do better in cold (can charge/discharge when sub freezing)--But lead acid still are less efficient and don't work as well at higher temperatures vs Lithium Ion. And Lead Acid have less cycle life vs Lithium Ion...

Smaller UPS will probably not run your larger devices (heat pump, etc.)... So need a larger unit, larger battery bank, etc...

-Bill

nyoffgrid

I am going there today. The battery has bluetooth app which works great so I will check the temp of the battery when I get there. We are still not in winter but will be interesting to see. We are already at 45f at night. Cabin isn't insulated very well. I anticipate going there in winter and it will be very cold so I will try to heat up cabin quick using my ductless ac heat pump (very efficient) and wood stove. Then hopefully in an hour or two it'll be in good temp. 

nyoffgrid

The last few times I charged my battery at night with generator (24v 200ah Li) I started at 70% soc and it took about 3 hours to get to 100%

What I hate is that when fridge compressor kicks in, and generator ramps up, it makes my inverter charger beep and stop charging.. It will resume after about 30m but that ain't good for battery I'm sure.

Had an idea.

What if I get a plug in timer (with battery back up) plug the fridge into it and set it to on all day except for those 3 hours when I charge battery.. That's when we go to sleep so no one will open fridge - should spoil food. That way it won't ramp up at night and disturb the charge? Thoughts? 

BB.

The fridge "cut out timer" is a good idea... Should not hurt anything.

30 minutes to "resync" with the AC mains after a quick "brownout" seems a bit excessive.

Some inverter-chargers have lots of parameters that can be configured--Such as minimum AC input voltage... Perhaps dropping that down to 90 VAC might work?

The long/smaller gauge extension cord may be a help too (as suggested earlier) to limit fridge starting surge current.

-Bill

nyoffgrid

Apologies. I meant 30s not 30m. Maybe even less than 30s. 

Glad you think that timer idea is good. I will order it and do it. I just need to remember to adjust the time on it when they move clocks. 

I did have something odd with inverter (it is not a top of the line so maybe it is what it is). When we just arrived I switched the inverter on (battery was at 85% SOC) and after about 30m or so my wife started the microwave. 1000w. The inverter is rated at 3000w. Everything worked but had beeping from inverter... no error code. It will do it evetime we used microwave. Next day it was fine. No beeping while we used microwave. I emailed the manufacturer.