Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

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raysun
Forum Emperor
Posts: 2240
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by raysun » Sat May 16, 2020 10:47 pm

I get this stuff can be and is frustrating. There's dozens of ways this stuff can go wrong and create a miserable reality. Electricity is just too central to modern existence. Being without it is akin to being thrown head first into the stone age. I emphasize with your situation, but in no way would want to be in it. I easily could have been, but am not because I took it upon myself to understand what needed to be done to do it right, and then did those things. But enough about me, lets talk about you.

TBH, there's a good deal to address to get everything on an even keel. That's the elephant in the room.

Do you know how to eat an elephant? One bite at a time. ;)

Nothing about your system will be worse than it is right now. So take a rational, step-wise approach and the situation will improve.

Here's a simple engineering truth (and this is an engineering project) - One can only manage what one can measure.

It is essential that objective measures be established in order that the system be recommissioned to meet your needs. The measures are fairly straight-forward, but most folks don't have the tools or the understanding to make them. With your Outback equipment, you may be able to make them in a relatively simple manner.

One question:
• Do you have an internet connection and a home network?

SandyP
Forum Guru
Posts: 397
Joined: Tue Jun 21, 2011 4:44 am
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2) July 2011
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by SandyP » Sun May 17, 2020 1:33 am

Hi Rob/Carla,
As has been mentioned, can you give us an indication of what your daily total power usage is?
If possible it would also be good to know what the split is between nighttime/daytime usage is as this will help with battery bank sizing and therefore also solar array sizing.
Thanks.

User avatar
EA6LE-ONE
Forum Guru
Posts: 106
Joined: Tue May 05, 2020 7:51 am
My RE system: System 1:
MATE3s, 3 x Radian GS8048A,
4 x FLEXmax 100, HUB10,
2 x EnergyCell 48V 2700RE,
1 x FLEXnet DC, 4 x FLEXware ICS Plus,
54 x PANASONIC VBHN325SA17 325W

System 2:
MATE3s, 2 x VFX3648,
2 x FLEXmax 100, HUB10
1 x EnergyCell 48V 2700RE,
1 x FLEXnet DC, 2 x FLEXware ICS
21 x PANASONIC VBHN325SA17 325W
Location: Providenciales, Turks & Caicos Isl.

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by EA6LE-ONE » Sun May 17, 2020 3:37 am

raysun wrote:
Sat May 16, 2020 7:21 pm
EA6LE-ONE wrote:
Sat May 16, 2020 7:13 pm
provo wrote:
Sat May 16, 2020 3:27 pm


No....the generator output is connected to the AC IN of the inverter through a circuit breaker. (The inverter is connected to the hub.) When AC power is applied to the AC IN of the inverter, the inverter becomes a charger for the batteries, and also passes AC through the inverter to the loads. In that state it stops being able to invert DC to AC.

You might want to read the inverter manual and the charge controller manual cover to cover before making any more changes to the system. There are some basic concepts you should have "under your belt" before continuing.
Provo,
The generator is DC. 0-30V. Should be turned on through one of the relay and the output should be connected directly to the battery.
Hmm... All the Northern Lights gensets I know about are AC. Do they make a line of DC gensets? OP doesn't mention a model on his profile, just output.
My fault here, i quickly looked for DynaGen GSC 300, which is the controller, and been thrown a bit by the question with changing the fm60 to 80 that will help with the generator and jumped to the conclusion that he is trying to use a DC generator with the chargers.

https://dynagen.com/sites/default/files ... GSC300.pdf

Next time i should take my time to read to the end and don't jump to the conclusion.

Rob/Carla
Forum Whiz
Posts: 37
Joined: Fri Sep 18, 2009 9:07 pm
My RE system: Off-Grid,
12 REC TWINPEAK 2 REC285TP2 Solar Panels - 285w,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS25PS Batteries,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS27PS Batteries,
Mate Control Console,
2 Flexmax 60 Charge Controllers,
2 VFX3524 Inverters,
9kw Northern Lights Lugger Diesel Backup AC Generator with DynaGen GSC 300 Auto Start Engine Controller

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by Rob/Carla » Sun May 17, 2020 6:51 am

My system is not yet hooked up to my computer network. I had hoped to purchase an FNDC battery monitor or equivalent quite a long time ago, but obviously have not got there yet. It's itemized in my 'wish list' for the next series of up-grades. The price was quite high for a long time, but last time I checked it was a little more in my budget, just a few hundred dollars, so I hope to include one in the order when I up-grade the chargers. In the meantime, that's not a possibility for at least a few weeks or months.

raysun wrote:
Sat May 16, 2020 10:47 pm

One question:
• Do you have an internet connection and a home network?

User avatar
EA6LE-ONE
Forum Guru
Posts: 106
Joined: Tue May 05, 2020 7:51 am
My RE system: System 1:
MATE3s, 3 x Radian GS8048A,
4 x FLEXmax 100, HUB10,
2 x EnergyCell 48V 2700RE,
1 x FLEXnet DC, 4 x FLEXware ICS Plus,
54 x PANASONIC VBHN325SA17 325W

System 2:
MATE3s, 2 x VFX3648,
2 x FLEXmax 100, HUB10
1 x EnergyCell 48V 2700RE,
1 x FLEXnet DC, 2 x FLEXware ICS
21 x PANASONIC VBHN325SA17 325W
Location: Providenciales, Turks & Caicos Isl.

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by EA6LE-ONE » Sun May 17, 2020 8:03 am

Rob/Carla wrote:
Sat May 16, 2020 9:03 pm
Thank you. I imagine that I may seem defensive, but I can most certainly do without the 'pig piling'/bullying. I'm sorry, but I don't know what 'OpticsRE' is.

The system was originally supposed to be more than large enough for our power usage, but was installed at roughly half the size that it should have been, so far as we can establish. We have been juggling power usage and charging routines for ten years and burning discouraging amounts of diesel on many sunny days while struggling to up-grade after having used what we had been led to believe from the vendor's calculations and estimates was an adequate bank loan for the build. This has been emotionally and mentally exhausting and financially crippling. We've had AC failures the last two winters in a row where the AC backup broke down in the coldest parts of the season while one of us was away for weeks at work. Our emergency AC welder/generator also broke down that first winter at almost the same time that the main unit died, and both winters we had to spend thousands of dollars that was ear-marked to go for up-grades to the system on an expensive rental unit instead, while the generator was being rebuilt for the second time. I'm no electrical engineer, obviously, but I had the impression at the time that I'd done sufficient research and thus was not prepared for this situation, or for the apathetic attitude and complete lack of technical support from our original vendor. We've managed to go through two generators, which Rob(I'm Carla), has now rebuilt into one unit, and we recently purchased a gasoline generator to replace the emergency welder unit in case of another AC failure. We've upgraded the solar panels once and upgraded from the first set of batteries, replaced and repaired at least two faulty inverters, dealt with various electrical failures, and then recently added another six batteries, thinking that this would solve the bulk of our problems. Next, from what I've gleaned from the posts so far, it seems that it might might be a good idea for us to budget for an up-grade to the charge controllers and perhaps add some more panels.
To build a complete off-grid system is expensive if is done right. The grid-tied systems will be much cheaper and if is possible you should go for it instead off-grid.

There are many factors to consider:

Fist of all is that if you have grid power and the cost of it. in my case the cost per kilowatt is 0.40$ and for the cost of my system I need the batteries to last 12 Years (unrealistic) to break even. Then I have to change the batteries and wait another 8 years to recover that investment assuming that i have no other failures(unrealistic again). Because I live on an island, the cost of equipment is 30-40% more than in US.

If you have access to cheaper power than 0.40$ and want solar is only because is your hobby or you do it to save the planet, but you will pay more. Here the local company has no interest to buy your extra power you could generate with solar. The only way to use their grid is that everything goes to them and they sell it back to you without fuel charge cost, about 0.26$. One way to do use solar cheaper is to have hybrid system with very small battery and take advantage only when is sunny and the rest is coming from grid. the most I can get this way is about 30% off my power bill. In this case will take about 10 years to recover the investment if no other failures. might take longer depending on the size of the battery that you have to change every 5-6 years.

If you don't have access to grid power or other source of power that will be less than 0.50$ per kilowatt then you will consider to go full off-grid. One other requirement will be to design and install all the equipment yourself. Having a 3rd party install and maintain your system will increase the cost a lot more and in most cases they are to grab your money and selling you "fairytale" systems.

Now, once you decided to go full off-grid this is in my opinion the requirements for a good system:

Try to source all the equipment from one manufacturer like Outback, Schneider, Xantrex etc, the solar panels, batteries, electrical components, wires should be also from brand names, don't go cheap and try to get Chinese crap.

The size of the PV array should be at least 2 times the daily power usage, depending where you live (solar potential in you location) and the panel orientation.

The battery size i consider at least 4-5 times daily needs, bigger is better as will have a longer life cycle (specially for big batteries that you cannot move easy around, mine are 350 pounds each and take 3 people to move it around).

Type of battery: i opted for AGM batteries with no need for maintenance, can be installed indoors and acceptable cost per KWH. Flooded are cheaper and can be maneuvered easily as you can deploy them without electrolyte but they require regular maintenance and need to be installed in a vented room with no other electronics or equipment. Lithium batteries, many new types that are coming out on market this days, more expensive and untested for long term. On paper they are looking good but with all the potential danger associated I think is risky to have them.

The batteries should all be the same model and age. 2V cells and the biggest you can get for your needs. Best is to have one string of batteries per system, 2 strings in parallel will be OK as long wiring is done right (need to be checked more frequently).

Wires should always be the correct size according to the amperage and length. Bigger gauge always better but more costly. Higher voltage for DC inverter will results in smaller gauge .

The inverters size should be the sized correctly. one way is to have a load tester that will determine the maximum load for every appliance that you will need to power and add all up and have the size you need, add 20% more just in case. In real life you will not use everything in the same time. but what if everything turns on in the same time?

Most inverters are 12VDC, 24VDC, 48VDC. Chose 48VDC for more than 2KW, the wiring is 4 times smaller than the 12V.

Charger controllers should be the highest amperage you can get with high voltage from PV. The best now from Outback is FM100. Higher voltage from PV, smaller wires too.

Very important for the health of the battery is the battery monitor.

Be sure you have all the necessary protection equipment in place.

I am not a professional, this is just I gather from reading through forums from other people experience and having experimenting with PV equipment in my own house. Last 6 years i had an 7.2KW outback system with 72kwh battery that helped me to design my new system in the new house i built with solar in mind.

In the last month and a half since i finished installing my last solar panel i had no need of grid power and my backup generator was not used at all. The outback equipment performed flawless. the only problem i had was with the MATEs not connecting to OPTICS but i found a way around it.

This forum is full with smart people that are ready to help.

I am happy to be part of this community :)

I hope to see more people with success stories of how they set their own off-grid or grid-tie systems and share their wisdom here.

I still have few more jobs to finish around the house and then i will try to get the pictures and share here.

If anyone has a better advice than what I wrote, please share. I will allays want to hear about better ways to optimize my design :)

Please excuse my grammar and language mistakes, not my first language :)

Rob/Carla
Forum Whiz
Posts: 37
Joined: Fri Sep 18, 2009 9:07 pm
My RE system: Off-Grid,
12 REC TWINPEAK 2 REC285TP2 Solar Panels - 285w,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS25PS Batteries,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS27PS Batteries,
Mate Control Console,
2 Flexmax 60 Charge Controllers,
2 VFX3524 Inverters,
9kw Northern Lights Lugger Diesel Backup AC Generator with DynaGen GSC 300 Auto Start Engine Controller

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by Rob/Carla » Sun May 17, 2020 8:44 am

Rob is a bit better with the electrical theory and he tells me that our usage averages out to about 25kwh per day, ie roughly 750kwh per month. If my understanding of the advice so far is correct, then we have about 3.5 kw of input available from our current system and our loads can go to about 4.800 kw or more when most of the appliances kick in. This almost always happens when I do laundry at the wrong time and the water system kicks in. If it's a cold winter day, for example, then the furnace might also kick in and the draw on the batteries, and in turn on the AC backup suddenly becomes quite high. Roughly 5kw is the number that I have used to estimate my usage as per the max loads of my water sys, furnace, etc. In other words, it appears that I need to up-grade to a system that will give me an input of minimum 5kw plus, or more ideally about 10 or 11kw, if using the equation of doubling the load plus about 20%. Rob thinks that a good first step might be to up-grade to flexmax 80 charge controllers and try to add some additional panels. I'm also looking into pricing on an FNDC unit or other appropriate battery monitor. Would this be a logical direction to go, budget allowing?


quote=SandyP post_id=72512 time=1589704417 user_id=6203]
Hi Rob/Carla,
As has been mentioned, can you give us an indication of what your daily total power usage is?
If possible it would also be good to know what the split is between nighttime/daytime usage is as this will help with battery bank sizing and therefore also solar array sizing.
Thanks.
[/quote]

Rob/Carla
Forum Whiz
Posts: 37
Joined: Fri Sep 18, 2009 9:07 pm
My RE system: Off-Grid,
12 REC TWINPEAK 2 REC285TP2 Solar Panels - 285w,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS25PS Batteries,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS27PS Batteries,
Mate Control Console,
2 Flexmax 60 Charge Controllers,
2 VFX3524 Inverters,
9kw Northern Lights Lugger Diesel Backup AC Generator with DynaGen GSC 300 Auto Start Engine Controller

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by Rob/Carla » Sun May 17, 2020 8:49 am

Thank you very much for the positive input and solid general advice. Suggestions that lay out some realistic steps forward are most helpful and appreciated.
EA6LE-ONE wrote:
Sun May 17, 2020 8:03 am


This forum is full with smart people that are ready to help.

I am happy to be part of this community :)

I hope to see more people with success stories of how they set their own off-grid or grid-tie systems and share their wisdom here.

I still have few more jobs to finish around the house and then i will try to get the pictures and share here.

If anyone has a better advice than what I wrote, please share. I will allays want to hear about better ways to optimize my design :)

Please excuse my grammar and language mistakes, not my first language :)

raysun
Forum Emperor
Posts: 2240
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by raysun » Sun May 17, 2020 9:08 am

Rob/Carla wrote:
Sun May 17, 2020 6:51 am
My system is not yet hooked up to my computer network. I had hoped to purchase an FNDC battery monitor or equivalent quite a long time ago, but obviously have not got there yet. It's itemized in my 'wish list' for the next series of up-grades. The price was quite high for a long time, but last time I checked it was a little more in my budget, just a few hundred dollars, so I hope to include one in the order when I up-grade the chargers. In the meantime, that's not a possibility for at least a few weeks or months.

raysun wrote:
Sat May 16, 2020 10:47 pm

One question:
• Do you have an internet connection and a home network?
Please forgive the fact this post is going to be a little bit technical. There's no way to provide you this information without getting into battery physics. I promise to keep it at the 101 level.

If something doesn't make sense, please ask.

The common analogy is a battery as a fuel tank. It's fairly apt. Instead of storing diesel, gasoline or propane, it stores electrical charge.

Like any fuel tank, a battery is filled up, and drained, of charge. How full a battery is at any moment is called the State of Charge (SoC).

Tracking battery State of Charge is perhaps the single most critical measure for operating an off-grid power system.

The type of battery used dictates somewhat how SoC can be measured. The type of battery in your system is called Flooded Lead Acid (FLA). Each of the 2 volt battery cells is in a separate compartment, and consists of lead plates submerged in an electrolyte of sulfuric acid and water. Each cell has a removable cap that allows the addition of (distilled) water in order to keep the lead plates fully covered.

There are three basic ways to measure SoC with a Flooded Lead Acid battery: measuring electrolyte specific gravity; measuring battery voltage; measuring charge flow into and out of the battery.

• Measuring electrolyte specific gravity
For a flooded lead acid battery, the most accurate way to determine SoC is to measure the concentration of acid in the electrolyte. The concentration varies directly with SoC, and is highest when the battery is fully charged.

Specific Gravity (SG) is measured using a hydrometer. Some electrolyte is withdrawn from a battery cell using the hydrometer, and a gauge on the unit shows the Specific Gravity.

The data sheet below is for your battery bank. The numbers show the relationship between SG and SoC
Screenshot_20200517-051622_Drive.jpg
• Measuring Battery Voltage
There is a relationship between battery cell voltage and SoC.
voltchart.gif
voltchart.gif (6.43 KiB) Viewed 912 times
For a 48V battery, multiply the measurement x 4.

Voltage is easy to measure, so is often used to estimate SoC. Unfortunately, voltage and SoC only correlate when the battery is completely at rest (no charging, no load) for at least 4 hours, and at a specific temperature. This is generally not practical for an off-grid system because the battery is always under load. Voltage measurements under load can be "off" relative to SoC by as much as 100%. In most cases, Voltage is an easy, but not reliable, measure.

• Measuring charge flow into and out of the battery.
Using the "fuel tank" analogy, measuring SoC by tracking charge flow into and out of the battery is conceptually simple. If we know how much charge a battery holds we can determine SoC by tracking the amount of charge put in and taken out. Capacity is measured in Amp Hours (AH). If the battery is 1000AH and starts out full, then 500AH is withdrawn, the battery is now at 50% SoC. If we then put 500AH of charge back in, the battery is at 100% SoC.

In practice the SoC calculations are more complex, but that's what charge tracking monitors like the FNDC are for.

All the above is a lot to chew on. Don't worry if it isn't all committed to memory. There are some important takeaways here.

• The battery should be fully charged at every charge cycle. For most off-grid systems the charge cycle is daily. Therefore, the battery should be brought back to 100% SoC every day.

• The battery should not be discharged below 50% SoC. Regularly discharging an FLA battery below 50% materially shortens it life. This underscores the importance of a good battery monitor.

• To understand the current usage of the battery, get a hydrometer and use it to measure specific gravity. Even a cheap "battery tester" hydrometer from an auto supply store is better than nothing. On that type the readings are "Good", "Fair", and "Poor". When fully charged the battery cells should test "Good", when at the most discharged (first thing in the morning) the battery cells should measure "Good" to "Fair". The cells should never measure "Poor". If the latter, then corrective action is in order.

• Relying on battery voltage to gauge battery SoC is not a good method. In practice, it can be done, but requires intimate knowledge of the specific battery's behavior, and of system loads.

• Adding an FNDC to the system is a priority. Without it, you are practically flying blind. Not knowing, and managing, SoC concisely makes a vast difference in battery health and service life. The FNDC is ideal for your system, but if its months away, budget wise, I'd suggest getting a cheap Chinese clone. They can be had for around $20. They won't replace the FNDC, but will be better than nothing, and will definitely get the SoC ballparked to a servicible degree.

The meter will also answer the very important question about daily energy use that's needed to address other aspects of the system.

Random search: https://www.amazon.com/Multifunction-Ba ... B07T9LV66P
(EDIT - I grabbed a 100A monitor at first, but then realized you have a dual inverter 24V system, so a 300A meter is necessary at minimum.)

Please slog through this info, and ask questions. This part is the toughest, and most important, piece of your system to understand.
Last edited by raysun on Sun May 17, 2020 3:50 pm, edited 3 times in total.

pss
Forum Guru
Posts: 499
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by pss » Sun May 17, 2020 9:27 am

I have re-read this thread. problems, problems,problems.

First off to answer and or solve:

1. What is your average load and maximum load and what time of the day will this occur, nighttime or daytime?
2. What is the average amount of sunlight at your geographic location in summer and winter?
3. What are your average summer daytime highs?
4. What are your average winter daytime low temperatures?
5. What is the maximum wind force at your location you have to plan for?
6. How far will the arrays be located (in feet) from where the guts will be housed (batteries, charge controllers, inverters)?
7. How many cloudy days in a row do you get from storms?
8. Do the typical storms reduce your PV output by 70% or 95% when they come through?
9. Do you have grid or generator backup?
10. How long do you want to power your typical loads with batteries?
11. How long do you want to be able to power your minimal loads with batteries?
12. Choose your batteries wisely and not blindly, knowing their physical characteristics for charging and discharging to match your system.

Once this information is gathered, a competent solar engineer can provide you with a drafted plan of the entire system from number of panels needed, all wiring diagrams and gauges, and necessary equipment to meet your needs. At that point, you will price out the equipment from all sources to determine if your goals fit your budget. If there is a match, proceed, if not make the necessary changes by scaling back. Finally, don't forget to price in labor and equipment rentals to construct the system (Mini-excavator, concrete mixer, saws, drills, etc). You may have to hire a structural engineer or other solar engineer experienced in solar mount designs to build a solid system. After construction come wiring the connections and this is where a good competent electrician comes into play. First, they can read the diagram and should not make mistakes in connections and secondly, they should have the experience to make certain lugs are properly torqued and splices don't come loose. If you do these things, you will produce a system that meets your needs, if not, good luck.

At a certain point, the complexity of a solar powered system expands to the point where the probability of failure, need for service and parts and replacement parts comes into play vs. scaling back a bit and purchasing a generator to deliver some of the needed power on a regular basis. This is where more careful research comes into play. If you decide to use a generator on a regular basis rather than just an emergency basis, then a liquid cooled generator is a must, diesel or LP or natural gas. You can purchase excellent 4 cylinder units with and without turbos that can run provide reliable service for years for a lot less than all the PV stuff. Finally, if you just want to keep charging batteries, then a company like Polar Power will sell you a DC generator to meet the charging needs of your battery bank and keep you going with less wear and tear than an AC generator.

LASTLY, no one has commented yet that increasing a charge controller from 60 amps to 80 amps is nice, except that if you expand the array, you need to make certain that the wiring from the DC disconnect switch up to the charge controller can handle the increased amperage. And you also have to make certain that the number and gauge of wires is safe for inside the installed conduit (will not overheat, melt insulation and short out system) and don't make the mistake of running with too large a gauge to fit on the charge controller terminals.

SandyP
Forum Guru
Posts: 397
Joined: Tue Jun 21, 2011 4:44 am
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2) July 2011
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by SandyP » Sun May 17, 2020 9:54 pm

Rob/Carla wrote:
Sun May 17, 2020 8:44 am
Rob is a bit better with the electrical theory and he tells me that our usage averages out to about 25kwh per day, ie roughly 750kwh per month. If my understanding of the advice so far is correct, then we have about 3.5 kw of input available from our current system and our loads can go to about 4.800 kw or more when most of the appliances kick in. This almost always happens when I do laundry at the wrong time and the water system kicks in. If it's a cold winter day, for example, then the furnace might also kick in and the draw on the batteries, and in turn on the AC backup suddenly becomes quite high. Roughly 5kw is the number that I have used to estimate my usage as per the max loads of my water sys, furnace, etc. In other words, it appears that I need to up-grade to a system that will give me an input of minimum 5kw plus, or more ideally about 10 or 11kw, if using the equation of doubling the load plus about 20%. Rob thinks that a good first step might be to up-grade to flexmax 80 charge controllers and try to add some additional panels. I'm also looking into pricing on an FNDC unit or other appropriate battery monitor. Would this be a logical direction to go, budget allowing?
Yes with your estimated daily usage you are likely to need a ~10kw solar array (assuming 4 to 5 hours of sun per day).

A simple back of the envelope way of sizing an off grid system was documented by a user on another site as :

1. Determine Battery bank storage requirements

Battery Ah requirement = Wh usage per day * 1/battery bank voltage * 1/0.85 inverter efficiency * number days storage * 1/max depth of discharge

2. Solar array based on battery bank required charge rate

Array wattage required = Battery bank Ah * charging volts * 1/0.77 panel+controller derating * 0.10 rate of charge (10%)

3. Solar array based on daily usage

Array wattage required = Wh usage per day * 1/0.52 off grid system efficiency * 1/ Hours of Sun

So, given you already have a 24V battery bank of ~2700ah (C20) and a daily usage of ~25kWh then :

1) You have about 1 days storage at a depth of discharge of 50%

2) To properly charge the battery bank you need a solar array of ~10kW

3) Based on usage you need a solar array of ~10kW (assuming 4.5 sun hours per day).

PS. The chart below may assist in determining your average sun hours if you are in the USA :
Map1.gif
USA ave daily solar hours.
PPS. I gather you may be in Canada given the reference to "other Province" in an old post?
Last edited by SandyP on Mon May 18, 2020 7:13 am, edited 1 time in total.

SandyP
Forum Guru
Posts: 397
Joined: Tue Jun 21, 2011 4:44 am
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2) July 2011
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset
Location: Victoria, Australia

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by SandyP » Mon May 18, 2020 6:52 am

Rob/Carla wrote:
Sun May 17, 2020 8:44 am
Rob is a bit better with the electrical theory and he tells me that our usage averages out to about 25kwh per day, ie roughly 750kwh per month.
I should add, is there anyway you can reduce your daily kwh use? This will be "cheaper" than adding a significant amount of equipment to your existing system.

Rob/Carla
Forum Whiz
Posts: 37
Joined: Fri Sep 18, 2009 9:07 pm
My RE system: Off-Grid,
12 REC TWINPEAK 2 REC285TP2 Solar Panels - 285w,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS25PS Batteries,
6 Surrette 4v Deep Cycle Solar Series 5000 Model 4KS27PS Batteries,
Mate Control Console,
2 Flexmax 60 Charge Controllers,
2 VFX3524 Inverters,
9kw Northern Lights Lugger Diesel Backup AC Generator with DynaGen GSC 300 Auto Start Engine Controller

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by Rob/Carla » Mon May 18, 2020 10:43 am

Thanks to all who have given advice and helped us to assess our next steps. We are looking into our options, such as adding another Flexmax 60 charge controller, additional panels, and FNDC monitor and up-grading to a Mate 3 controller.

raysun
Forum Emperor
Posts: 2240
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Question, Battery Charge Settings/Defaults, Generator Run-Time Too long

Post by raysun » Mon May 18, 2020 10:58 am

Rob/Carla wrote:
Mon May 18, 2020 10:43 am
Thanks to all who have given advice and helped us to assess our next steps. We are looking into our options, such as adding another Flexmax 60 charge controller, additional panels, and FNDC monitor and up-grading to a Mate 3 controller.
If I may throw a pinch of salt into the pot and stir it...

Consider the FM80 rather than the FM60 for the next charge controller addition. The extra 25% headroom will be used. When the cooling fan fails on an FM60 it is a complete unit teardown to get the replacement fan installed at the back of the chassis. On the FM80 it's a 15 minute job to get the fan replaced at the front of the chassis.

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