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Inverter question

Posted: Fri May 22, 2020 2:59 pm
by Shroomer
OK I bought this inverter https://www.amazon.com/gp/product/B07W5 ... UTF8&psc=1

This battery https://www.amazon.com/gp/product/B00S2 ... UTF8&psc=1

and my question is why does the inverter keep charging the battery up to 14.3 v then stops and lets it fall to around 13.3 v then starts charging again

about 45 min charging and 20 to 30 falling...

Is this normal ? is this going to hurt my battery ?

this is working as a UPS for 2 high power PC's and a laptop and satellite internet router and dish

Any help is appreciated, please only helpful comments about my question thank you

Re: Inverter question

Posted: Fri May 22, 2020 5:12 pm
by raysun
The Inverter doesn't seem to have a lot of documentation available so I'm going on some broad suppositions.

When the unit is plugged into AC the internal transfer switch feeds the AC IN to AC OUT, bypassing the Inverter, as one would expect.

In this mode, the Inverter circuit is effectively run "backwards" as the battery charger. The charger function doesn't appear to be particularly sophisticated, having two phases: constant current, commonly referred to as "Bulk" charging, and constant voltage, referred to as "Float" charging.

Bulk charging proceeds to a point of overcharge (14.3V) then stops. Float holds the battery at a voltage (13.3) that assures it maintains charge without being over stressed.

Theoretically, the unit should hold the battery at the Float voltage until the AC IN is removed and the unit starts inverting. It doesn't sound like this unit is behaving that way. That could be for several reasons:

• The inverter/charger circuitry is defective, and the unit isnt tracking the charging state properly.

• The inverter/charger circuitry is defective, and the unit isn't staying in bypass when AC IN is applied.

• The Inverter has programmable modes that select:
Grid Priority - inverter bypassed until the AC IN is removed, either by pulling the plug, or by a power outage. This would be considered "UPS mode" in your usage.
Battery Priority - unit inverts drawing on the battery until it is discharged to a certain point, then recharges it from the AC IN.
I'm guessing this may be the AC/DC Priority feature, set to DC Priority, but it isnt clear.

If it is as described above, the 20-30 minute run time followed by 45 minute bulk charge may be (guessing here):
15 Amp x .67 Hour x 80% efficiency = 8AH total charge. The 100AH battery is being discharged 8-10% before charging starts. A wild guess would be discharging the battery 50% would allow 5 x .67H = 3.5H runtime. This could be off by 30-40%, but there's ways to determine it experimentally.

Will this cycling hurt the battery? Yes, for two reasons:

• Every battery has a finite number of charge/discharge cycles, called cycle life. How many depends on the depth of discharge. The battery specs will have a table listing this. What's not known is how deeply the battery is being discharged before the charger kicks in, but every time it does, it counts as one cycle.

• The charger seems to be missing a critical step between the Bulk and Float stages, called Absorb. Bulk will fill the battery to about 85%, at which time, a "very smart" charger would switch to a constant voltage stage that holds the battery at a controlled overcharge, slowly reducing the charging current until the battery has accepted as much charge as it is designed to hold. Then, and only then, would the charger switch to Float.

In the case of this charger, the switch from Bulk to Float is likely banking on an extended Float period to trickle in a topping charge. It won't be as much as an Absorb charge however, and will leave the battery slightly undercharged. A chronically undercharged battery will have a significantly shorter service life.

As a UPS, I'd think this battery to have about a 24 month life. After which time capacity would reduce to about 75%.

Immediate takeaway here is to explore the AC/DC Priority function and set the unit to AC Priority. You should see the behavior change to holding the battery at float until the AC is removed, at which time the system should start inverting, discharging the battery.

Re: Inverter question

Posted: Fri May 22, 2020 9:30 pm
by Shroomer
raysun wrote:
Fri May 22, 2020 5:12 pm
The Inverter doesn't seem to have a lot of documentation available so I'm going on some broad suppositions.
Hope this helps https://images-na.ssl-images-amazon.com ... vn3RHL.pdf

Many thanks for the reply

Re: Inverter question

Posted: Fri May 22, 2020 9:41 pm
by raysun
It doesn't say a lot.

It does claim a 3-stage charger. That's better than I guessed.

It does not appear to have any programming switches, or configuration settings, so it doesn't appear to have the AC/DC priority function.

Unless there's more information, it will be difficult to tell how this unit is supposed to function, and if its functioning properly.

Re: Inverter question

Posted: Fri May 22, 2020 10:54 pm
by Shroomer
raysun wrote:
Fri May 22, 2020 9:41 pm
It doesn't say a lot.

It does claim a 3-stage charger. That's better than I guessed.

It does not appear to have any programming switches, or configuration settings, so it doesn't appear to have the AC/DC priority function.

Unless there's more information, it will be difficult to tell how this unit is supposed to function, and if its functioning properly.
Yes I agree and have since pulled the 180.00 battery off it and am messing around with a old car battery (with proper ventilation). I want to see if it is doing the same with this battery also.

I do agree it does not appear to be going into a float charge mode at all.

I have a feeling this is going to be returned to amazon... do you have any recommendations for a replacement

Re: Inverter question

Posted: Fri May 22, 2020 11:47 pm
by JRHill
Shroomer wrote:
Fri May 22, 2020 10:54 pm
I have a feeling this is going to be returned to amazon... do you have any recommendations for a replacement
Yup. Find an Outback dealer in your area or an on line source like Northern Arizona Wind & Sun. Otherwise buy an inverter generator and keep lots of fuel jugs around which will probably be more reliable than what you've tried so far. In the end it depends the stability and longevity you expect from your power system. And you'l need the generator sooner or later anyway.

Re: Inverter question

Posted: Sat May 23, 2020 5:39 am
by raysun
Shroomer wrote:
Fri May 22, 2020 10:54 pm
raysun wrote:
Fri May 22, 2020 9:41 pm
It doesn't say a lot.

It does claim a 3-stage charger. That's better than I guessed.

It does not appear to have any programming switches, or configuration settings, so it doesn't appear to have the AC/DC priority function.

Unless there's more information, it will be difficult to tell how this unit is supposed to function, and if its functioning properly.
Yes I agree and have since pulled the 180.00 battery off it and am messing around with a old car battery (with proper ventilation). I want to see if it is doing the same with this battery also.

I do agree it does not appear to be going into a float charge mode at all.

I have a feeling this is going to be returned to amazon... do you have any recommendations for a replacement
Yes, I live in an area that does not have reliable power, and live totally off grid. Many of my neighbors do too. Many of them are on very small budgets.

Reliability in a small system is a challenge, but not impossible. The biggest problem is separating the "wheat from the chaff" in the flood of cheap chinese gear out there.

The next biggest challenge is setting realistic system specs., and building a system around them.

Here's some things I've noticed and helped folks address:

• Not understanding power requirements and controlling a power budget. Peak power demand is measured in Watts. Power consumption is measured in Watt Hours. For your UPS function, peak power is the sum of all the equipment plugged in. Read the Watt rating on each piece of equipment and add them up. They will total less than 1000W is my guess. 1000W for 1 Hour = 1000WH. More likely the steady consumption of your essential equipment (and some small LED lights, phone charger, etc.) is going to be 300WH or so. How long your UPS will run depends on battery size 100AH @ 50% = 50AH x 12 = 600WH x 90% (inverter efficiency) = 540WH / 300WH = 1.8 Hours. That number changes, if course, depending on true consumption. An inexpensive device called a Kill-a-Watt ($15-20 on Amazon) can measure peak and consumption accurately. Invest in one.

• Buying an oversized, crappy inverter. Just gonna say it and pass no judgement. Lesson learned.

Everyone on this forum uses a high quality Inverter with good capabilities and relatively high cost. I run a household with a 3000W Inverter. A 2000W Inverter for the UPS is overkill and actually very inefficient. You get what you pay for, and there's no free lunch. On the size/cost/capability scale this Inverter hits a sweet spot for many: https://www.amazon.com/Renogy-1000Watt- ... B01MS9EI8Q. I've helped install a few of these in whole-house systems and they work. It will handle the UPS function just fine, and then some. Also, this is a decent "Pure Sine Wave ", instead of a "Modified Sine Wave" inverter. Your delicate computer electronics will thank you for making that choice in AC output.

• Battery monitoring. That nice battery you have can be killed quickly if abused. It happens all the time. Measuring battery voltage is not a good indicator of usage. Measuring current in and out of the battery is the way to go. Those of us with 100% reliance on $5000 - $50000 batteries use sophisticated monitoring costing hundreds of $. A UPS function and $200 battery can work well with a $20 chinese clone monitor. (Random search): https://www.amazon.com/bayite-6-5-100V- ... B013PKYILS

Kill-a-Watt, Renogy 1kW Inverter, clone battery monitor = $450. Good investment in a high quality, heavy duty UPS. With the addition of more battery capacity and proper wiring, it could literally run a whole house essential needs during a power outage.

Re: Inverter question

Posted: Sat May 23, 2020 8:08 am
by Shroomer
raysun wrote:
Fri May 22, 2020 9:41 pm
• Battery monitoring. That nice battery you have can be killed quickly if abused. It happens all the time. Measuring battery voltage is not a good indicator of usage. Measuring current in and out of the battery is the way to go. Those of us with 100% reliance on $5000 - $50000 batteries use sophisticated monitoring costing hundreds of $. A UPS function and $200 battery can work well with a $20 chinese clone monitor. (Random search): https://www.amazon.com/bayite-6-5-100V- ... B013PKYILS

Kill-a-Watt, Renogy 1kW Inverter, clone battery monitor = $450. Good investment in a high quality, heavy duty UPS. With the addition of more battery capacity and proper wiring, it could literally run a whole house essential needs during a power outage.
well I did do some things right I guess then because i have had some of these items longer than others

battery monitor
https://www.amazon.com/gp/product/B07T9 ... UTF8&psc=1

breaker... Should I also have a fuse?
https://www.amazon.com/gp/product/B07F7 ... UTF8&psc=1

watt meter
https://www.amazon.com/gp/product/B0716 ... UTF8&psc=1

I also have a nice grounded lightning rod and surge protector setup

Re: Inverter question

Posted: Sat May 23, 2020 10:37 am
by raysun
Shroomer wrote:
Sat May 23, 2020 8:08 am
raysun wrote:
Fri May 22, 2020 9:41 pm
• Battery monitoring. That nice battery you have can be killed quickly if abused. It happens all the time. Measuring battery voltage is not a good indicator of usage. Measuring current in and out of the battery is the way to go. Those of us with 100% reliance on $5000 - $50000 batteries use sophisticated monitoring costing hundreds of $. A UPS function and $200 battery can work well with a $20 chinese clone monitor. (Random search): https://www.amazon.com/bayite-6-5-100V- ... B013PKYILS

Kill-a-Watt, Renogy 1kW Inverter, clone battery monitor = $450. Good investment in a high quality, heavy duty UPS. With the addition of more battery capacity and proper wiring, it could literally run a whole house essential needs during a power outage.
well I did do some things right I guess then because i have had some of these items longer than others

battery monitor
https://www.amazon.com/gp/product/B07T9 ... UTF8&psc=1

breaker... Should I also have a fuse?
https://www.amazon.com/gp/product/B07F7 ... UTF8&psc=1

watt meter
https://www.amazon.com/gp/product/B0716 ... UTF8&psc=1

I also have a nice grounded lightning rod and surge protector setup
Cool, those will work.

The little DC circuit breakers are pretty light duty but will work in this application. Fuse not necessary.

Circuit breakers/fuses are designed to protect wiring, not equipment, so be sure the rating of the breaker and wiring match.

Re: Inverter question

Posted: Sat May 23, 2020 11:29 am
by Shroomer
Sorry for the fast post this morning, I work on the farm almost 1000 acres. So during the day i usually have little time for the Internet.

This project started with the goal of being self sufficient for power. I know what I bought is no where near enough but I like to learn as I go. I just wanted to start with a inverter that can handle my re fridge or window A/C unit if need be for a little time. The inverter I bought handled both of them Individually just fine. That would of only been used in emergencies. It would power my Pc's for long enough to finish a project and not have to shut down in seconds with a standard UPS. So I had planed on building onto it with more batteries and then upgrading to a larger inverter later. Eventually adding solar panels down the road.

So short story over,
raysun wrote:
Sat May 23, 2020 10:37 am
Circuit breakers/fuses are designed to protect wiring, not equipment, so be sure the rating of the breaker and wiring match.
it is a 200Amp breaker(the inverter recommended it) and I figuring 2000 watts on 120v AC would equal 16.5 Amps x 10 for DC so the battery would be under 165 Amps load at max right?

Also Is there a real benefit other than less amps drawn going to a 24 v or higher system ?

Also (down the road) is there a way to have solar run along side the power company to offset my bill but not have a battery bank. But later have a charging battery bank along side of that system for whenever the power goes out ?

Re: Inverter question

Posted: Sat May 23, 2020 11:42 am
by raysun
Yes, a 200A breaker would be required, just be sure the battery wiring is rated likewise.

24V (and 48V) batteries deliver given power at lower current, a big benefit, especially in battery efficiency. They also permit a given capacity charge controller to handle larger solar arrays.

Check into AC Coupled solar arrays and inverters to see systems that provide solar power without battery storage. They work when the grid supplies power to help reduce power drawn. They don't work.when the grid goes down.

Re: Inverter question

Posted: Sat May 23, 2020 12:04 pm
by Shroomer
raysun wrote:
Sat May 23, 2020 11:42 am
They work when the grid supplies power to help reduce power drawn. They don't work.when the grid goes down.
So can you run a battery bank along side of said system ?

Re: Inverter question

Posted: Sat May 23, 2020 12:07 pm
by raysun
Shroomer wrote:
Sat May 23, 2020 12:04 pm
raysun wrote:
Sat May 23, 2020 11:42 am
They work when the grid supplies power to help reduce power drawn. They don't work.when the grid goes down.
So can you run a battery bank along side of said system ?
Yes, there are hybrid AC Coupled systems. This steps into the realm of the most complex systems out there. You can read through lots of threads here on the subject.

Re: Inverter question

Posted: Sat May 23, 2020 2:01 pm
by sparksalot
Look towards Radian or else FXR's in a FLEXPower...48 volt and never look back.

Re: Inverter question

Posted: Sat May 23, 2020 3:12 pm
by raysun
sparksalot wrote:
Sat May 23, 2020 2:01 pm
Look towards Radian or else FXR's in a FLEXPower...48 volt and never look back.
Yes, when it's time to go big league, the OB gear @48V is the way to go. Big $ ticket to do it all right, but it will be right.

Re: Inverter question

Posted: Sun May 24, 2020 11:10 am
by JRHill
Shroomer wrote:
Fri May 22, 2020 2:59 pm
this is working as a UPS
I didn't catch this in your original post when I replied. I was thinking of my 1st experiences with DC to AC. At the time it was needed for a building project on undeveloped land. I had a 1500 watt inverter which at the time (1990's) was a popular trucker's unit sold in fuel stops. I still have it and it works OK. It was tied to the dual batteries in a diesel and worked fairly well for AC in the pop-up camper and power tools. The next project (this current one) I went with four 12v RV/Marine batteries in parallel for power at the lodge tent and the tools, etc. I recharged them from the RV plug on the pickup. As the house was being completed I researched a complete off grid system - I can't recall how I came across Outback stuff but that's what I went with and built a 48v system. As raysun mentioned, yeah, it was big $ but I did the install so that helped a lot instead of hiring it out.

You are fortunate to have utility power available. I wonder how cooperative your electricity provider will be with a hybrid system as it seems the buy back varies so much from various locations? I'm sure others on this forum will be as interested as I am on how you progress. And the stuff you are currently planning can always be moved to an out building or made into a mobile power unit for a power source in the fields.