Looking for a home UPS that is smart

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That 52v is done for prolonging the life of the battery which for a LFP pack is 90% SOC. Say when you charge that regalia lithium pack at 20Amps or 1c the moment the pack voltage reaches 54v, at that point the capacity may be around 80% charged, the charge controller then slowly starts to ramp down the amps in order to maintain the 54v. But if you want to increase the cycle life of lithium battery be it 4.2v or a 3.6v chemistry you never charge it to 100% repeatedly, so you stop it at 90 or even 80% SOC. In this SOC the rest voltage will drop to about 52v.

Seems i need to teach myself about LFP cells, specifically what the correlation is between SOC and cell voltage. Here is a link

Strange thing is the difference in SOC between 3,3V and 3,4V. You don't need to go to 3.6 for a full charge, its already ~95% at 3.4V. And at 3.3V its only at 25%. There is a significant amount of charging that occurs between 3.3 & 3.4V. The chinese manufacturer's curve all seem to start at 3.4V so i'm assuming that is the max cell voltage it will be charged to.

This all has a bearing on run time. Do i assume 90% of rated capacity at full charge or less. Given as the battery probably does not discharge completely to 0. Maybe some margin is left 5 -10% ?

After me spending some $300 or more on LFP batteries over the past decade I can tell you that never charge them to full 100% SOC, unless you are absolutely sure that you are going to discharge it very soon. my first two prismatic 4 cell packs puffed abd bulged to 5x size in 1 year and but my 5 cell LFP pack are also now bulged to 5x the original size in 3 year time despite me storing them at storage voltage, the quality of those packs cannot be compared to mainstream use battery manufactures now, but my 2 Lifepo4 cylindrical cells are still working. As are all my 18650 based Li-on batteries.

Bulging means manufacturing defect. Can also be due to overcharging. I got a spare for my phone a year back. Used it twice and then it sat on the table and i notice several months later, it has a slight bulge. No overcharging possible here i think it was a manufacturing defect. Disappointing!

I wonder how Luminous will address puffed up cells with the Regalia battery ? its conceivable this mode of failure will be the more likely cause of shorter battery life span than cycle life. It can happen with any lithium chemistry as well.

What symptoms would suggest puffed up cells ?

It won't be apparent as the enclosure will contain it to a certain extent. What indications will there be. Lower run times, drastically lower if a string fails.

 

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The thing about LFP battery is their almost straight curve, so relying on voltage to estimate the SOC isn't going to work,. Back in those RC car races nearly 10 years back, when people didn't know about LFP chemistry, I used to get unfair advantage because of that flat voltage curve, while other RC cars running a lipo battery(those days lipo packs had almost linear curve)used to bog down as the voltage dropped, mine used to run just as fast as it started out in the RC track. Never worried about pack temperature but the same flat curve also proved to be a drawback, in one instance the car ESC shut itself down in the middle of my street because all of a sudden the voltage dropped below the cliff, near its depleted state(also with a puffed battery).
I have since used a power meter thats showed the mah drawn. Even my Icharger 208b I always rely on mah capacity termination for lifepo4 and eneloop nimh batteries, since if it relies on voltage termination, the battery used to almost certainly get overcharged.

Notice the regalia as a Rs485 port, the battery pack is measuring the amps, when the capacity is reached, it gives the message to the charge controller to stop charging.

That guy is using a cylindrical cell, those type of cell manufactures have consistency, where as those no brand prismatic type ones have lot of variation from chinese makers.

When my battery started to puff the capacity was lost by half, it also couldn't give those high amp draw short bursts. So the regalia should have BMS if one of cells is way of out of line it would stop charging, I mean those rs485 and rs232 ports are there for a reason.

The fact that these chinese sell makers apart from a one or two who don't give warranty of more then a year ot two, means they are not confident like say Tesla which gives a much longer warranty.

 

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Was going through an earlier post of mine and i caught an error in run time estimation for a two battery 24V system.

The single battery runtime calculation is correct but not for two batteries

This is to do with runtime. I'm talking what is the maximum load you can use to remain in spec.

For a single C20 it is 120W or 100W (with inverter at 80%) for 20h
For a single C10 it is 240W or 200W (with inverter at 80%) for 10h

Figures like this you'd think a C10 would be twice as good if not more than a C20 but that's not how the numbers shake up.

If your load runs the battery down faster than 20h for a C20 or 10h for a C10 then you are operating out of spec. Ridiculous but true.


Lets take a 200Ah C20

If the load is 500W, that means it is delivering 500 /12 or 42A

This means it can only work for 200 / 42 = 4.8h but this is assuming a perfect battery. By that i mean if you pull more than the spec amount of 10A then the battery capacity to deliver decreases

A C20 according to the Stan tubular table is only 66% if run down in 5h so you won't get 4.8h as calculated earlier but less

4.8h becomes 3.1h

Now if you want to limit to 80% DOD, take away another 20% so we're down to 2.5h

In addition consider inverters efficiency and its 20% down again to 2h

Result is a single C20 with a 500W load can be expected to deliver 2h run time

With a 200Ah C10

A C10 according to your sakthi table is 83% if run down in 5h

4.8h is 4h

Now if you want to do 80% DOD, take away another 20% so we're down to 3.2h

Now consider inverters efficiency and its 20% down again to 2.5h

So in the end a C10 delivers a half hour longer than a C20

With two batteries and the same 500W load. A C20 delivers 4h and a C10 closer to 5h.

Do you see the mistake ? i added up the run times of two single batteries for a two battery system and it does not work that way. If one starts with a multi-battery system then you have to account for it. And there is a quirk here.

Two batteries in series double voltage but not capacity.
Two batteries in parallel double capacity but not voltage.

Lets take two x 200Ah C20 in series for 24V

If the load is 500W, that means it has to deliver 500 /24 or 20.8A

This means it can work for 200 / 20.8 = 9,6h but this is assuming a perfect battery. By that i mean if you pull more than the spec amount of 10A then the battery capacity to deliver decreases

A C20 according to the Stan tubular table is only 80% if run down in 10h so you won't get 9.6h as calculated above but less

So 9.6h becomes 7.8h

Now if you want to limit to 80% DOD, take away another 20% so we're down to 6.14h

In addition consider inverters efficiency and its 20% down again to 4.9h

Result is a two C20 with a 500W load can be expected to deliver around 5h run time

This is more than double a single C20 it is 2.5 times more

With a two x 200Ah C10 24V

Since two batteries can work for 9.6h this is actually very close to the 10h spec of a C10

9.6h remains 9.6h

Now if you want to do 80% DOD, take away another 20% so we're down to 7.68h

Now consider inverters efficiency and its 20% down again to 6.14h

Again we see a similar 2.5 times more with two C10's from that of a single C10

And a similar 25% more run time of C10 over C20 whether in a single or two string.

What about with 36V and 48V systems. How do the numbers stack up

With a three x 200Ah C20 36V
If the load is 500W, that means it has to deliver 500 /36 or 13.9A

This means it can work for 200 / 13.9 = 14,4h

We're still short of 20h and the stan tubular table has no data for 15h so i'll take it as 90%

14.4h is 12.95h

80% DOD brings it down to 10.4h and the inverter efficiency brings it 20% lower again at 8.3h

Now the ratio of a 36V system compared to a 12V system is 4.1 times more.

With a four x 200Ah C20 48V
If the load is 500W, that means it has to deliver 500 /36 or 10.42A

This means it can work for 200 / 10.42 = 19,2h

This is pretty close to the C20 spec so i'll leave it as is

80% DOD brings it down to 15.35h and the inverter efficiency brings it 20% lower again at 12.3h

Now the ratio of a 48V system compared to a 12V system is 6.1 times more.

I will assume C10's follow a similar ratio with 36V & 48V systems

 

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It's common knowledge that higher voltage gives you much better performance. Even power tools have gone from 12V to 18V and now to 54V because they can now power much more powerful tools without worrying about high current draw.

 

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Apart from the lower strain on battery, look at the internals of a UPS or inverter. A higher volts is always preferred.
DC to AC converters inside the UPS or even DC to DC solar charge controllers are more efficient with higher volts. The more current is pulled from a battery or any device the more beefed up, will the requirement for the conductor, bus bar, Mosfet etc
Look at the below Solar charge controller. Even if you have lots of solar power available the battery determines the output power.
http://www.flinenergy.com/flinmpptscc-specs.html
Lets take a example of a wire a typical 1100v capable wire of 1sq mm can handle 12 amps that's 12000 watts max at 1000v input, but at 230v the same wire can only handle max of 2700w, now in 12v the same wire can handle only 144w. There is a reason Tesla model S car uses 400v battery pack, yet the charger cables are so thick, the upcoming VW electric cars and Tesla cars will use about 800v for even faster charge.

Inside a UPS even for this one criteria More Amps= More Heat= More cooling required= More power consumption.

 

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It's common knowledge that higher voltage gives you much better performance. Even power tools have gone from 12V to 18V and now to 54V because they can now power much more powerful tools without worrying about high current draw.

It's the way the numbers add up that is amusing

1 + 1 = 2.5

1 + 1 + 1 = 4

1 + 1+ 1 + 1 = 6

Wanted to derive what this guy says from first principles

 

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An extreme discharge test. 2.5C discharge.

Comparing VRLA, Gel & LFP. Interesting thing is he refers to the Exide as a no name brand

My calculation worked out once i figured that $600 inverter has 90% efficiency.

Killing a lead acid in under 10 mins means a 90% de-rating. The battery is only worth 10% of its rated capacity.

To match 40Ah of LFP for runtime requires 120AH of lead acid. Going by the comments it also costs the same

Then there is the cycle life thing to consider

 

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FYI, that exide shown in that video is EXIDE USA which has nothing whats so ever to do with Exide India. The USA brand even tried going after Exide India in Indian courts for the name, but they lost.

As long as one discharges at manufacture rated C rated capacity such as eg 100 ah @ c10 or c20, you will get that run time. For low power continuous discharge lead acid makes sense for now in terms of cost. GEL and VRLA batteries can never match the cycle life of Flooded lead acid batteries.

Like my Exide 40AH batteries its 9 years old with about 40% capacity left. I am almost able to get same run time as in 2010 (when battery was new) by changing to more efficient LEDs and BLDC fans.

 

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For low power continuous discharge lead acid makes sense for now in terms of cost.

I was looking at this and at other numbers blr_p has mentioned in his posts and it seems that the lead-acid batteries seem to be a poor choice for a completely off-grid setup. They don't seem to be VFM at all.
What do people use in off-grid setups. Do they oversize their solar panels and use the generated energy directly with the surplus energy getting stored in batteries and being used at night. I remember reading about the dilemmas such a system causes with people having to oversize by nearly 2 times, both the panels and the battery banks. Seems that grid tie-in systems are the most effective both cost-wise and ease of use when it comes to consumption, apart from the issue that grid tie-in means you will lose your supply as well when electricity goes out.

 

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I was looking at this and at other numbers blr_p has mentioned in his posts and it seems that the lead-acid batteries seem to be a poor choice for a completely off-grid setup. They don't seem to be VFM at all.
What do people use in off-grid setups. Do they oversize their solar panels and use the generated energy directly with the surplus energy getting stored in batteries and being used at night. I remember reading about the dilemmas such a system causes with people having to oversize by nearly 2 times, both the panels and the battery banks. Seems that grid tie-in systems are the most effective both cost-wise and ease of use when it comes to consumption, apart from the issue that grid tie-in means you will lose your supply as well when electricity goes out.

For cycle life, Lead acid battery is no match to LFP or LTO packs. But we in India cannot compare the cost in those youtube videos, the people in the USA get lithium for less then half the price compared to people in India.
If you think it as a investment for 20 years, then you could go for a LTO pack which costs $700/kw for a good toshiba cells, those will easily last 25 years or more.The high end LFP packs are suitable for 10 to 15 years. While the low end 2000cycle packs sold in India are suitable for 5 years. Lead acid needs to be replaced every 3 to 5 years if discharging to 80 and 50% respectively. But we don't know how much lithium battery will fall in price once the Indian production starts. Further more there will be a ton of used lithium batteries from cars and two wheelers which will be discarded since they no longer will be suitable for vehicles after capacity drop meaning you can no longer get from the desired point A to B but are perfectly fine for stationary batteries like for solar application, assuming you have the space for batteries.

Yes Grid tie is cheaper but that is the only pro and rest are all cons.

As you said their will be no power to the house once the grid supply fails. Also being directly connected to the Grid voltage spikes can screw up the Grid tie inverter, higher failure rate vs off grid ones. The contract to supply power to utility is more then 20 years, also lots of red tape and bribes in getting Grid tie sanctioned. The bribes money can instead get you one or two batteries.

Off Grid is useful for those who wish to have uninterrupted power. For a large size inverter 1kva and upwards, you will at the minimum require 2 to 4 batteries. The only difference between a regular inverter and off grid solar inverter is the solar input with MPPT. Cost of the panels is the same for off grid or grid tied.

In my case I will mostly get solar power from roughly 9am till 4:30 pm, during this time pretty much everything will be powered via solar only. High draw devices like water heater and induction stove will be On during the peak sun light time. In the night only fans, lights, lcd tv and other small devices will run via battery.
Even with all BLDC fans running 4 at a time, the consumption in night is only 140watt/hr at max speed, another 100 watt for all the chargers/adapters etc, 50w to 80w for inverter self consumption. Led lights no more then 80watt combined. After 11pm, no lights only fans and fridge and power adapters will run, which is well within the lead acid battery C20 discharge rate.

Even my 1.5 ton AC only consumes a constant load of no more then 350w at night at 23C, after it as achieved the set temperature. And when AC is running the fans are Off.

 

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Actually my case is of a commercial venture. I have higher usage needs with machines ranging 5-8kVa. I have a 4200sq ft roof area which can be covered with solar panels. However, we also have one of the cheapest electricity tarrifs at just Rs 4.65/unit for commercial ventures. Hence it makes the decision to go for solar that much difficult. If tie-in is available then I will be able to recoup my investment that much faster as all of the energy produced will be offset against my usage while not having to maintain a big battery bank. I can still keep a small battery setup to use for lighter loads in case of emergency. And those batteries will also last longer as they won't be used daily. As you have pointed out, totally off-grid setups won't make sense until Li batteries become available at cheaper price point in India.
Adding to my dilemma is that I will also have a choice of Biogas as well. But both, solar and biogas require me to make an investment and biogas can be used directly for heating purposes as well, which I might need in the future if going for pasteurization.

 

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Commercial and only Rs4.65/unit, which state is this. With machines of 5 to 8kv, I assume those are three phase machines, you will need some three phase capable inverters, which cost quite a lot. Solar panels will fall by 5% custom duties every year, just hope the rupee doesn't fall. For your application I would probably wait for a few more years, considering the low electricity price. Apart from sukam and luminous and few others all big name players are just rebadging Chinese inverters as their own.

 

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I am in Himachal, one of the few states that sells it's surplus electricity to other states.
Yes, the machines are 3-phase, but one can use VFDs to convert single phase into 3 phase if price difference between a single phase and 3 phase inverter is high. I will definitely wait it out, but I do want to change to renewable sources as and when I can.

 

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Let's look at the economics of a solar inverter 3kVA 48V setup. Here is a glowing review

Inverter - 43k
4x batteries, 150AH @ 12k so 48k
he now has 10 x 300Wp panels, let's say they are 11k each so 1L10

Total : 2L01 lets make it 2L

Now he consumes 1 unit a day instead of 10 which means his monthly was ~300 units/month, let's say that's Rs.2000 per month

He says he saves 90% now. So the savings is Rs.1800

How long will he take to break even ? 9.3 years (!)

Meaning if he has no more expenses he will be saving money after this point.

But how long will those 4 amarons last ? 3 years, 4 years or 5 years. They will be getting cycled every day and by maybe more than 50%

They are C20's so let's say 4-5. Meaning he is going to be paying for another four

How much longer will that take to break even ? 2 years

So now he is waiting 11.3 years and he needs the third set soon

I don't see the point given the outlay or is there a different way of looking at this ?

Every time his savings catch up , the batteries need to be replaced.

Let's say instead of just paying for backup we use solar to reduce the cost of consumption.

Now how long do just the panels take to pay off ? around 5 years

If you had just an inverter you would have to replace batteries at this point anyway but now your electricity consumption can come down. But because you have to cycle your batteries every day they eat into the savings and you have to replace them sooner than if you were just using them for backup

Still, by how much can electricity consumption come down? depends how much you generate and how much is consumed, during the day.

See, this is the thing. In homes the major consumption happens in the evening. The sun isn't up then. It's up during the day when consumption will be low as nobody's home or let's say day time use is low for a home. But for a commercial joint that's when consumption is at its peak. So solar could make more sense in a commercial setup than a home.

 

[NotMyRealName]

Wow, so you've finally reached your calculations to what i was saying forever...

So solar could make more sense in a commercial setup than a home.

The best example i can think of is the CIAL. Although i'm not sure if they're running on grid or backup after dark. My guess would be grid. I haven't really researched their system in detail, but just know that it's one of every mallus biggest bragging points...[DOUBLEPOST=1548988991][/DOUBLEPOST]Ok, no batteries: https://en.wikipedia.org/wiki/CIAL_Solar_Power_Project#Overview[DOUBLEPOST=1548989052][/DOUBLEPOST]So 40 MW takes 45 acres. Hmm...

 

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. So solar could make more sense in a commercial setup than a home.

Or for a place where electric supply is bad. My Mamaji's village in Haryana barely gets 4-6hrs of electricity a day. He is already using multiple batteries with conventional inverters as well as having to keep a generator handy.

The batteries are definitely the Achilees heel of a solar setup for domestic purposes, but things will be very different in 5 yrs when Lithium batteries start becoming much more affordable.

 

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Or for a place where electric supply is bad. My Mamaji's village in Haryana barely gets 4-6hrs of electricity a day. He is already using multiple batteries with conventional inverters as well as having to keep a generator handy.

Right, in that case it isn't about saving money its just about having electricity.

But in places where there is adequate electricity and just brownouts how much sense does it make. People are operating on the assumption that energy costs will keep rising and that could shorten the break even point.

The govt has been bullish on solar. So what incentives have they offered so far ? 30% subsidy in Karnataka. Even here they mention the pay period is 10 -12 years. When i looked into this it was quite restrictive as to what you can buy and from whom. They have their designated vendors.

There are also income tax benefits. Commercial setups have accelerated depreciation they can work into the costs.

How would that affect the final cost ?

The batteries are definitely the Achilees heel of a solar setup for domestic purposes, but things will be very different in 5 yrs when Lithium batteries start becoming much more affordable.

Exide has a JV with some swiss company called leclanche to make lithium batteries in India. Maybe in a couple of years Exide will offer Lithium battereis.

 

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The way I see it for my case, my 9 +year old batteries needed replacing and they needed to be upsized and now that I need to add another set of batteries to replace them and also add a inverter for another floor. I just decided to buy a single high powered Inverter that is also solar capable, So now by using 4 batteries in series vs a 2 battery inverter/ups per floor, I am able to maximize the battery and inverter efficiency this way, less amp draw on the batteries.

So from point of view, I only paid extra for the solar ready part of the inverter, which is about 20k extra. I will be adding 5kw of solar panels,( which is a good several months away). Unlike everyone else, every bit of the installation and overall design of the solar setup is done by me and with help from my dad, so the cost is much lower then the quotes you get by firms. I will only require a welder for the frame, (I already have a Esab DC welding machine but no skill ) or could even use bolt and nuts, with a more expensive aluminium frame.

Even still if I wanted, I could go for even 100ah x 4 batteries. So that ROI is got back sooner, (or even go for 50ah x 4, if I only need back up for fans and lights, in the night, now possible due to bldc fans). During sunlight time the when power goes, the battery will not be used.

In the night the only things that run for anything longer then 1 hr are bldc fans, led lights, lcd tv, fridge.

In sunlight time directly off solar water heating, cooking for after noon, water pump, washing machine. My bi weekely routine cleaning house vehicles from 3.1hp pressure washer and filling air to all the vehicles tires and cleaning air/cabin filter once in 3 weeks via a 3hp air compressor and in summer one or two 5 star inverter outdoor units are also cleaned via compressed air for maximum efficiency. This all will be done via solar power.

Also when the people who are back from work already they will have water heated for the next day, by using a larger 150l to 200l solar tank heated by solar electricity. The room would have been pre cooled to match the outside ambient temperature. In summer in bangalore by 8pm the ambient temperature would have dropped to 26c by 11pm its 24c.
A non air conditioned room with no directly exposed roof to sun, the ceiling temperature is about 33 to 36c at 11pm in the night, this temperature would be neutalized when the AC is running vis solar, with the walls and floor remaining much colder, now at night via battery or even grid the 1.5 ton AC will only run at 12 to 20% load, through out the night which is 200w to 350w/hr.

Also once, I add a electric scooter with removable battery pack. I will be milking my solar inverter to the max, it will never be idle.

 

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Wow, so you've finally reached your calculations to what i was saying forever...

What is complicating my decision is whether today do i consider an inverter that can use solar in the future or not ?

If nothing interesting appears in this space for the next five years then maybe solar capability isn't necessary right now.

The choice is whether to gradually build a system you can add to over the years or just restart from scratch each time batteries or inverter dies.

 

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I saw in one youtube video where they said, a well informed person can sell old batteries to dealers for as much as 95/kg. Not sure those are battery dealers or lead scrap dealers.

Here in bangalore at best the battery dealers gives about 10% off a new battery in exchange of old battery. A battery like exide 200ah c10, the dry weight is 54kg dry,even if you subtract 7kg off it, thats like 4k to 4.5k per battery, but the battery dealer will only give you like 1.9k to 2k max, lead ingots on the other hand 10kg costs Rs 1500. So those scrap dealers would melt them into ingots and make more then 6k off a 200ah battery.

So thats another advantage the lead acid batteries have over lithium. Lithium battery recyling is currently uneconomical.