Would you buy if offered Battery Bank?

[SunEagle]

Well, the way he posts makes me think he is some wet-behind-the-ear 20 year old graduate or a stuck up engineer who needs to retire his degree.

If he does have the knowledge and experience as you say then he is being senile and picking fights for amusement; then he got the best of me.

If I provided the plans to any engineer I guarantee they would stamp it. I guarantee both of you would sign off on it as well. You both would also agree that the batteries I use would go at least 15 years if not 20 once you look into the design and chemistry make up.

You would also agree: climate-controlled storage box with a "Void Warranty if Broken" would help prolong battery banks and equipment. You would also agree that discharging each battery in the bank at less than 1amp each would also prolong them and discharging them by only 20% of capacity would do the same. Though the batteries I am using can be drained down to 20% capacity and have no effect on performance and in all reality doing this actually prolongs the batteries.

Interesting that you and that battery manufacturer have come across something that very large companies and research departments have missed or forgotten.

What ever the history of your "battery" I wish you luck getting it to market. I do look forward for an energy storage system that most joe blows can afford and justify.

[einsvanian]

Thank you, my goal is to make large banks affordable for instance: just read that Tesla and Sonnen banks are only 7kwh and 4kwh. The ones I have been talking about are 72kwh and 144kwh at $10k starting price. If you all want a 4kwh bank for $2k we can provide it but we will not offer a 15 year warranty maybe a 3 year at most; I might be able to push 5 years using smaller banks but cycling will definitely be involved into the calculations.

Keep in mind: turning on your clothes dryer will cycle Telsa's and Sonnen's bank once in one hour and then some.

[SunEagle]

Based on a quick calculation a 4kWh battery with a daily cycle of 100% for 3 years would generate ~ 4300kWh. At $2k that comes to ~ $0.46/kWh. More than likely you would only get about 80% DOD per cycle so that comes to ~ 3500kWh or ~$0.57/kWh.

Since I only pay about $0.11/kWh it would be very hard to financially justify an energy storage system.

Maybe in a few years when the price of that energy system comes down to $0.15/kWh over its lifetime people might jump to purchase one. But that is much lower then what you are quoting now and I would guess the price will stay high if you get to a 15 year lifespan..

[Sunking]

Sunking, I am sorry you feel that way. News flash your MSEE, PE are pieces of paper as well..

You forgot to add a STAMP as well and is recognized by Authority Having Jurisdiction.

Your so called Certification is completely WORTHLESS not even recognized by your Mother.

[einsvanian]

My mother is dead and 6 ft under, no need to bring her into this. She died when I was 19. I am not going to play your games.

[Sunking]

I already know how MPPT works; I use it on the 6400ah battery banks at work. It is just one way to charge batteries. I use a much smarter way.

No you don't, you already proved that and makes it very easy to see you are a FRAUD.

BUSTED

MODS you need to ban this guy, he has proved he is a Liar and a Fraud. Not to mention a SPAMMER. What are you waiting for?

Only one who believes him is DAN

[DanKegel]

I am sceptical of the OP's project, but I wish it luck.

But claiming there is no such thing as a California certified electrician seems wrong; the state publishes a list of them. I can't understand why you disregard that fact. Admitting you're wrong on one tiny fact wouldn't hurt your argument; it would enhance your credibility.

[einsvanian]

Based on a quick calculation a 4kWh battery with a daily cycle of 100% for 3 years would generate ~ 4300kWh. At $2k that comes to ~ $0.46/kWh. More than likely you would only get about 80% DOD per cycle so that comes to ~ 3500kWh or ~$0.57/kWh.

Since I only pay about $0.11/kWh it would be very hard to financially justify an energy storage system.

Maybe in a few years when the price of that energy system comes down to $0.15/kWh over its lifetime people might jump to purchase one. But that is much lower then what you are quoting now and I would guess the price will stay high if you get to a 15 year lifespan..

$2k was just an estimate actual costs are around the $900 just like Sonnen which is $0.20/kwh. I can probably get the cost down to maybe $700 with a 3 year warranty @ $0.16/kWh.

[einsvanian]

I just did the math: with the 72kWh for 15 years @ $10k comes to $0.03/kWh: if you go just for 5 years it is: $0.08/kWh.

[SunEagle]

Yeah. But why would I purchase a 72kWh system when I average about 45kWh a day. Seems like leaving a lot of money on the table to me.

Even if the battery price comes down a solar pv system is not in the cards for me until I build my retirement home in a couple of years.

[einsvanian]

The larger the battery bank the less damage you will do to the plates in each battery.

Using the 72kwh battery bank:
(If I could get your total night time use I can get better calculations.)
Throughout the day your consumption varies hour to hour; lets just use the average of 1.9kwh (45kwh/24hours)
You consume 1.9kwh per night which totals to 34.2kwh.
You just drained your battery bank by 47.5% of its capacity
Leaving about 52.5% capacity left in the bank.
I would recommend the 114kwh battery bank.

Using the same numbers as above with the 114kwh bank:
34.2kwh drains the bank by 30% leaving 70% capacity left in the bank: less damage to the plates.
I would even recommend larger: a 171kwh bank will drain down by 20% leaving 80% capacity left in the batteries. With this I can provide a 15 year warranty.

Rule of thumb: they say do not drain your batteries below 80% of capacity.

Anything smaller than 72kwh bank would drain down by over 50%. This will definitely damage your batteries.

Lets use the 16kwh system from Sonnen:
You wouldn't even get through the whole night before your batteries shut off. You would get about 2 hours of run time. This is a battery back up system.

My 600ah bank provided 10.8kwh which gave me 6 hours of run time at 1.8kwh. On a 24vdc bank I was discharging by 75amps per hour which drained my bank down to 20% capacity which I had set the LVD (Low Voltage Disconnect for those who don't know).

With that said you can get by with a 45kwh bank but would need replacing within 5 years.

[foo1bar]

I just did the math: with the 72kWh for 15 years @ $10k comes to $0.03/kWh: if you go just for 5 years it is: $0.08/kWh.

$.03/kwh?
Wow.
Who would actually pay that much? I know I wouldn't. And $.08/kwh? Holy <*****>.

I suppose it's cheap if you're off-grid and you're normally paying over $.50/kwh for batteries and it can do the same job and do it at that price. (I'm skeptical that it can - because if it could why isn't it already being done?)
But for those of us with grid tie, that's a really expensive proposition.

[einsvanian]

People are paying $7k for Tesla and $5.9k for Sonnen and their systems are under 10kwh. Their base unit is under 7kwh; their expansion packs run about $1k up to $3k.

You would have to buy 10 of their expansion packs to reach 72kWh I know for a fact you will be paying more than $10k to Tesla or Sonnen.

[SunEagle]

People are paying $7k for Tesla and $5.9k for Sonnen and their systems are under 10kwh. Their base unit is under 7kwh; their expansion packs run about $1k up to $3k.

You would have to buy 10 of their expansion packs to reach 72kWh I know for a fact you will be paying more than $10k to Tesla or Sonnen.

If and when your system hits the market you might see a nice income. But be careful that someone doesn't come along and hit you up with stealing someone's else's design.

[einsvanian]

If and when your system hits the market you might see a nice income. But be careful that someone doesn't come along and hit you up with stealing someone's else's design.

I'm using different equipment and batteries to include a slight difference in design.

[jflorey2]

I already know how MPPT works; I use it on the 6400ah battery banks at work. It is just one way to charge batteries. I use a much smarter way.

Given that you think it creates less heat in a battery, it sounds like you do not. An MPPT controller, by increasing charge current from a typical solar array, increases heat in a battery during bulk charging.

If you have any mismatched impedance what happens is that the voltage hits either a higher or lower resistance in the battery; when this occurs if high it has some of the charge reflected back to the charge controller and heat is created (bad for chargers); if low the batteries get high current which creates heat inside the battery (bad for batteries). Matching the resistance inside the battery the charge controller can provide a more smoother current with no reflection to itself

You are confusing AC impedance and DC impedance. With AC impedance you can get reflections from signals propagating down a line. With DC impedance, you do not. Solar power systems and batteries are designed with DC impedance in mind. (There are some interesting applications of AC impedance with respect to batteries - like determining capacity or cell degradation based on the complex impedance of the battery at specific frequencies - but these have nothing to do with heating during charging.)

AC impedance is a complex beast (pun intended.) DC impedance is a lot simpler, and is basically resistance. (NOT internal resistance, but resistance as defined by R=V/I - see details below.)

and doesn't over flood the batteries with high current.

MPPT controllers RESULT IN MORE HEAT IN THE BATTERY. (I'll use all caps; you seemed to miss this point last time.) This is because, for a given solar array, an MPPT controller will deliver more current than a PWM controller during bulk charge. (During absorb and float, of course, the battery rather than the charging system limits current.)

No matter what there will always be heat. MPPT minimizes heat and distortion between solar array, controller, and battery (bank).

MPPT MAXIMIZES heat in the battery and controller.

Batteries are not all the same: some will be higher in resistance and others will be lower. Manufacturers try to get them identical but that is only in a perfect world. MPPT takes the whole impedance and matches that. You will get different currents still going to each battery and that is where you get the miss matched resistance and heat is generated.

You're still confused here. The effective impedance of a battery during charging has nothing to do with the internal resistance.

Let's take an example:

Let's say you have a battery bank that needs 48 volts during bulk charging. If you charge at 1 amp, its effective impedance is 48 ohms (R=V/I.) If you charge at 2 amps, its effective impedance is 24 ohms. Great.

Now let's say you have a 48 volt array. A typical 72x4 cell string (the standard for 48 volt charging) will give you about 72 volts; this is standard for 48 volt charging, and allows headroom for absorb voltages even with reduced power due to high temperatures. Let's take some real world numbers using a real panel - a Solarworld 320 watt 72 cell panel. Let's assume a 1280 watt array to charge this battery, arranged in 2S2P. Peak power voltage is 73.4 volts; peak current is 17.56 amps, assuming STC. (That would be equivalent to a cold day in a place like Colorado, where you can actually get STC on a good day.) That's 1289 watts at an output impedance of 4.18 ohms. (Again, R=V/I.)

This does not mean that's the only voltage or current that the panel will put out. If you only draw 10 amps, for example, then you'll see about 75 volts. (This happens at an impedance of 7.5 ohms.) The panel will work fine like that, but the output will only be 750 watts. It is still working fine, but working into a non-ideal output impedance, so it's not generating as much as it might generate with a better impedance.. Likewise, if you connect it to a battery that keeps the output at 48 volts, the current will rise a bit (to say 18 amps) but power output will drop to 864 watts.

A PWM controller can only connect and disconnect the array. Thus the array is either connected or not, and when it is connected you see 48 volts at 18 amps. Total output is 864 watts.

Now let's talk about battery heating. Let's say your battery has a total internal resistance of .05 ohms. Heat will be (18^2*.05)=16.2 watts. This is the amount of heat generated with a PWM controller.

So with PWM controller: 18 amps into the battery, 16.2 watts of battery heating.

The MPPT controller will adjust its INPUT impedance to optimize power extraction. So it will adjust its input impedance to 4.18 ohms by using a buck converter and changing the operating pulse width. The conversion efficiency is around 96%, so the output power will be 1237 watts. That means 25.7 amps into a 48 volt battery. Heat is (25.7^2*.05)=33 watts - over TWICE the heating. (And a lot more POWER - which is why people use them.)

So no, you don't understand how MPPT works, and it does not minimize heating in the battery.

Either it transforms using maybe an isolation transformer or it uses solid state devices to reduce voltage; haven't really Google'd any schematics but it lowers the DC voltage with minimal loss to maximize power output.

90% of the MPPT charge controller products out there use nonisolated buck converters. (That is a switchmode power supply topology; it is neither an "isolation transformer" nor just a solid state device, although a buck converter USES solid state devices as switches.)

There is still loss but a lot less than PWM chargers.

No, a PWM controller has a lot less loss than an MPPT controller. An on-off switch is much simpler, and more efficient FROM THE PERSPECTIVE OF POWER LOSS IN THE CHARGE CONTROLLER. With our 1289 watt example, an MPPT controller will dissipate 52 watts; a PWM controller will dissipate under 10. (That's why MPPT controllers generally have fans, and PWM controllers do not.) The solar panels will not see more "loss" either - when you operate a solar panel at half its rated output voltage, it will happily supply it. It will NOT dissipate the remaining half of its power as heat; it just won't generate it to begin with.

So to summarize, a lot of what you believe is backwards - and there are some gaps in your understanding of basic electronics.

Now let's see if you can learn from this, or if your ego will prevent that.

[einsvanian]

Theoretical versus real world applications:

Real World:
Explain this then: at my job when I take battery temps with the nifty new laser thermometer that your tax dollars paid for why does the battery bank powered by MPPT registers lower temps than the battery bank powered by PWM?

This is why:
When the voltage is traveling down the wire and comes to resistance a portion of it is reflected back, aka CEMF (counter electromotive force). Pulsating DC impedance will create reflection and heat. When the CEMF is traveling down the wire dissipating as heat and then voltage is applied there will be reflection and resistance and heat created as the CEMF and applied voltage collides.

For instance: Crystals: when you shoot a DC voltage across a crystal that has so much flat surface resistance that it causes reflection and amplification as it bounces of its other flat surfaces creating a frequency. So you can't tell me DC does not reflect when it hits resistance. (Crystals are used in RC cars and many other applications: for instance: Oscillators or should I say inverters)

PWM created so much reflection in its on-off state (pulsating DC) that it created so much loss through heat at the charge controller. The reflection inside the PWM acted as resistance by dissipating into heat to drop voltage from solar panels so it can closely match the battery's voltage. Lower voltage and lower current against higher resistance creates tremendous amounts of dissipated heat. This caused each battery in the bank to receive unregulated amperage causing more heat. Batteries received limited power due to heat loss.

PWM's required solar panels to match closely to the battery bank voltage because of this.

MPPT minimized on the reflection and provided a more constant DC flow (better trickle charge). This is why you can add higher voltage to the charge controller and have a lower voltage on battery bank. It allowed installers to series more panels together creating higher voltage which lowers amperage (aka heat). MPPT acts as a high voltage load for the panels and acts as a low voltage source for the batteries. Allowing more regulated current for batteries to absorb and limits heat. There is minimal heat dissipated, therefore, less power is loss. Batteries received more power from the solar panels at lower resistance via the MPPT charge controller.

MPPT acts as an isolation transformer or an autotransformer. They all fell from the same tree of impedance matching.

Effective impedance is all theoretical. Real world impedance is the resistance inside the battery itself. As the plates degrade after several cycles the internal impedance decreases and allows more current to flow to the battery creating more heat. This is closer at the end of the battery life.

You will never change my opinion on how an MPPT works nor how a PWM works. I've seen both in action and I prefer the MPPT any day.

And by the way: MPPT MINIMIZES HEAT!

Another example of Theory vs Real World:
Theoretically my solar panel produces 320 watts when in real life it produces variable output or about 300 watts give or take.
To me my panels are 300 watts each.

[jflorey2]

Explain this then: at my job when I take battery temps with the nifty new laser thermometer that your tax dollars paid for why does the battery bank powered by MPPT registers lower temps than the battery bank powered by PWM?

From what you have posted so far, it is because you don't know what you are doing, and have set up your system incorrectly. But I'd have to examine the system to tell you for sure why you are seeing less charge current with an MPPT.

When the voltage is traveling down the wire and comes to resistance a portion of it is reflected back, aka CEMF (counter electromotive force). Pulsating DC impedance will create reflection and heat. When the CEMF is traveling down the wire dissipating as heat and then voltage is applied there will be reflection and resistance and heat created as the CEMF and applied voltage collides.

You don't know what you are talking about. You've googled the topic and learned about counter-EMF and are trying to apply it to this case. It doesn't apply. It applies to motors, not solar power systems.

For instance: Crystals: when you shoot a DC voltage across a crystal that has so much flat surface resistance that it causes reflection and amplification as it bounces of its other flat surfaces creating a frequency. So you can't tell me DC does not reflect when it hits resistance. (Crystals are used in RC cars and many other applications: for instance: Oscillators or should I say inverters)

No, you shouldn't, because they are completely different devices. A crystal as used in electronics is a device that resonates best at a specific (AC) frequency in an appropriate drive circuit; an inverter is a device that inverts a signal.

MPPT minimized on the reflection and provided a more constant DC flow (better trickle charge). This is why you can add higher voltage to the charge controller and have a lower voltage on battery bank. It allowed installers to series more panels together creating higher voltage which lowers amperage (aka heat). MPPT acts as a high voltage load for the panels and acts as a low voltage source for the batteries. Allowing more regulated current for batteries to absorb and limits heat. There is minimal heat dissipated, therefore, less power is loss. Batteries received more power from the solar panels at lower resistance via the MPPT charge controller.

They receive more current. That results in more heating. The math doesn't lie.

MPPT acts as an isolation transformer or an autotransformer.

No, it doesn't.

It does not perform the isolation function of an isolation transformer - and if you assume it does, you may end up killing someone or burning their house down. It does not provide the AC boost/buck that you get from an autotransformer. It provides the functionality of a DC-DC buck converter, with sufficient intelligence that the input impedance is maintained at the ideal VI operating point for the panel.

And by the way: MPPT MINIMIZES HEAT!

Learn the math; do the math. The math doesn't lie. Neither does reality.

Look, you clearly know something about solar power. But you are pretending to know far more than you really do, and are coming off looking like an idiot. And if your goal here is to convince people you are competent to sell them a battery system, that is counterproductive.

[einsvanian]

I didn't design the systems at my job, an engineer did. My job hired contractors to install it. I assisted installing but my job was to watch and make sure they did it to code.

I maintain the system and do daily, weekly, monthly, and annual reports on performance. Temps, voltage, amperage, wattages, and so forth. I check for operations and look for signs of intrusions or defects. I know the systems inside and out. Walked through the entire systems with the engineer.

[DanKegel]

einsvanian, the more you explain, the less convincing it is, I'm afraid. Stick to a simple story and you'll come across better.

[einsvanian]

Thanks, Dan.

Yea, I realized I made several mistakes on this thread:

1st off: I started the thread all wrong should have kept it simple for instance: Is there a demand for battery banks? Would have been a lot better.

2nd: should have never gone into details where others could nit pick everything and take things out of context.

3rd: continued to explain my views and opinions.

But hey lucky I'm not the sales representative.

I would consider this thread no longer functional. It never ended where it was intended to go.

[einsvanian]

To Everyone on here,

Thank you, for your responses and sharing your knowledge, experiences, and opinions.

I really do appreciate it.

I've taken few things from all this:
It is not feasible to provide battery banks to a market that is not there.

I'm not a sales person.

Do not go into full details.

And...

That MPPT's minimize heat to the batteries!

[Mike90250]

Nobody but a complete fool, is going to buy a "magic box" that claims to contain 72KWh in it and a 15 or 20 year warranty. Because the battery does not exist that can do that. Lithium batteries are still too new to make such a bold claim on, and without saying what's in the "magic box" nobody is going to buy it.
Lead acid AGM can't last that long even in float service. NiFe & NiCad consumes too much water. Sealed NiMh does not have the cycle life, nor does NiCad.
So that leaves a magic battery. and while I'd love to have 72Kwh in a small zero maintenance 15 year box, I don't believe it's possible.
So when you come along and make a bold claim, you have to have some data (not "trust me") to back it up. Prove it works, not just promises.
Real engineering data is repeatable.
Continuing to sell snake oil will get you banned, Explaining what it is, is discussion. No More "Trust Me", believe me.

[SunEagle]

Nobody but a complete fool, is going to buy a "magic box" that claims to contain 72KWh in it and a 15 or 20 year warranty. Because the battery does not exist that can do that. Lithium batteries are still too new to make such a bold claim on, and without saying what's in the "magic box" nobody is going to buy it.
Lead acid AGM can't last that long even in float service. NiFe & NiCad consumes too much water. Sealed NiMh does not have the cycle life, nor does NiCad.
So that leaves a magic battery. and while I'd love to have 72Kwh in a small zero maintenance 15 year box, I don't believe it's possible.
So when you come along and make a bold claim, you have to have some data (not "trust me") to back it up. Prove it works, not just promises.
Real engineering data is repeatable.
Continuing to sell snake oil will get you banned, Explaining what it is, is discussion. No More "Trust Me", believe me.

Along with having a hard time believing in this "wonder battery" there is also the need to make sure it is tested and gets a UL listing otherwise most people will not be spending a lot of money on something that is not properly vetted as a safe product with a warranty that can be trusted.

If what the OP is talking about a possibility then I again hope him well. Although introducing a new product into a very active market would be similar to introducing a brand new automobile brand against the big players. That has been done before with not very good outcome to the new guy on the block. Even Musk is still having problems making a profit but time will tell.

[jflorey2]

I've taken few things from all this:
1) It is not feasible to provide battery banks to a market that is not there.
2) I'm not a sales person.
3) Do not go into full details.
4) That MPPT's minimize heat to the batteries!

Well, you are wrong on 1) and 4) - but 2) and 3) are personal choices you have to make yourself.

Looks like you're not going to be able to learn from this forum, so probably best if you try another venue.