Would you buy if offered Battery Bank?

[Sunking]

Is this thread still going on? I need a battery that will store 14,000 KWH at 100% efficiency for 8 months.
Sunking would be more fun if he would not hold back so much. Bruce Roe

So grumpy because I have been in Seattle for a week for Boeing 100th Birthday bash. What a Cesspool Seattle has turned into. Makes it real easy to see why suicide rate is so high there. I was there for a week and wanted to cut my throat. Feeling better now, got some sunshine, away from drug addicts and tent cities. Heck Seattle turned I5 into a Parking Lot.

[bcroe]

Is this thread still going on? I need a battery that will store 14,000 KWH at 100% efficiency for 8 months.
Sunking would be more fun if he would not hold back so much. Bruce Roe

[Sunking]

Told you he was a LIAR. Only one dumb enough to believe it is Dan.

[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.

[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.

[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.

[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!

[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.

[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]

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.

[einsvanian]

I say it minimizes on heat you say it doesn't. That is our own opinions.

We both can agree that the PWM and MPPT can charge batteries, right? We can both agree that the MPPT allows higher voltage from solar panels and lower voltage on battery banks, right? We can both agree when using PWM's solar panels have to closely match the battery bank voltage, right?

Who cares what it actually does: in theory, it does its purpose: it steps down voltage and charges batteries.

We are arguing over something so small that consumers don't really care, as long as their batteries are getting charged; it doesn't matter.

I look at it with electronic theories; you look at it with electrical theories. You and I can both agree that both devices are electronics, right?

Would you allow an electronics technician work on electrical; or an electrician work on electronics?

[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.

[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]

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]

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.