MPPT input voltage comparison

[native pepper]

Gotta disagree, been using my 3 PWM chargers on my 800 Ah bank for a few years now, no problems. Fill the bank up and then stop, so what is the issue ? Using basically good quality LA charger on my 200 Ah 12 pack as well, still no issues.
Too much male bovine excreta about this whole topic in my opinion.
I would like to see some scientific studies from LiFePo4 battery makers (or others) doing a comparison of PWM charging and MPPT charging on these cells, not just reference to "what my old mate felt was best" Possible ?

Cheers
William

Was talking in regard to the times when it was cloudy, or shaded, which is when mppt comes into it's own and not over all, assumed those with some intelligence would recognised that reality. It was my old mate, who was at the forefront of developing charging and control systems for lifepo4, before he died. He designed and made the first real cell equalisers, single stage bulk chargers and heavily tested all standard lithium chemistries, to attain the best outcome with them.

Let me know when your lifepo4 pack reaches 10-12 years and still has 100% capacity, using your charging system, like mine has, using my old mates system. Seems to me the supposed experts and certainly manufacturers are still living in the last century, clinging desperately to profit growth last century technologies, which is what I've seen with others who have lifepo4.

Their systems using lead acid charger and controllers, like you are and just getting to 3-5 years of use, already have lost some capacity. Did my own tests with pwm and mppt, under the same cloudy and shaded conditions, mppt, provided the most input over the day by a long shot. When you are on the road a lot, getting that extra input whilst in shade or cloudy conditions, can make a big difference to your life style and the same at home. Especially as lifpeo4 love bulk charge, but hate slow small charges, making lead acid controllers etc, detrimental to lifepo4 long life. Read the real science for them, not profit growth industries desperate to keep their market share with increasingly obsolete crap and are renowned for misleading customers.

So apologise for offering up a system approach, which has been proven to work over a 12 year period, certainly no where near as good as the one you are using currently and seems to be working for you so wonderfully. How long did you say you'd be using and testing lifepo4 for?

[Busman]

5 or 6 years
I do note however that there are no references from battery manufacturers, no scientific studies doing comparisons.
This is would what I would like to see, rather than a statement that Liths "hate so and so charging regime" That means nothing.
Again, is this possible ?

[El Gringo]

I asked the same question on another forum. All you ever get back is if you don't understand basic electronics you won't get how Mppt works so much better.
So, same as usual, ask too hard a question you get belittled instead.
I have seen numerous trials and tests done and the only common thing amongst them all is that PWM put more charge into the battery than MPPT.

In my opinion this MPPT thing is just a marketing ploy so you will pay double for the unit that only costs cents to make.
If this were not the case manufacturers would publish their own testing methods and results - none of them do.

Cheers,

[Busman]

Bernie,
I agree, there may be some situations where you can extract a little more but the claims made are lets say extravagant. The earlier post seems to intimate that all PWM chargers are trickle chargers ? Someone forgot to tell mine.
When our batteries need charging and the sun is shining we see 100 amps going into the Liths bank, when it gets very close to set point the ramp down is bloody steep, until bugger all if no draw, if there is a draw, then solar is allowed through to cover it.
I just cannot see any SCIENTIFIC evidence that either regime is infinitely better than the other, that's what I would like to see.
Does anyone have such evidence ?
William

[native pepper]

5 or 6 years
I do note however that there are no references from battery manufacturers, no scientific studies doing comparisons.
This is would what I would like to see, rather than a statement that Liths "hate so and so charging regime" That means nothing.
Again, is this possible ?

You have to understand I have no technical knowledge whatsoever, other than hands on, watching lots of tests and being able to wire up and put things together properly. It means a lot if you've done some reading on the subject and not just listened to supposed experts in the subject, who have last century electrical qualification. As well as not undertaken any real testing, which is really expensive or used them for a long time and my old mate used me as the field tester, for dummies.

You ask all these experts and none have a clue beyond their initial lead acid training, so they jump on the band wagon claiming because they are qualified, they should know and they don't have a clue. No long term experience, or testing, when they don't have an answer, they either start abusing, or go into a technical jargon filled rant, in the hope it will confuse people enough to shut them up.

Everything I've read from those who have done real bench and field testing, support the following, only bulk charge, never float or use any other lead acid parameters and never use trickle charge when they are getting close to capacity. Never charge your cells over 3.5v, or drop below 3v, use proper cell equalisation and never use bleed equalisation. Don't leave your cells in temps below 16-18deg when in use and never leave them in temps over 30deg, regularly. That's why my knowledgeless old mate developed a temp controlled pack box for use in off grid extreme climate areas and it works.

So far that has worked for me and still have my first li-ion battery in my old huewai phone, which is over 10 years old, same with my smart ph and have the other long term lithium aaa/aa cells have had since new. Never let any of them get above 80% charged, or below 25-30% and my smart phone, try to keep between 65-75% SOC. My knowledgeless old mate taught me that one also.

Have 40amp lifepo4 cells over 10 years old, which have been sitting at 3.2v for all that time including 3 cells that went through a fire test and have lost nothing in capacity. To me that's real testing in progress and more reliable than all the useless mumbo jumbo supposed experts spew out, yet to see anyone following the lead acid manufacturers recommended charge methods and parameters, that hasn't had problems and or losing capacity after 3-5 years.

If it's working for you, stick with it, that's how our society works, smoke and mirrors, to keep the profit growth industry going, the people conned and not give long term service. Keep getting told my approach to life, energy and travel is ridiculous and can't work. But have fuel bills of less than $50 a year and travel 10000-20000+ klms each year for that cost and no energy costs at all, or have a problem with by lifepo4 system.

[native pepper]

The earlier post seems to intimate that all PWM chargers are trickle chargers ? Someone forgot to tell mine.
William

If that was directed at my post, then you didn't read it. MPPT are designed for low light situation, they would provide no extra benefit in the desert where you get cloud cover just a couple of times a year, other than approaching dusk or dawn. But in shaded and cloudy areas, they provide more than a PWM and if you live off grid all the time, then over a year MPPT pay for themselves.

[Busman]

NP you tell us you have no technical expertise at all, yet then tell us that your system is the best thing since sliced bread ? And the only way to do things. I am sure that is not the case.

I ask again, where is the scientific evidence to back all this up ? I am only interested in knowledge, not opinions in how the world should, or does work.
Why is this not able to be obtained ?

William

[jon_d]

I honestly don't understand why people are so argumentative over this subject.


There are simply 2 schools of thought. They work differently; and even within the subject of EACH, PWM and MPPT, different manufactures designs and internal electronics and logic are different. And consequently, the holistic system designs are different too.

There will never be a away to do a comparison between the subjects of MPPT and PWM. Any comparison will be so general; it invites arguments because people will quote specific use models to argue a point.

One might be able to do comparisons between 2 controllers in an exact and controlled environment. And let's face it; none of us have the resources to perform that test..... AND even then, the results will be different based on the usage and solar parameters applied. All it would do is give a set of results for a set of conditions..... but "what about a different set of parameters???" and around we go again.

Even then once the results are published, there is no answer... because the user would need to determine which solution best suits their needs.



Getting shitty and arguing the piss out of each other is not going to change anything or anyone's opinions.

The only thing it does is leave a bad feeling in otherwise a great friendly place.

I suggest just enjoy your own system and choice. AND importantly, respect the other persons choice.
Because they are probably thinking the same about you as you about them.


end of rant - apologies - sheeeesh.

[dapope]

I honestly don't understand why people are so argumentative over this subject.


There are simply 2 schools of thought. They work differently; and even within the subject of EACH, PWM and MPPT, different manufactures designs and internal electronics and logic are different. And consequently, the holistic system designs are different too.

There will never be a away to do a comparison between the subjects of MPPT and PWM. Any comparison will be so general; it invites arguments because people will quote specific use models to argue a point.

One might be able to do comparisons between 2 controllers in an exact and controlled environment. And let's face it; none of us have the resources to perform that test..... AND even then, the results will be different based on the usage and solar parameters applied. All it would do is give a set of results for a set of conditions..... but "what about a different set of parameters???" and around we go again.

Even then once the results are published, there is no answer... because the user would need to determine which solution best suits their needs.



Getting shitty and arguing the pistol out of each other is not going to change anything or anyone's opinions.

The only thing it does is leave a bad feeling in otherwise a great friendly place.

I suggest just enjoy your own system and choice. AND importantly, respect the other persons choice.
Because they are probably thinking the same about you as you about them.


end of rant - apologies - sheeeesh.

Pretty much.

[T1 Terry]

I have no intension of throwing fuel on this fire but I'd be very interested in the recorded graphs that show cell voltage while the capacity tests were carried out along with the test parameters like battery advertised capacity and load applied in amps or watts, which ever you have.
Nasa only have long term data for lithium batteries with 10 yrs service so 12 yrs and still 100% capacity will shed a whole lot more information about how these batteries behave after long cycle use. I would imagine professor Jay Whitacre of ex Carnegie fame into lithium battery research and the founder of the lithium salt water battery will also be very interested in your findings

T1 Terry