Author Topic: Smoothing out the pulses  (Read 254 times)

Randaltb

  • Newby
  • *
  • Posts: 7
Smoothing out the pulses
« on: May 18, 2017, 11:33:07 AM »
Greetings:
I have my small home business/shop and home totally off grid. (Totally DIY)

I run :
- 4 x Classic 150's
- 9.3K Watts of actual panel. 
- 3 x Inverters (~10K of Pure sine)
    1 x Low Freq 6K
    2 x Switching style. 4K
- 7 x 24 volt x 100ah AGM Battery pairs.

The only real issue so far is that during peak loads 5.5K watts or more  (Three mini split AC units, lighting, small water heater, fridge etc) my led lighting starts to flicker/pulse.
It does it across all inverter, so it is not them...(Assumption)

It appears to be when my midnite 150s exceed ~ 2000 watts of output.
I "assume" it is the charge pulses getting to my inverters.

My question is how should I address this issue.
- 1st though is a capacitor bank/pack on the DC side, but do not know how the midnite will behave with capacitors in the mix.

What have you guys/Gals done to mitigate this?

Cheers

 
   

ClassicCrazy

  • Hero Member
  • *****
  • Posts: 1269
Re: Smoothing out the pulses
« Reply #1 on: May 18, 2017, 12:23:59 PM »
Are all your LED lights the same kind ?  There are a lot of variations on LED lights power supplies .  Are they dimmable or non-dimmable bulbs and are they on dimmable circuits?

What kind of inverters do you have ?

I searched for LED flickering on solar systems and there are many discussions about it with all kinds of explanations and possible solutions - here are a couple
http://forums.whirlpool.net.au/archive/2081139
https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panel-installation/21158-flicker-problem-everyone-stumped

Also if you search LED flicker you will see lots of info on that - here is one
https://knightsoundandlighting.com/2013/08/30/why-are-my-new-led-lights-flickering-on-the-dimming-system/

Search this " led lights flicker on  off grid solar system "  lots of discussions

After reading around some it wouldn't hurt to double check your wiring connections and think about how it is all hooked up. If it happens when Midnite controllers are maxing out that would be when all the connections need be the very best. Do you have an infrared temperature tester that you can check all your connections to see if any are heating up under load ?

Larry






 
system one
Classic 150 , 20 Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Westbranch

  • Hero Member
  • *****
  • Posts: 2450
  • Building System (sort of) 1 weekend at a time
Re: Smoothing out the pulses
« Reply #2 on: May 18, 2017, 02:37:47 PM »
I am suspecting it's when the CC is in its PWM mode. 
Which phase do you see this happen in?? Bulk, Absorb or float or one of the , I call them the   -----? MPPT modes.

Do you have 7 parallel strings of batteries in one bank?
Assuming that is right then you have 3  4 CC's feeding one Bat. bank.
« Last Edit: May 20, 2017, 12:42:31 PM by Westbranch »
CL647 asleep
KID 51(B) FW1811 560W C&D 24V 900Ah AGM
CL 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 x Cisco WRT54GLi/c DD-WRT Rtr &Brg, NetGr DS104Hub, 
Hughes 1100 Modem
Cotek ST1500 Inv OmniCharge 3024  Eu1/2/3000i Gens
West Chilcotin BC 1680W to come

tecnodave

  • Hero Member
  • *****
  • Posts: 575
  • Learn something new every day
Re: Smoothing out the pulses
« Reply #3 on: May 19, 2017, 05:33:19 PM »
Randalb,

What you didn't share with us is what are you running the LED lights on.....the inverter or battery direct.  I have 10 watt GE "Bright sticks" running on several different inverters and Chinese COB LED boards running on the DC side......the DC ones never flicker but I have had problems with flickering on high frequency inverters (Cotek) but don't have that issue with my large transformer high/low frequency inverters (Magna-Sine and Dynamote Brutus) . Some ( the home cheepo depot Chinese) ones do have considerable flicker....annoying

I think that the flickering has to do with the high frequency switching power supplies in some AC LED lights has to do with non sufficient load on the high frequency switching mode inverters and does not occur on inverters that have a large 60 hz transformer on the output. Such as the Outbacks and Magna-Sine and others that are high/low frequency design.

I also run 14 watt disk LED fixtures from Phillips and GE bright sticks on a Exeltech high frequency inverter with no flicker ever high load on minimum load.

David
#1 Classic 150 12 x Sharp NE-170, 2S6P, 24volt L-16 Rolls-Surette S-530, MS4024 & Cotek ,  C-40 dirv.cont. for hot water
#2 Classic 150 12 x Sharp NE-170, 2S6P, 24 volt L-16 Interstate,Brutus Inv.
#3 Kid/WBjr 2 Suntech 280 24v AGM 105 a.h. Exeltech Inv.
#4 Kid/WBjr 2 Suntech 280 12v AGM 105 a.h.

Randaltb

  • Newby
  • *
  • Posts: 7
Re: Smoothing out the pulses
« Reply #4 on: May 20, 2017, 12:28:42 PM »
Thanks for the replies.
I will try to hit all the questions

FYI: it is not limited to the LED lights, (I just "See it " there 1st)
** I also notice the (pulse) in other items, they are just more tolerant.


1. Yes the LED lights are all the same brand and model. (On the 120 side not DC)

2. I think the are dimmable but need to check)

3. Main Inverters:

 - Aims Power 24 VDC 6000 watt split Low frequency. (Huge heavy beast)
   Model # picoglf60w24v240vs

  - Aims 24 VDC 3000 Watt Pure Sine.
    Model # pwrig300024120s
 

4. 4 x midnight classics on one Battery bank.

5. Yes I think it is during Bulk Charge.

 

Randaltb

  • Newby
  • *
  • Posts: 7
Re: Smoothing out the pulses
« Reply #5 on: May 20, 2017, 12:49:53 PM »
Also Just to toss it out before I get asked:

The wiring Battery Bank <--> Inverter is only ~4 ft.(Max) and I have rechecked the crimps etc. and they are clean and tight.
** They don't get hot either, if they did I would scale up.
     Also at full Inverter draw they barley warm up.
 

I am pretty sure it is caused by the CC PWM Pules during Bulk Charge mode.
** But only at high draw(2K up each classic)

And if I kill the DC side breakers from the PV's it stops.

Basically I am considering a capacitor bank (size TBD) in parallel with my batteries.
Just not sure if the Classics will have any issue with it?
** I assume not, but always good to ask...



 



Vic

  • Hero Member
  • *****
  • Posts: 1674
Re: Smoothing out the pulses
« Reply #6 on: May 20, 2017, 01:47:03 PM »
Hi Randlaltb,

So,  guess that you are running SEVEN parallel strings of 12 V AGM batteries (?).

Parallel strings can be very problematic  --  the greater the number of parallel batteries,  the worse the situation can be,   due to often poor current sharing during charge and discharge.

Would suggest that you carefully disconnect all battery interconnects,  clean each mating surface,   and coat with petroleum jelly,   and tighten well,   each connection.

A 6000 W inverter on a 24 V system,   is quite large.   And,   AIMS has worked very hard to earn a non-stellar reputation for their inverters.

AGM batteries generally like very long Absorb cycles  ...  how are you terminating Absorb?   It can be a bit difficult to have the desired long Absorb on off-grid systems.

What brand are your batteries?
Are the batteries all the same age?
What are the Absorb voltage and Float voltage settings on the Classics?

How is it that you have decided just where to place the BTS/es,  with SO many batteries  --  if you have multiple BTSes in the system,   are all of them on a single battery?

Are you using Follow Me on the Classics?

What is the cable size that connects the batteries to the inverters?
What cable size is used for the interconnects between the batteries?
What size are your solar arrays?   Does each Classic have its own PV array?

Just my opinion,   but I have not ever seen any flicker on fluorescent or LED lights caused by any Classic.

Enough for now.   Thanks for the answers!   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

tecnodave

  • Hero Member
  • *****
  • Posts: 575
  • Learn something new every day
Re: Smoothing out the pulses
« Reply #7 on: May 22, 2017, 12:18:37 PM »
Randaltb,

First off the Classic is not a PWM controller.......its MPPT......its a "buck converter"! It is in MPPT mode whenever the batteries are at a voltage lower than the set point for that charge stage. Does not matter which stage....be it Bulk....Aboorb...Float...or Equalize......as long as the battery bank can accept the full output of the input source thr Calssic will be operating in MPPT mode.......now then when the voltage reaches the set point for that stage and there is more solar input than needed to maintain that voltage the controller drops out of MPPT mode but it's still a buck converter.....not a PWM controller.


I am not even going to comment on using 7 battery strings in parallel........they cannot be balanced......period......not ever!  This practice has led to many system failures and will continue to do so far into the future!


What is causing the flicker is unstable system voltages.......look into your wiring for high resistance connections......poor voltage following.

Not a fan of AIMS inverters, my thinking is inverters that have huge transformers........huge inductive cores and huge capacitors.......make for system stability.

My way antique Dynamote Brutus inverters have a cleaner sine wave than anything else that I have seen.......absolutely no noise on my way high end hi-fi gear.......Carvers and Haflers.......the Brutus inverters have larger transformers than anything in their class......also way more overload capacity of any inverter in class........3200 watt Brutus will start 11,900 watt load!.....My 4000 watt Magna-sine won't do that!..not even half that!.......nor any other 4 kW class inverter that I'm aware of. That is the result of huge electromagnetic storage capacity.

My first suggestion is that you run the Classic output directly to the battery bank......with the output breaker being the only thing between the classic and the battery. No shared busses , no shared wiring with anything else.

All of my controllers are wired with separate runs to the battery bank......no shared wiring....I have a very clean system.

I use individual battery banks that are basically huge.....2 main banks ( not paralled) at 480-500 a.h. Plus my new approx 4500 a.h. Bank. (1050 amps at 8 hour rate)   (Salvaged 36 volt forklift battery) with bad cells removed now 24 volt.

Keys to system stability:  huge battery bank.....direct wiring with minimum wiring loss.....big inverter with lots of inductive/capacitive energy storage.

Hope that this info will help you get a clean stable system.

David

#1 Classic 150 12 x Sharp NE-170, 2S6P, 24volt L-16 Rolls-Surette S-530, MS4024 & Cotek ,  C-40 dirv.cont. for hot water
#2 Classic 150 12 x Sharp NE-170, 2S6P, 24 volt L-16 Interstate,Brutus Inv.
#3 Kid/WBjr 2 Suntech 280 24v AGM 105 a.h. Exeltech Inv.
#4 Kid/WBjr 2 Suntech 280 12v AGM 105 a.h.

dgd

  • Hero Member
  • *****
  • Posts: 1673
    • Lorylink
Re: Smoothing out the pulses
« Reply #8 on: May 22, 2017, 11:55:08 PM »
Keys to system stability:  huge battery bank.....direct wiring with minimum wiring loss.....big inverter with lots of inductive/capacitive energy storage.

now that has to be the best advice I have ever seen on this forum except I'd have written HUGE and BIG

dgd
Classic 250, 150,  20 140w, 6 250w PVs, 2Kw turbine, MN ac Clipper, Epanel/MNdc, Trace SW3024E (1997), Century 1050Ah 24V FLA (1999). Arduino power monitoring and web server.  Off grid since 4/2000
West Auckland, New Zealand

boB

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 2578
Re: Smoothing out the pulses
« Reply #9 on: May 23, 2017, 01:12:06 AM »

Hi...  A few questions...

What is the approximate repetition rate of the flickering ?  Is it evenly timed or does it seem to be random ?

What is the approximate battery voltage when the flickering happens ?

Do you notice the current limit LEDs lighting up or the Current Limit message showing up on the LCD display ?

One thing that was mentioned was to wire the Classic's battery cable more directly to the battery terminals.  What can happen
when CC's and inverters are wired closely together and separated from the batteries (electrically), the inverters may
be sourcing a lot more from the chargers than the batteries themselves.  This is usually more of a CC problem than
an inverter issue but wiring the CC's closer to the batteries can help filter that 24V DC much better.  Remember that
these low frequency inverters will draw a huge amount of 120 Hz ripple current from the batteries and the inductance
of the battery cables can also separate the inverters more from the batteries electrically.  Even larger battery cable
will not fix that. Only shorter battery cables.  At least you are not running at 12V DC !

Thanks,
boB
K7IQ

Randaltb

  • Newby
  • *
  • Posts: 7
Re: Smoothing out the pulses
« Reply #10 on: May 23, 2017, 03:30:53 AM »
Thanks for all the replies
I will try to address most of the comments:

Batteries:
All 100AH 12 volt AGM, same vendor, all same age.
    - 2 x batteries in series = 24 volts.
    - 14 batteries total = 7 pairs
** All voltage are very close (if not the same) even under load.

The 4 CC(s) are using Follow me.
No faults no over current or temp etc.

The Bulk Charge runs them up to 28.6 volts. (14.3 per bat...)
It holds that for two hours, then the CC then drops to 28.2 till sun set.

BTW: I am in AZ I have plenty of sun to fully charge the bank everyday.
         
I noted a comment on high resistance connections.
The battery cables are welding cable with very low resistance. (I did not cheap out on wire)
The center link between battery pairs is also two cables. (To reduce  chance of balance issue)

Connection are spotless and tight with all stainless fasteners.  (I even dust the things :)
Also not sure why anyone is assuming I think my MPPT Charge controller is PWM?
The only "Pulse" I am referring to is on the battery charging side.
** I "assume" the battery charging is pulsed, and that is why when I shutdown the CC's the issue goes away...

Bob:
- Rate of the flickering, I am not sure but it is stable. (Like it is being generated)
- What is the approximate battery voltage when the flickering happens ? 28.2 (I need to verify this it could be lower and I did not take notice)
- No error on the CC

Tecnodave:
The big transformer comment, I totally agree with, did you look at that model # on my 6K unit, it is all transformer. (It weighs a ton!)
And it will start a 5HP compressor while running the lights and stereo never missing a beat.

Also you mentioned:
"run the Classic output directly to the battery bank......with the output breaker being the only thing between the classic and the battery. No shared busses , no shared wiring with anything else."
** It is, and no CC is connected to the same battery either. (Evenly spaced across the bank)

Summary:
The issue seldom occurs, and the system runs smooth as glass 99% but on several days I have seen this flicker. (It is not just the lights)
By the time I get a meter and start trouble shooting the load changes and it stops.

My "assumption", is it the charging "Pluses" from the CC briefly spike up in voltage in response to the load causing voltage pulses.
The issue happens when the CC(s) are all pushing 70+ amps out and the battery load is just enough the batteries are not smoothing it out.

I think the batteries are staying at voltage but need to verify.

BOB, made a good point, about the 120hz ripple that might be being created by the Low Freq Inverter. (It is the biggest beast in the system...)

My question is can I add a capacitor/bank to smooth this out, just like the output (Filter) side of a DC power supply.
I am betting yes, but really big caps...

My main take away from this is:

- Shorter wires
- Possible ripple feedback from the Low Freq Inverter.

I will test this out and get back to you all.

Thanks again
Randal











 

Randaltb

  • Newby
  • *
  • Posts: 7
Re: Smoothing out the pulses
« Reply #11 on: May 24, 2017, 03:16:12 PM »
OK minor update.
I ran that batteries a bit lower than normal two nights in a row.
This caused the charging to exceed 7K watts.

The Idea was to force the system into a flicker/ripple based on the charging with a light Inverter load.
The system ran smooth as glass both days, no noise/flicker etc.

So!
That leads me to lean away from the classic's being the source.
I am not convinced, but I am leaning towards this being related to the peak inverter drawn ripple.

I will update you as I narrow this down.

Thanks again

 

Randaltb

  • Newby
  • *
  • Posts: 7
Re: Smoothing out the pulses
« Reply #12 on: May 31, 2017, 12:09:48 PM »
OK, we may have solved the issue (TBD)
One of my classics quit out putting power.

My current "assumption" is that I was seeing the effect of a failing output.
I will update the thread once that CC goes back online.