Author Topic: Power Jack LF 5000W Inverter Board Swap  (Read 4429 times)

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Offline OTG

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #30 on: April 22, 2016, 08:47:35 PM »
Jeez fellas, way to hijack my thread... ;)

Seriously though, great to see more discussion, interest, and cool ideas (many of which go WAY above my head  ;D ). Not to mention I've hardly been punctual with this thread... but now I'm finally back for an update.

So I ended up cutting the black resin from the old Thermistor/Thermostat and used the new ones simply by sliding them back in (they're held tightly enough, and the fan still operates as it did previously). I then drilled new mounts in the chassis, and stuck the new boards in... but (there's always a but), the longer boards now created a clearance issue with the +/- MB wires to the +/- back panel terminals and the cooling fan. So after some strategic trimming of the fans shroud/frame, I managed to sqeeze it all back in, and in the end I just cable-tied the front panel voltage switch board through the grill/holes in the front panel (saved me buying a glue gun for this one job!).

And then, it worked! And has been working fine for 8 months now.

To note I did get an explanation (of sorts) from Cher on the mysterious eye terminal that comes out of the middle of the CB. Quote - "engineer said the cable is protecting the board when home AC power switch to inverter. " So seems it's Battery Charger/UPS function related?

Also I cant recall original readings (I recall others saying upto 8 Amps?) but with new boards idle current now sits at about 2.6A. Not great, but I think it has improved. The only thing thats still not fixed is the over sensitive, over voltage protection. But now living as the run-about inverter for job's around the block (bore/transfer pumps, circular saws, cement mixer, etc) it been well worth the investment.

However, there is one thing I love more than my LF5000... my LF8000!  :D

Idle current has definitely been sorted here... 0.6A! And it's soo quite compared to the hum of the LF5000, and easily handles everything I throw at it. Again the only issue is over voltage - that's next on my todo list for both units. I'll post another reply soon with a few questions for the local electrickery legends to help me nail that issue. Then I should be humming along very nicely indeed!  8)

Offline OTG

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #31 on: April 23, 2016, 12:11:07 AM »
OK folks - time to fix that pesky over voltage issue!

Now I've read the discussion on this issue by Lanyho and OZ (starting p.3 of the now biblical "guess who bought a power jack inverter" post), but I still have questions;

1. "How" does this fix work (I'm just a simple weekend electrickery warrior who wants at least a basic understanding of "what" I'm doing). My take is the “reverse breakdown” sends enough current the otherway that the CB OV function doesn't notice the higher voltages at the top end of your battery charge? How close was I?  ???

2. OZ said he used a 5v6 zener, but I've seen two different types (0.5W and 1W). Can somebody point me to the right zener (a link would be great!). Has anybody had success with other specs or even other devices?

3. My LF5k unit lives with both PWM and MPPT Charge Controllers. So per your advice OZ I'll be using a Zener. However my LF8k unit lives only with MPPT and in future I may want to use the Charge function with a generator. Sooo... is there a way (such as Lanyho's use of a 800k resistor) where I can fix the over voltage issue and still have the inverter effectively judge the SOC at the high end of a charge?

4. What's the best way to do it - de-solder the resistor, and solder back in with zener.  Or just 'tack' the zener onto the legs of the existing resistor?

5. Can of worms alert!!! I currently use Forklift Gel batts, my future plan is to use Nickel Iron (NiFe). Obviously @ 1.65V x 20 cells at full charge... could be 33V of trouble for a 24V LF and the over voltage fix. Anyway to factor this into the fix now, or should I just forget about that for now? PS: I recently found the below link re NiFe's and am thinking if I drop some cells, I too could get away with using lower voltage "Lead Acid" electronics?
      http://forum.solar-electric.com/discussion/17496/custom-inverter-charge-controller-settings-for-nickel-iron-batteries

6. I expect there shouldn't be any differences between doing this on the LF5k or LF8k?

Thanks all!  :)

Offline lighthunter

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #32 on: April 24, 2016, 08:49:25 PM »
Quote
Jeez fellas, way to hijack my thread.

I do apologize and will try to b more careful  :). I know ur joking but just the same.
respect goes a long ways. Thats one thing i like about this forum as opposed to some of the others, there are really a lot of great nice helpful people on here thanks to everyone who helps with that!

Trivia.  a 10w cfl bulb left on continuously uses 7.44kwh/mo :o. we have at least 2 that stay on 24/7 I never realized it. That could pump quite a bit of water from well etc.. Home power build has made me much more aware :)


I have no experience with the voltage mod as ive not had any problems with mine. I do however.
know how a zener would work in that application. The zener when inserted with the ring (cathode) end on the positive side of resistor and other end soldered to minus end of resistor of course will act as an open circuit (having no effect) until the voltage across the resistor reaches 5.6v called the breakover voltage. At that point current will start to flow more and more as voltage tries to go higher. This effectively clamps  the voltage across that resistor to 5.6vdc. I havent looked at how the rest of the circuit works so someone else may be able to help with that. If the overvolt circuit only monitors the + end of that resistor i would think it would disable the high volt shutoff feature. That b ok in most cases as other equipment can control max v on batteries.

Has anyone tried a couple capacitors across the resistor? I would think it would absorb the spikes allowing 30v accurate shutdown, that might be the function of the zener as it will bypass spikes and hopefully be open circuit to normal 29.8v condition. Then zener mod would be ideal solution.

Quote
future plan is to use Nickel Iron (NiFe).
   I used to drool about these batteries until i saw price...thats not even so bad considering the metal in them is resaleable to recover purchase price but then they last forever so. Ive not owned these so i cant comment. All i know is ive read specs and the charge voltage vs discharge voltage has quite a spread that inverters can struggle with also those numbers equate to serious efficiency loss. Imagine a battery with performance so good it acts like it has a built in voltage regulator.  I have 2 small LFP 12v batteries. (4) 3.2v cells in each. No larger than a couple lawn tractor batteries, yeah they costed $250 each but these things act like a perfect battery! If they are somewhere between 20% and 90% state of charge and the sun comes out, they will hold down a 50 amp charge rate with only a slight voltage increase, also seen em supply 40+ amps without more than 1/2v sag.  Thats more than 1C charge /disharge capable of 3C though im guessing something would suffer if you did. There is absolutely no heat at 1C (40A) maintained for stints of 5 minutes. They do it all at 95+%efficiency! Imagine a 400AH bank that you could use to 80%DOD. I just want you to know its an option.  :)
Good luck on that mod! ;)
LH.

LH

Offline OTG

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #33 on: April 28, 2016, 09:29:48 PM »
I know you're just being polite, but seriously lighthunter... don't ever be more careful!  The more posts on Power Jack the better for all of us!  :) And indeed! anotherpower is a godsend (especially for a hack like me! ;D ) and its members are great!

Thanks a bunch for the zener diode description lighthunter, that made perfect sense! And yes, I have a severe man crush on NiFe at the moment...  :P Thanks for mentioning LFP, they've never really factored for me, but they sound great. So I'll be taking a closer look at them when it comes to the big decision.

Quote
I have no experience with the voltage mod as ive not had any problems with mine.
- Really!? I thought this "feature" was common to all PJ's? What spec/how old is your inverter, does it have the std 10k resistor on "Cut if Low", and how do you charge your batteries? Do you think PJ's fixed it, or is something else in your system preventing the issue?

I did find a post detailing another attempt at solving this problem, here; http://www.anotherpower.com/board/index.php/topic,1108.0.html.

For now though, I just want the O/V issue fixed. I'll worry about generator charging and NiFi batteries later. So I've ordered some 1W (1N4734) and 1/2W (BZX55C5V6) 5V6 zener's and hopefully that'll do it for now. If anybody can confirm which they used (1 or 0.5W) that'd be great, otherwise if one fails I'll just try the other!  :D

Offline lighthunter

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #34 on: April 30, 2016, 05:42:27 PM »
Hi OTG,  i liked your comment to Grabra17 regarding his failed inverter. Very well rounded accurate info and encouraging besides.

Quote

" I thought this "feature" was common to all PJ's? What spec/how old is your inverter, does it have the std 10k resistor on "Cut if Low", and how do you charge your batteries?"

I will post pic of it. I bought it in 2014. It is 24v/110vLF6000 with one toroid. Another (actual spec 3k) toroid has been added to make it a 120/240 split phase true 6kw unit. To date, this one has had no problems yet.  I think its standard resistor ... blue color ring, i think is 10Meg resistor? Ive not measured it so i dunno. Battery charging "all" comes through the pj itself from grid tie. I'm guessing the toroids take most of the grid tie pulses out while the fet pwm pulses of pj are up there at a screech frequency to my ears, guessing 5khz or more. From what ive read on this forum its lower frequency higher current pulses that are a problem. Makes me wonder if anyone has tried an LC filter on their charge controller connection to batteries. With a large inductor in series and capacitor on battery side it would smooth those pulses.

 
Quote
"? Do you think PJ's fixed it, or is something."

My guess is its because ive never had an outback or midnit charge
control. The only one I ever used was a small windynation with 800w on 24v for 32A tops.
the rest of my panels were direct to bank through relay contact.

Dont get me wrong, Ive had this pj shut off from over voltage but its *always* been an actual over voltage condition and at 30v. Since im using LFP now 28 is my maximum and that.
Voltage control is done by means of an idec PLC with outputs tied to relays that add loads in increment to maintain correct battery volts. If it still cant control it, then it interrupts grid tie inverter. I dont use battery bank for storage, only for regulation as i use grid when RE isnt available, If I did buy a bank i dont know which type either. I wonder if forklift bat would give more per dollar? Just because used deals can b found. Performance wise LFP but NiFe has proof of durability and longevity.

Just a thought, do you have any way of recording what is happening with your battery volts? I use a cellog8S and it has been so much easier to program controls when i can review what happend during the day after making a change. Sometimes its surprising what you find.

Cheers!  :)LH
 



LH

Offline oztules

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #35 on: May 01, 2016, 02:00:35 AM »
"Makes me wonder if anyone has tried an LC filter on their charge controller connection to batteries. With a large inductor in series and capacitor on battery side it would smooth those pulses."

Yeah tried and failed with this setup too...2mh...... then I interfered with the resistor... and after that it ceased and desisted with telling me it's problems... the diode stops all that nonsense in it's tracks.

Must say I did not use the capacitor across the batts.


.................oztules
Flinders Island...... Australia

Offline lighthunter

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #36 on: May 04, 2016, 04:01:48 PM »
Thanks for sharing your experience with the choke Oztules! Saves us from the headache  :)Those ideas always seemed to work better on paper than they ever did in reality. what was that formula?1÷(2*pi* f *c)=XC that formula may give you an idea of the effective resistance of a capacitor xposed to a sine wave but then whats the frequency of a transient? dv/dt or the rise in volts/time? I never really understood all that even though i can do some of the math. I think the ESR value of a cap has more to do with shunting a transient than anything and the text books never mentioned that parameter when i... well im just too old, they probably do now.

I was trying to switch 150vDC with a contact yesterday and had a loosing battle with that one. Well loosing at least temporarily. I watched as my relay literally went up in flames. Nasty arc DC can sustain, i see why they use it in welding, can you imagine stick welding with solar panels? It would be smooth as glass. Anyway my second attempt at switching dc went better after i put a .1uf cap accross the points. Do you suppose the inductance of the long cable run is enough to cause the behavior? Mercy panel voltage is destructive. You cant really fuse to protect anything from adverse behavior either because ISC isnt much more than IMP.

The capacitor seemed to do the trick and i like the isolation but would i have better luck using a fet or igbt to switch than using a relay?

LH
LH

Offline lighthunter

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #37 on: October 02, 2016, 06:51:27 PM »
Hi all, there was a request to post pic of a toroid mentioned earlier in this thread so here it is alongside its equivalent spec pj torroid.

The pj torroid came out of a 24v 110v LF6000 without split phase.

Pj xfmr 4" height x 6.5" diameter 22lbs.
Powertronix 3"height, 8.5" diameter 31lbs.

These ran side by side for a year before i switched to an 8kw 200lb.
Split phase transformer. Will post it after the others.
LH

Offline OTG

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Re: Power Jack LF 5000W Inverter Board Swap
« Reply #38 on: March 11, 2017, 08:23:13 PM »
Finally closing this one out... hopefully it helps somebody. Though I see the new boards don't use Cut if Low, so I might have missed that boat!  :P

I tried both 0.5W & 1.0W Zeners  in parallel on my LF5000 and LF8000 inverters... and for whatever reason, they did nothing for either inverter. One lives on a PWM controller the other MPPT, both OV'd as per usual.

So I bought a bunch of resistors ranging from 650k to 1.2M and in the end I found:
- the LF8000 with a 1.2M in parallel
&
- the LF5000 with a 820k in parallel
had both of them working perfect!

The LF8000 worked with the 1.2M off the bat so I left it. The LF5000 would still OV to varying degress with larger resistors (e.g.  I had a 1.2M in it originally) but with the 820k it's had no troubles. I suspect the 8000 might be the opposite?

So after 6months of OV alarm free 'inverter-ing' I'm chuffed!  :)

Thanks again to all the good folks at AnotherPower for helping me get there!

Onto the next project... ;-D