Author Topic: Overvoltage shutdown issue  (Read 2563 times)

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Offline off the wall

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Re: Overvoltage shutdown issue
« Reply #15 on: December 26, 2015, 02:20:20 AM »
Thanks so much for posting about this issue - it's very helpful.

I use five 6mm2 wires to connect the inverter to the bus bar and wind each through 1 inch ferrites to calm down thin spikes. But perhaps one might employ a ferrite choke in the supply leads likewise to that which OZT discovered to be recommendable in series with the transformers.

Best wishes

OTW

Offline dochubert

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Re: Overvoltage shutdown issue
« Reply #16 on: January 19, 2016, 12:15:44 PM »
Hi,
Sorry for lack of posting lately.
Other projects and the holidays haven't left much time recently.
Thanks OTW for your reply and good wishes.  Very much appreciated.


I have been running the PJ inverter under various conditions, while trying to see those pwm spikes with my scopemeter.  So far no luck.  It being winter here, and lately cloudy and rainy, I might not be lucky enough to see them for some time yet.  I feel I need to see the spikes so I can tell when I've filtered them out.  Otherwise its ALL guesswork.

I think I may have the correct resistance to shift the high voltage trip to 64v (for 48v units) but will have to unsolder the pot to read the actual resistance value.  Haven't gotten around to that yet.  Eventually, I want to shift the trip point to 68v.  That would be 34v for 24v units and 17v for 12v, which I think should be the proper setpoint.  That change coupled with filtering of the control voltage to eliminate the pwm spikes to the voltage sensing circuit should get us reliable working inverters that still have reasonable high voltage protection.  That's the goal anyway.
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Offline dochubert

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Re: Overvoltage shutdown issue
« Reply #17 on: February 10, 2016, 03:58:19 PM »
Hi all,
Well, I've been running my pj inverter all I can and observing the voltage drop across that R14 resistor.  A few days ago I replaced the trim pot with a 7 megohm resistor;  7.2 megs being what the pot read when I removed it.  My readings indicate that this value should put the high voltage trip setpoint at approximately 64v (32v and 16v for 24 and 12v units).  A further guess would be about 5 megohms for r14 to put the setpoint at 68v.  I plan to run like this for a few more days taking readings before changing to 5 megs..

This of course doesn't address the issue of the pwm spikes.  (One problem at a time, and that will be next after I settle on a final value for R14.)  I'm still planning to put a choke filter inline with the power to the control board as my first attempt to solve this one.  Still open to ideas on what type/size/value filter to use.  It only has to handle 2 or 3 amps max that the control board uses but must be able to handle the 68v it might get to, say 70v max.  We don't want it to change the voltage or amps, other than suppressing those spikes/surges.
I have been trying to "see" the spikes on my scope meter.  I see some "noise" but it doesn't seem to be enough to be adding 2-4 volts to the battery voltage.  I am, however, seeing some AC voltage at inconsistent times; anywhere from .2v to 4 volts.  It usually doesn't last long, but maybe that's the results of the spikes, and the spurious shutdowns.
So far, with the 7 meg resistor at r14, no alarms or shutdowns.  It may be that getting the setpoint where it should be will give enough margin that the spikes won't shut it down either.  Probably wishfull thinking on that.

Anyway, now my posts are up to date with my progress, such as it is.  More to follow....
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Offline dochubert

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Re: Overvoltage shutdown issue
« Reply #18 on: May 21, 2016, 08:43:56 PM »
Well, as usually happens, other accomplishments have made this line of inquiry obsolete.
To conclude:
I am currently using a 5 megohm resistor for R14, and it seems to be what I wanted.  It puts the high battery voltage  trip point up to about 68 volts.  This is extrapolation from voltage drop readings across R14 as don't want to run my batteries that high just to test the setpoint.  On 24v units it would trip at 34v and 17v for 12v units.  (Piggybacking a second 10 meg resistor to the original 10 meg resistor gives an easy to do 5 meg R14)
The other part of the problem is the spike issue discussed previously will still cause a trip now and again.  Also, the temperature sensor for heatsink temperature that plugs in to the control board near the plug for the main fan affects the high voltage setpoint. It shouldn't, but it does.  As heatsink temp increases, so does the voltage drop across R14, pushing the unit closer to trip than it should be.
Since I had already added independent fan control, unplugging the stock heatsink temp sensor stops that problem.  So with the 5 meg resistor at R14 and the sensor unplugged, my pj runs without tripoffs so far.  The spikes can still get you, although much less often.
So, it can be done this way, but an occasional trip is still one trip too many in my book, so the zener diode is still the best solution overall.  As long as not having any high battery voltage trip is ok with the user.  Honestly, if your system is set up properly, a high voltage trip is unnecessary.

While arriving at this point, Oztules, Clockman and others have perfected a better control board, which I will be switching to as soon as I can.  So I guess that's it for this thread....
Thanks!
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Offline OTG

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Re: Overvoltage shutdown issue
« Reply #19 on: May 26, 2016, 05:01:43 AM »
Thanks for the final update dochubert... interesting to hear what sort of results can be achieved with resistors.

A little baggie of zeners finally arrived in the post the other day, so I'll be doing my knock-about LF5k unit tomorrow. Hopefully that'll make it OV alarm free for some remote jackhammerin' I've got to do. Then it'll be onto fixin' my frontline LF8k units...

I look forward to not having to flick the solar array off every time that dreaded beeping starts!  8)


Online oztules

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Re: Overvoltage shutdown issue
« Reply #20 on: May 26, 2016, 05:17:17 AM »
"I look forward to not having to flick the solar array off every time that dreaded beeping starts! "

You have persevered much much longer than me..... I was completely over it after the third time it went off....


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

Offline OTG

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Re: Overvoltage shutdown issue
« Reply #21 on: May 26, 2016, 06:33:26 AM »
Fridges, Laptops, the Wireless (a.k.a. radio), and lights all run straight off 24V DC. Don't watch TeeVee... even got a DC Mig welder... so the only time it's been a pain is when I'm "doin' a load" or running other AC appliances.

Plus I've had other tasks higher up my to-do list (mostly livestock related - jeez, I tell ya' owning a bull is great fun... :P ), otherwise, I assure you OZ it would have been sorted much, much, sooner!

But to your point, yes I was also over it after about the third time too...  :)

Offline dochubert

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Re: Overvoltage shutdown issue
« Reply #22 on: May 26, 2016, 01:06:07 PM »
You were right as usual Oztules, but guess I just had to beat my head against the wall a few (dozen) times before it soaked in.
Still, I learned a lot in the pursuit so no regrets
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Offline edgolla

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Re: Overvoltage shutdown issue
« Reply #23 on: February 06, 2017, 04:29:39 PM »
Do you know that you will get the wrong voltage if you try to measure the voltage across a 10 meg resistor with a normal digital voltmeter that has a 10 meg ohm input resistance.  Some of the cheaper ones from Harbor Freight and others have a 1meg input resistance.  With the 10 megaohm  ones you will get half the true voltage since you have cut the resistance in half.  Five megaohm instead of 10.

Offline dochubert

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Re: Overvoltage shutdown issue
« Reply #24 on: February 06, 2017, 05:30:32 PM »
In this case I believe it is the difference in the readings made with the 10, 7.5, and then the 5 meg resistors that tell the story, especially since the same voltmeter was used for all readings.  I used a harbor freight tools meter continuously hooked up to the resistor so I got a reading at a glance.  No doubt having the meter connected also affected the operation and readings slightly also.
Yes, there was some difference between my high quality meter and the hft meter, but the exact value wasn't so much the point as the change in voltage during various conditions.
For me, the discovery that the temperature monitoring circuit of the powerjack controller was affecting the overvoltage setpoint made using a zener to block that setpoint the only smart option, short of switching out the pj controller for Oz' much better controller.
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Offline welshman

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Re: Overvoltage shutdown issue
« Reply #25 on: February 06, 2017, 07:10:18 PM »
In this case I believe it is the difference in the readings made with the 10, 7.5, and then the 5 meg resistors that tell the story, especially since the same voltmeter was used for all readings.  I used a harbor freight tools meter continuously hooked up to the resistor so I got a reading at a glance.  No doubt having the meter connected also affected the operation and readings slightly also.
Yes, there was some difference between my high quality meter and the hft meter, but the exact value wasn't so much the point as the change in voltage during various conditions.
For me, the discovery that the temperature monitoring circuit of the powerjack controller was affecting the overvoltage setpoint made using a zener to block that setpoint the only smart option, short of switching out the pj controller for Oz' much better controller.

old thread but check out the latest PJ board, notice something missing. They must do things a little differently now?


Offline dochubert

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Re: Overvoltage shutdown issue
« Reply #26 on: February 06, 2017, 09:51:45 PM »
thanks for the info, Welshman
Interesting that powerjack has eliminated the r14 resistor.  I seem to remember that someone from powerjack said that the r14 really wasn't the place to adjust the overvoltage setpoint.  They referred me to two resistors on the underside of the control board.  I never followed up on them.  Possibly, with r14 eliminated on the newer control board, the value of one or both of the two others has changed.  Might give a better idea of how to properly adjust the setpoint.  Maybe putting a zener where r14 used to be would still eliminate the high voltage trip, otherwise those with the new boards aren't going to be able to stop the erroneous trips. 
Or maybe they set the setpoints to proper values and temperature no longer affects the high voltage trip?  (somehow I doubt it)
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Offline welshman

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Re: Overvoltage shutdown issue
« Reply #27 on: February 07, 2017, 11:54:18 AM »
thanks for the info, Welshman
Interesting that powerjack has eliminated the r14 resistor.  I seem to remember that someone from powerjack said that the r14 really wasn't the place to adjust the overvoltage setpoint.  They referred me to two resistors on the underside of the control board.  I never followed up on them.  Possibly, with r14 eliminated on the newer control board, the value of one or both of the two others has changed.  Might give a better idea of how to properly adjust the setpoint.  Maybe putting a zener where r14 used to be would still eliminate the high voltage trip, otherwise those with the new boards aren't going to be able to stop the erroneous trips. 
Or maybe they set the setpoints to proper values and temperature no longer affects the high voltage trip?  (somehow I doubt it)


Offline edgolla

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Re: Overvoltage shutdown issue
« Reply #28 on: February 07, 2017, 03:50:30 PM »
If the 10 meg resistor R14 is present, do you think a couple of microfarad non electrolytic  capacitor in parallel with it would help with any short term spikes.

Offline noneyabussiness

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Re: Overvoltage shutdown issue
« Reply #29 on: February 07, 2017, 05:08:15 PM »
Again i know its an old thread,  but just my 2 cents...

If you put a silicone diode in series with your zener (cathode to cathode ) it will effectively mute the temperature drift of the zener, as the silicone has a negative  temp co-efficient and the zener has a positive  temp co-efficient.. just adjust for the .7 volt drop of the silicone diode (so 6v use a 5.3v zener).

Also the drift you talk earlier about voltages i would put down to temp, generally a fixed resistor has a lower temp co-efficient  (drift) over its working range than a trim pot (way they are made etc.).. and as all have metioned filtering would dramaticly help..