Hi. I am new to solar and I just purchased a DC Solar trailer at auction.
The setup consists of 2 SMA Sunny Island Inverters, a Midnite Classic 250, 2 Industrial size FLA batteries, and 10 solar panels all mounted on a trailer. I managed to get the batteries charged up by hooking up a generator to the SI. All seem ok except that I can't get the Midnite Classic (CC) to charge the batteries. All connections are good; I also tested and measured the voltage and current of the panels to the PV combiner box. The problem is that the CC clicks periodically and switches back and forth between mppt bulk and resting but produces 0 watts. The CC displays the correct voltage, but is not pulling any amps to charge the batteries. Do I have a broken CC or am I missing something?
Any suggestions of tips would be appreciated.
Does the Classic PV input voltage ever drop below that Voc voltage that it started with ?
If not, then the Classic is not pulling the input voltage DOWN and supplying current to the battery and then after 90 seconds of having no output power, it goes to resting and wakes up again to try it again.
IF that IS the case, sometimes this can be fixed by making sure the top control board is fully connected to the bottom power board. I would try pushing the edges of the control board down to make sure all of the connectors are fully inserted into the sockets.... Please do this with the input NOT connected and battery breaker turned off just in case there is high voltage. Let it bleed down for a few minutes first, too if it was charged up.
Hi, Vic, Thai etc...
I see that this topic is "locked" and I do not know how that happened or how to unlock it right at the moment.
Maybe another moderator locked it ? I do not think these particular Classic 250s have a "warranty" but they should be able to be talked about IMO.
I will ask.
boB
I have unlocked the post. We are happy to discuss support issues with these Classics. As boB said, they are not covered under factory warranty but they are our product and we do support them.
boB, Sunshine,
Thank you both for helping and allowing the post to continue. This speaks volume for the group and for the company. My plan is to try all suggestions before replacing the charge controller with a "legitimate" unit so that it will be supported.
Again, many thanks,
Thai
Hi Thai, boB & Sunshine,
Thanks for Unlocking this Thread.
Welcome to the Forum Thai.
After trying to re-seat the control board, why not try seeing the RFR, as described here:
http://www.midniteftp.com/support/kb/faq.php?id=72
Wonder is there might be a high resistance connection in the wiring from the PVs, such that when the Classic tries to draw PV current, the input voltage falls, or similar.
Just a drive-by Post. Good Luck, Vic
You will need to look at the PV input voltage and I would suggest going to the MODE menu and selecting "Legacy P&O"
By setting it to P&O, (Perturb and Observe), this will cause the Classic to try and sweep a but slower than SOLAR mode
so that you can watch the PV input change. It will change only for a few seconds, maybe 30, but maybe longer.
If the PV input voltage does NOT come down, then the Classic has an issue. BUT we can try to troubleshoot here !
Do you own a soldering iron and some solder ? Any experience with soldering ? I'm just asking ahead of time, just in case.
boB
Hi boB,
I will place the classic in Legacy P&O mode in the morning as you suggest and watch for the change with the PV input. What should I expect? A dramatic drop or just a small change (10%? 50%?). I do have a soldering iron and solder. Can't say that I am the best at it, but passable. Willing to give it my best shot.
Many thanks,
Thai
Thai, first thing to look at is to see if the PV input voltage changes at all. If it moves one tenth of a volt though, that is not enough.
I have a suspicion that it will not move at all which MAY mean that there is a break in the connection from top control board to bottom power board.
At least the input is not shorted. That means that the smoke is still in the components ! :)
If it did change the input, it would move several 10s of volts like, from 170V to 100 volts or even lower. That would mean that is working though and from what you are saying and the pictures, although not a video, it sounds like it is not changing the PV input voltage.
Thanks
Hi boB,
Here is the result from the test:
The fluctuation is at the decimal level.
First round of test shows within this range 177.9V - 178.2V
Second round is within 177.3V - 177.7V
I am also including a link to a video during the Third test for your review:
https://www.dropbox.com/s/i4v0fmhz2s5dcqd/63304388570__C43F1F0F-02E4-49C9-9D62-A05A44A68D52.MOV?dl=0
Many thanks for your help and looking forward to the next step (soldering iron located and readied :-)
Thai
Thanks, Thai
Looks kind of what I thought it was looking like.
Do you have a meter ? In this case, a meter that measures resistance ? Ohms ?
Hi boB,
I do have a multimeter that can measure resistance.
Thai
Regarding the comment about a potential high resistance connection in the PV. Some of the trailers have had issues with the panel wiring or corrosion in the junction box on back of the panels (upside down storage position collecting water). So check the wiring carefully and look in the box on back of each panel, it will be obvious if that's a problem.
If nothing obvious, the panels or the string could be checked for short circuit current? Cover the panels, plug the leads together. Uncover again and check the current in the PV wire with a clamp on DC current meter. If there's some sun, it should show a couple amps.
Thai's problem has nothing to do with bad PV connections. A bad PV connection will not cause the input voltage NOT to drop when the controller sweeps.
I will put a picture of the PCB of the resistor to measure, Thai. Give me just a few minutes.
Thai, Measure R145 circled in blue in this attached picture.
It should measure to be around 10 to 20 Ohms. If it measures real high or say, higher than 30 Ohms, it is the problem.
Should be easy to fix that but let's see what it measures as. Make sure the power is off before measuring otherwise you may not get a good meter reading.
Hi boB,
It started to rain today (for the next few days) so I was not yet able to check out the board. But based on the image you sent for the R145, how do I measure? Where do I place the leads? Sorry for such a basic question, but I haven't done this on a circuit board before.
Thanks,
Thai
Quote from: Thai on January 26, 2021, 08:04:38 PM
Hi boB,
It started to rain today (for the next few days) so I was not yet able to check out the board. But based on the image you sent for the R145, how do I measure? Where do I place the leads? Sorry for such a basic question, but I haven't done this on a circuit board before.
Thanks,
Thai
Put your meter in ohms mode - if it has ranges and not auto ranging meter put it on lower ohms scale. Touch your leads together first to make sure your meter is working and you are on ohms - you should see some number close to zero. Then just measure the resistor with a meter lead on each side of the resistor .
Larry
Quote from: Thai on January 26, 2021, 08:04:38 PM
Hi boB,
It started to rain today (for the next few days) so I was not yet able to check out the board. But based on the image you sent for the R145, how do I measure? Where do I place the leads? Sorry for such a basic question, but I haven't done this on a circuit board before.
Thanks,
Thai
AND, in addition to Larry' guidance, the silvery ends of that resistor are its connection points. Place either lead of the DMM one one end of the resistor, and, the other lead on the other end (there should be very little difference in the resistance readings if the leads are reversed), and wait for the reading to stabilize. Those two thru-holes, one at each end of the resistor may well be its connection to the PCB. But, if possible place the DMM probe tips on the silvery ends of the resistor.
IMO, Vic
Quote from: boB on January 25, 2021, 07:19:30 PM
Thai's problem has nothing to do with bad PV connections. A bad PV connection will not cause the input voltage NOT to drop when the controller sweeps.
I will put a picture of the PCB of the resistor to measure, Thai. Give me just a few minutes.
YES, Thanks boB, would normally say, "what was I thinkin', but obviously, NO thinking was involved in that Post, sorry for any distraction in that poorly-reasoned statement.
Vic
Quote from: Vic on January 27, 2021, 10:15:35 PM
Quote from: boB on January 25, 2021, 07:19:30 PM
Thai's problem has nothing to do with bad PV connections. A bad PV connection will not cause the input voltage NOT to drop when the controller sweeps.
I will put a picture of the PCB of the resistor to measure, Thai. Give me just a few minutes.
YES, Thanks boB, would normally say, "what was I thinkin', but obviously, NO thinking was involved in that Post, sorry for any distraction in that poorly-reasoned statement.
Vic
That's OK, Vic. Happens to me ALL the time !
😁😁😁😀😀😎😅😑
Hi boB,
Thank you very much for your time and your help, but I am obviously over my head. It has been raining here (my SCC is mounted inside a cabinet outside on a trailer) and in a hurry, I attempted to measure the resistance and carelessly did NOT check to be sure that the SCC was shut off first. Consequently I fried it :-( and now it won't even turn on. My bad.
Anyway, many thanks for all your guidance and patience. I will contact tech support on Monday to see if I can ship it back for repair. Otherwise, live and learn ...
Have a great weekend!
Thai
OK, Thai.
That's OK. You tried. But as we always say, we do not make progress on electronics unless we have let the smoke out a few times.
So, you done good ! It's only a charge controller after all... And it's raining anyway so no power lost today.